p.235

6_______________________

Meeting the requirements of the Building Regulations – Dwellings

6.0  Introduction

6.0.1  How to use this chapter

This chapter has been designed to help you meet the requirements of the Building Regulations in dwelling houses, flats and rooms for residential purposes (hereafter referred to as dwellings). We have adopted a foundations-up approach, as shown in Figures 6.0.1 and 6.0.2, by putting all the relevant Approved Document requirements that relate to each specific area (e.g. windows) into each section.

p.236

Authors’ note: In Chapter 7, we describe the requirements for ‘Buildings other than dwellings’ but, as a high percentage of the requirements, information and explanations about Building Regulations in dwellings is also applicable to buildings other than dwellings, Chapter 7 will only include information specific to non-dwellings.

However, to assist the reader, we use the same sub-chapter heading in both chapters (for example, 6.1 and 7.1 are both entitled ‘Foundations’). The reader using Chapter 7 will need to refer back to Chapter 6 to see if there are any general purpose requirements or information that should be taken account of.

Each section of Chapter 6 is structured to discuss the precise requirement and then how to meet the requirement. Sections start with a table which shows which part of each Approved Document applies to a particular aspect of the building. For example, in the case of foundations, this would be:

p.237

p.238

6.1  Foundations

6.1.1  Requirements

p.239

Very often, a number of Approved Documents will apply; therefore, each section follows the alphanumeric order of the Approved Document. Where a specific Approved Document does not apply, it is omitted from the section.

In the case of the example above this would be:

p.240

6.1.2  Meeting the requirement

6.1.2.1  Structure

6.1.2.1.1  Structural safety

and so on

Note: Cross-sectional diagrams, tables and further amplification are also provided where necessary.

We follow the same numbering order in each section and also number figures and tables by section so that you can easily find what you are looking for.

p.241

For your assistance (and to avoid you having to constantly refer back), where tables and figures are common for a number of sections we have deliberately duplicated them in each section.

Chapters 6 and 7 are further supported by appendices, which cover specific areas in greater detail (as entities in their own right rather than how they apply to a particular project) and these are available on the publisher’s website at www.routledge.com/9781138285163.

p.242

Owing to the huge amount of information contained in the Approved Document series, and in an effort to help you ‘sort the wood from the trees’, the following symbols have been used to help you.

p.244

6.0.2  Background

The Building Regulations provide a practical guide to meeting the requirements of Schedule 1 and Regulation 7 of the Building Regulations and the latest edition of the Building Regulations and the Building (Approved Inspectors etc.) Regulations.

Since the issue of the Building Regulations 2010, two new Approved Documents have been added (namely Q and R) and Approved Document M has been substantially revised. Approved Document N was removed and its contents added to Approved Document K and M. There have been consequential revisions to other Approved Documents as a result of these changes.

6.0.3  Approved Documents

The documents listed in Table 6.0.1 are derived for the latest amendments of the Approved Documents at time of writing.

p.245

Note: The changes to Approved Documents apply initially in England until the devolved governments adopt them for their own publications.

Electronic copies of Approved Documents may be downloaded from the following sources:

Bound copies may be obtained from TSO (see www.tso.co.uk) or RIBA (www.architecture.com).

6.0.4  Compliance

There is no binding obligation to adopt any particular solution that is contained in an Approved Document. However, as the Approved Documents contain both the guidance on how to comply with the Regulation as well as extracts from the Regulations, you should be careful to ensure that you comply with the regulatory text! However, should a contravention of a requirement be alleged, if you have followed the guidance in the relevant Approved Documents, that will be regarded as evidence suggesting that you have complied with the Regulations. If you have not followed the guidance, that will be viewed as evidence suggesting that you have not complied with the requirements, and it will then be up to you, as the builder, architect and/or client, to demonstrate how you have satisfied the requirements of the Building Regulations.

p.247

6.0.4.1  Building Control Body compliance

Fixed building services, including controls, should be commissioned by testing and adjusting as necessary to ensure that they use no more fuel and power than is reasonable in the circumstances.

If you are intending to carry out building work, it is best to always check with your Building Control Body (BCB) or one of your Local Authorities’ Approved Inspectors first to ensure that your or their proposals comply with Building Regulations!

6.0.5  Responsibility for compliance with Approved Documents

It is important to remember that, if you are the person (e.g. designer, builder, installer) carrying out building work to which any requirement of Building Regulations applies, you are directly responsible for ensuring that the work complies with any such requirement.

The building owner also has a responsibility for ensuring compliance with Building Regulation requirements, and could be served with an enforcement notice in cases of non-compliance!

p.248

6.0.6  Materials and workmanship

Any building work which is subject to the requirements imposed by Schedule 1 to the Building Regulations shall be carried out in accordance with Regulation 7.

Building Regulations are made for specific purposes (primarily the health and safety, welfare and convenience of people and for energy conservation) and these are supported by guidance standards and other technical specifications relevant to these Regulations. The supporting documents may also address other aspects of performance or matters which, although they relate to health and safety, are not directly covered by the Building Regulations. In accordance with Regulation 8 of the Building Regulations, the requirements in Approved Documents (except for G2, H2 and J7) do not require anything specific to be done except those things which are needed to secure reasonable standards of health and safety for persons in or about buildings (and any others who may be affected by buildings or matters connected with buildings).

6.0.7  What materials can I use?

Other than for short-lived and unusable materials (see below), you may show that you have complied with Regulation 7 in a number of ways, such as by using:

p.250

Note: Where there is no relevant harmonized European standard, then tests, calculations or other means may be used to demonstrate that the material can perform the function for which it is intended.

Authors’ note: Following Brexit there is likely to be much change in this area as the British Standards decouple from the European regulations. At the time of writing there was no guidance on the likely scale of such changes.

p.251

6.0.8  Short-lived materials

Even if a plan for building work complies with the Building Regulations, if this work has been completed using short-lived materials (i.e. materials which, in the absence of special care, are liable to rapidly deteriorate in relation to the expected life of the building) the Local Authority can:

(Building Act 1984, Section 19)

p.252

6.0.9  Unsuitable materials

If, once building work has begun, it is discovered that it has been made using materials or components that have been identified by the Secretary of State (or a nominated deputy) as being ‘unsuitable materials’, the Local Authority has the power to:

p.253

(Building Act 1984, Section 20)

If the person completing the building work fails to remove the unsuitable material or component(s), then that person is liable to be prosecuted and, on summary conviction, faces a heavy fine.

p.254

6.0.10  Technical specifications

Building Regulations may be made for specific purposes such as:

p.255

Note: These are aimed at furthering the protection of the environment, facilitating sustainable development, or the prevention and detection of crime.

Although the main requirements for health and safety are now covered by the Building Regulations, there are still some requirements contained in the Workplace (Health, Safety and Welfare) Regulations 1992 that may need to be considered, as they could contain requirements which affect building design. For further information see Workplace (Health, Safety and Welfare) Regulations 1992. Approved Code of Practice L24 (Second Edition, 2013).

p.256

Standards and technical approvals, as well as providing guidance, also address other aspects of performance, such as serviceability and/or other characteristics related to health and safety not covered by the Building Regulations.

When an Approved Document makes reference to a named standard, the relevant version of the standard is the one listed at the end of that particular Approved Document. However, if this version of the standard has been revised or updated by the issuing standards body, the new version may be used as a source of guidance, provided that it continues to address the relevant requirements of the Building Regulations.

The Secretary of State has agreed (with the British Board of Agrément) on aspects of performance that they need to assess in preparing their Agrément Certificates so that the Board can demonstrate compliance of a product or system with the requirements of the Building Regulations. An Agrément Certificate issued by the Board under these arrangements will give assurance that the product or system to which the certificate relates (if properly used in accordance with the terms of the certificate) will meet the relevant requirements.

p.257

6.0.11  Independent certification schemes

Within the UK, there are many product certification schemes that certify compliance with the requirements of a recognized standard or document that is suitable for the purpose and material being used. Certification bodies that approve such schemes will normally be accredited by the United Kingdom Accreditation Service (UCAS).

Competent person self-certification schemes that register installers of materials may also be used as a means of ensuring that the work is carried out by a competent contractor and to the appropriate standard.

6.0.12  Standards and technical approvals

Standards and technical approvals provide guidance related to the Building Regulations and address other aspects of performance, such as serviceability, or aspects which, although they relate to health and safety, are not covered by the Regulations.

p.258

6.0.13  House – construction

There are two main types of building in common use today: those made of brick and those made of timber. There are many different styles of brick-built houses and, equally, there are various methods of construction.

Brickwork, as well as giving a building character, provides the main load-bearing element of a brick-built house. (See Figure 6.0.3).

Timber-framed houses, on the other hand, are usually built on a concrete foundation with a ‘strip’ or ‘raft’ construction to spread the weight, and differ from their brick-built counterparts in that the main structural elements are timber frames. (See Figure 6.0.4.)

p.259

6.0.14  Buildings – size

6.0.14 1  Classification of purpose groups

Many of the provisions in the Approved Documents are related to the use of the building. The classifications ‘use’ purpose groups and represent different levels of hazard. They can apply to a whole building, or (where a building is compartmented) to a particular compartment (e.g. a kitchen) in the building and the relevant purpose group should be taken from the main use of the building or compartment. Table 6.8 sets out the purpose group classification.

p.260

p.261

6.0.14.2  Requirements – size of residential buildings

p.262

p.263

p.264

6.0.14.3  Size of annexes

p.265

6.0.15  The use of Robust Details

One of the recommendations of Approved Document E (Resistance to the passage of sound) involves pre-completion sound testing (PCT) for certain types of home. This is an attempt to eliminate the risk of any remedial work being required to completed floor and/or wall constructions (together with the potential for delays in completing the property). Since 2004, Robust Details Ltd is responsible for approving, managing and promoting the use of Robust Details as a method of satisfying Building Regulations.

6.0.15.1  What is a Robust Detail?

Robust Details are high performance separating wall and floor constructions (with associated construction details) that are expected to be sufficiently reliable to not need the check provided by pre-completion testing. The Robust Details Scheme is an alternative to pre-completion sound testing (PCT) of separating walls and floors in new-build joined houses, bungalows and flats, to demonstrate compliance with the relevant minimum Building Regulation performance standards in England, Wales, Scotland and Northern Ireland.

p.266

Robust Details provide builders with a choice of possible construction solutions that have been proven to outperform the standards of Approved Document E, thus eliminating the need for routine PCT. A Robust Detail is only used in connection with Approved Document E and is defined as a separating wall or floor (of concrete, masonry, timber, steel or steel-concrete composite) construction, which has been assessed and approved by Robust Details Ltd.

6.0.15.2  How are Robust Details approved?

In order to be approved, each Robust Detail must be:

p.267

6.0.15.3  How can Robust Details be used?

Builders are only permitted to use Robust Details instead of PCT if the plots concerned have been registered in advance with Robust Details Ltd. Once a plot has been registered, Robust Details Ltd will provide the relevant registration documentation, which will be accepted by all Building Control Bodies as evidence that the builder is entitled to use Robust Details instead of PCT. The builder will then need to select the Robust Detail specific to the walls and/or floors they wish to build from the Robust Details handbook (available from Robust Details Ltd) and produce a site work checklist to show how they will ensure that building work is carried out exactly in accordance with the Robust Detail specifications.

p.268

6.0.15.4  Will there be more Robust Details?

Trade associations, manufacturers or other interested parties may submit applications for new Robust Details, and these will be evaluated and, if found acceptable, approved and published.

6.0.15.5  Where can I obtain more information?

More information is available from Robust Details Ltd (www.robustdetails.com) and full contact information is in the ‘Useful contact names and addresses’ section at the end of this book.

p.269

6.0.16  Site preparation and resistance to contaminants and moisture

Some contaminants can penetrate the floors of buildings, such as landfill gas arising from the deposition of waste and vapours from spills of organic solvents and fuel. These contaminants can also migrate laterally from land outside the building. In order to deal with this, Approved Document C (Site preparation and resistance to contaminates and moisture) now applies to all changes of use that have a residential purpose or provide sleeping accommodation.

The rate at which gas seeps into buildings, mainly through floors, can be reduced by edge-located sumps or subfloor vents. These are less intrusive than internal sumps or ducts that may involve taking up floors. If flagged floors are taken up, the stones should be indexed and their layout recorded to facilitate relaying when work is completed.

Approved Document C gives guidance for the following situations:

p.270

p.271

A floor is an element of structure and should be treated as such.

For the purposes of this section, a floor is considered to be the lower horizontal surface of any space in a building and includes finishes that are laid as part of the permanent construction. The ground floor of a building may be made of solid concrete or suspended timber type. With a concrete floor, a damp-proof membrane is laid between walls.

With timber floors, sleeper walls of honeycomb brickwork are built on oversite concrete between the base brickwork; a timber sleeper plate rests on each wall, and timber joists are supported on them. Their ends may be similarly supported, let into the brickwork or suspended on metal hangers. Floorboards are laid at right angles to joists. First-floor joists are supported by the masonry or hangers.

As with brick-built house, the floors in a timber-framed house may be solid concrete or suspended timber. In some cases, a concrete floor may be screeded or surfaced with timber or chipboard flooring. Suspended-timber floor joists are supported on wall plates and surfaced with chipboard. Guidance on the sizing of timber floors and roofs for traditional house construction known as the Timber Tables are published by TRADA.

p.272

6.1  Foundations

To support the weight of the structure, most brick-built buildings are supported on a solid concrete base which is called the ‘foundation’. Timber-framed houses are usually built on a concrete foundation with a ‘strip’ or ‘raft’ construction to spread the weight. Maintenance on foundations generally does not require planning permission. However, if you live in a listed building or designated area (conservation area, national park or Area of Outstanding Natural Beauty) you should check with your Local Planning Authority before carrying out any work.

The Local Authority is entitled to carry out tests of the soil or subsoil of the site of the building and you can be prosecuted or ordered to carry out remedial work on a property, whether you are the owner or merely the occupier.

Underpinning is a construction method which increases the depth of the foundations of a building by excavating the existing foundations and replacing them with new foundation material. The reasons for underpinning are:

Underpinning work will require very careful planning and execution and (if you propose to underpin an existing foundation) Building Regulations approval will normally be required. In order that you do not undermine the existing foundations, causing further damage to the structure above and raising the possibility of the building collapsing, any excavations for underpinning should be carried out under the instructions of a suitably qualified engineer.

Note: Filling the excavation with concrete will not necessarily guarantee that the underpinning will provide sufficient support to the existing foundations, because of the possibility that cavities will remain between the two. It is, therefore, recommended, and usually necessary, for a sand and cement packing to be rammed into the void in stages, to ensure adequate support. The timing of each stage and the specification of the materials to be used will vary on a case-by-case basis and should normally be the subject of a structural engineer’s design.

p.273

6.1.1  Requirements

Note: For the purpose of this requirement, ‘contaminant’ means any substance which is, or may, become harmful to persons or buildings, including substances that are corrosive, explosive, flammable, radioactive or toxic.

p.274

6.1.2  Meeting the requirements

6.1.2.1  Structure

6.1.2.1.1  Structural safety

6.1.2.1.2  Ground movement

Note: The reports from these reviews, which include 1:250,000 scale maps showing the distribution of the physical constraints, are available from a number of licence holders, including the British Geological Survey.

6.1.2.1.3  Basic requirements for stability

p.275

Note: A traditional cut-timber roof (such as one using rafters, purlins and ceiling joists) generally has sufficient built-in resistance to instability and wind forces (e.g. from hipped ends, tiling battens and rigid sarking). However, the need for diagonal rafter bracing equivalent to that recommended in BS EN 1995–1-1 should be considered, especially for single-hipped and non-hipped roofs of greater than 40° pitch to detached houses.

6.1.2.1.4  Residential buildings not more than three stories and their annexes

p.276

p.277

6.1.2.1.4.1  annexes

6.1.2.1.5  Maximum floor area

p.278

6.1.2.1.6  Heights of walls and storeys

p.279

p.280

6.1.2.1.7  Foundations – plain concrete

p.281

p.282

Note: This depth will commonly need to be increased in areas subject to long periods of frost or in order to transfer the loading onto satisfactory ground.

Note: Steps in foundations should not be of greater height than the thickness of the foundation.

p.283

The projection X should never be less than the value of P where there is no local thickening of the wall.

6.1.2.1.8  Strip foundations

The most common signs that foundations have problems are hairline cracks or fractures in walls, buckling or crumbling walls, evidence of water damage, sagging floors or warped ceilings, and badly fitting doors and windows.

p.284

6.1.2.2  Site preparation and resistance to contaminants and water

6.1.2.2.1  Hazards associated with the ground

Note: The Contaminated Land (England) Regulations 2006 (as amended 2012) empowers Local Authorities to oversee the management of cause and effects of land contamination and this process is subject to controls under the Town and Country Planning Acts, and guidance in the National Planning Policy Framework.

Construction activities undertaken as part of building development can alter the gas regime on the site (e.g. a site strip can increase surface gas emissions, as can piling and excavation for foundations, and dynamic compaction can push dry biodegradable waste into moist, gas-active zones). General excavation work for foundations and services can also alter groundwater flows through the site. Potential problems include:

6.1.2.2.2  Contaminated ground

Potential building sites which are likely to contain contaminants can be identified at an early stage from planning records or from local knowledge (e.g. previous usage and users). In addition to solid and liquid contaminants, problems can also arise from natural contamination such as methane and the radioactive radon gas (and its decay product). Contaminated land may previously have been used as a factory, mine, steel mill or landfill. Sites which are classed as ‘special sites’ includes land that:

p.285

The Environment Agency produces technical guidance on special sites and these are regulated by the Environment Agency in England, Natural Resources Wales in Wales and the Scottish Environment Protection Agency (SEPA) in Scotland.

Land is legally defined as ‘contaminated land’ where substances are causing, or could cause, significant harm to people, property or protected species, significant pollution of groundwater or other harm to people as a result of radioactivity. It is the responsibility of the Environment Agency or Local Authority to decide if land is contaminated and how the problem should be dealt with, to ask the responsible person to deal with the contamination and to tell them what to do (e.g. fence it off).

Who is responsible for any contamination and how they should deal with it will depend on whether the land is legally considered ‘contaminated land’. If the land counts as contaminated land the person who is normally responsible for dealing with the contamination is usually the person who caused or allowed the contamination to happen. If this person cannot be identified or the agency investigating the issue decides they are exempt, then that agency will then decide who is responsible for dealing with the problem (this can be the person who uses the land or the landowner).

If the person responsible does not deal with the contamination, the Local Authority or agency will send them a ‘remediation notice’, telling them when they must take care of it by.

You can agree a voluntary scheme with the Local Authority or agency if you are responsible for part or all of the clean up. You must state what steps you will take to clean up the land. If you are developing the land you will need to deal with the contamination either before you get planning permission or as part of the development.

p.286

Note: Whatever the situation, you are advised to contact your Local Authority to check what you must do to make sure the land is suitable for any proposed development. More advice can be found at www.gov.uk/government/collections/land-contamination-technical-guidance.

A preliminary site assessment is required to provide information on the past and present uses of the site and surrounding area that may give rise to contamination (see Table 6.1.3).

The Planning Authority should be informed prior to any intrusive investigations or if any substance is found which was not identified in a preliminary statement about the nature of the site.

p.287

6.1.2.2.3  Gaseous contaminants?

6.1.2.2.3.1  radon

Radon (measured in becquerels per cubic metre of air or Bq m^-3) is a colourless, odourless, naturally occurring radioactive gas formed by decaying uranium that occurs naturally in all rocks and soils. Normally the gas that escapes from rock or soil is immediately diluted by the atmosphere and thus poses no harm to humans. However, when radon is trapped in an enclosed space, it can seep out of the ground and build up in houses, other buildings, and indoor workplaces, and studies have established that exposure to radon is the second largest cause of lung cancer in the UK after smoking. Some parts of the country (in particular, England’s West Country) have higher natural levels than elsewhere, and precautions against radon may be necessary.

Essentially a house acts as a chimney. Air rises through the house as it warms and also due to the suction effects on the roof caused by wind action. The warm air eventually finds its way out via gaps at the top of the house. This air is then replaced by more air entering lower down in the house. The highest levels of radon are generally found in the early hours of the morning and in the middle of winter – in other words, the coldest times, when buildings are tightly closed.

p.288

The average level in UK homes is 20 Bq m^-3 and, for levels below 100 Bq m³, individual risk remains relatively low and not a cause for concern; however, the risk increases as the radon level increases.

p.289

Guidance on whether an area is susceptible to radon (and appropriate protective measures) can be obtained from BRE Report BR 211 Radon: Protective measures for new buildings (2015). The report applies to all new buildings, extensions, conversions and refurbishment for domestic or non-domestic use (unless subject to local exemptions contained within the above Regulations. The UK Radon Association has an online interactive map showing areas at risk.

An alternative approach to using these maps would be to obtain a radon risk report. The following services are available:

These services are available from:

•    UK Radon (www.UKradon.org), for small domestic and workplace buildings (and extensions) that have an existing postal address

•    British Geographical Survey Georeports (shop.bgs.ac.uk/georeports) for other development sites.

The radon risk reports will provide a more accurate assessment of whether radon protective measures are necessary and, if needed, the level of protection that is appropriate.

The estimated costs for protecting dwellings against radon is not prohibitive and should be considered. Some work can be completed by the average DIY enthusiast while other work requires more specialist intervention. The UK Radon Association estimates that costs are likely to run from £800–£2000 but more details can be found at www.radonassociation.co.uk/guide-to-radon/information-for-house-buyers-and-seller and in the table below.

6.1.2.2.3.2  landfill gas

Landfill gas is generated by the action of anaerobic micro-organisms on biodegradable material in landfill sites, and generally consists of methane and carbon dioxide together with small quantities of VOCs (volatile organic compounds), which give the gas its characteristic odour. Landfill gas can migrate under pressure through the subsoil and through cracks and fissures into buildings.

p.290

Methane and carbon dioxide can also be produced by organically rich soils and sediments such as peat and river silts, and a wide range of VOCs can be present as a result of petrol, oil and solvent spillages.

All will require careful analysis.

6.1.2.2.4  Site investigation

Site investigation is now the recommended method for determining how much unsuitable material should be removed before commencing building work. This investigation will normally consist of well-defined stages, for example those shown in Table 6.1.5.

6.1.2.2.5  Risk assessment

The site investigation may identify certain risks, which will require a risk assessment. There are three types of risk assessment:

Table 6.1.6 shows what each risk assessment should include.

p.291

Where the site is potentially affected by contaminants, a combined geotechnical and geo-environmental investigation should be considered.

6.1.2.2.6  Flood resistance

Although flood resistance is not currently a requirement of the Building Regulations, as part of its aim to improve the energy efficiency of buildings and use planning to protect the environment, the policies set out in the revised 2012 National Planning Policy Framework suggest that Local Planning Authorities should adopt proactive strategies to mitigate and adapt to climate change, taking full account of flood risk, coastal change and water supply demand considerations (see www.gov.uk/guidance/national-planning-policy-framework/10-meeting-the-challenge-of-climate-change-flooding-and-coastal-change).

p.292

6.1.2.2.7  Gaseous risk assessment

A risk assessment based on the concept of a ‘source–pathway–receptor’ relationship, or pollutant linkage of a potential site (see Figure 6.1.13) should be carried out to ensure the safe development of land that is affected by contaminants.

p.294

6.1.2.2.8  Ground investigation

Note: During the development of land affected by contaminants, the health and safety of both the public and workers should be considered.

6.1.2.2.9  Remedial measures

6.1.2.2.10  Corrective measures

Depending on the contaminant, three generic types of corrective measure can be considered: treatment, containment and/or removal.

Note: The containment or treatment of waste may require a waste management licence from the Environment Agency.

p.295

6.1.2.2.11  Treatment

The choice of the most appropriate treatment process is a highly site-specific decision for which specialist advice should be sought.

6.1.2.2.12  Containment

6.1.2.2.13  Removal

6.1.2.2.14  Site preparation

Where mature trees are present (particularly on sites with shrinkable clays; see Table 6.1.7) the potential damage arising from ground heave to services and floor slabs and oversite concrete should be assessed.

6.1.2.2.15  Foundations and types of soil

Table 6.1.8 provides guidance on determining the type of soil on which it is intended to lay a foundation.

6.1.2.2.16  Subsoil drainage

p.296

6.1.2.2.17  Building size

Many of the provisions in the Approved Document C (Site preparation and resistance to contaminates and moisture) are related to how the building is going to be used, its purpose and who is going to use it. These provisions can apply to a whole building or (where a building is compartmented) to a section of a building. Table 6.1.9 sets out the purpose group classifications.

p.297

6.1.2.3  Drainage and waste disposal

6.1.2.3.1  Rainwater drainage

6.1.2.3.2  Foul drainage

6.2  Ventilation

Ventilation is defined in the Building Regulations as ‘the supply and removal of air (by natural and/or mechanical means) to and from a space or spaces in a building’.

The adoption of any ventilation measure should not involve unacceptable technical risk, for instance, creating a cold bridge. Designers and builders should refer to the relevant Approved Documents and to other generally available good practice guidance to help minimize these risks. In addition to replacing ‘stale’ indoor air with ‘fresh’ outside air, the aim of ventilation is to:

p.300

In general terms, all these aims can be met if the ventilation system:

6.2.1  Requirements

p.301

p.302

p.303

p.304

6.2.2  Meeting the requirements

6.2.2.1  Structure

6.2.2.1.1  Openings and recesses

Note: The value of the X factor should be taken from Table 6.2.1. Alternatively, X may be given the value 6 provided the declared compressive strength of the bricks or blocks is not less than 7.3N/mm².

p.305

6.2.2.2  Fire safety

If ventilation ducts pass through compartment walls into another building, then the guidance given in Approved Document B Volume 2 (Fire safety) should be followed.

In dwellings with three or more storeys and blocks of flats, passive stack ventilation ducts should not impede fire escape routes.

Note: A floor level with a gradient of 1:20 or steeper should be designed as a ramp.

p.306

6.2.2.3  Site preparation and resistance to moisture

6.2.2.3.1  Historic buildings

When working in historic buildings, to ensure that moisture ingress to the roof structure is limited and the roof can breathe, try to provide dedicated ventilation to pitched roof. If this is not possible, seal existing service penetrations in the ceiling and to provide draught proofing to any loft hatches. Any new loft insulation should be kept sufficiently clear of the eaves so that any adventitious ventilation is not reduced.

6.2.2.3.2  Radon

Radon can be dispersed by ventilation strategies such as positive pressurization. These systems can often be accommodated in an unobtrusive manner.

6.2.2.3.3  Remedial measures

6.2.2.3.4  Suspended timber ground floors (moisture from the ground)

p.307

6.2.2.3.5  Cladding

6.2.2.3.6  Roofs

6.2.2.4 Resistance to the passage of sound

There are requirements for ventilation of ducts at each floor where they contain gas pipes. Gas pipes may be contained in a separate ventilated duct or they can remain unenclosed. Where a gas service is installed, it shall comply with relevant codes and standards to ensure safe and satisfactory operation. See the Gas Safety (Installation and Use) Regulations 1998, SI 1998 No. 2451.

6.2.2.5 Ventilation

The aim of Approved Document F (Ventilation) is to suggest to the designer the level of ventilation that should be sufficient for a particular situation, as opposed to how it should be achieved. The designer is, therefore, free to use whatever ventilation system they consider most suitable for a building, provided that it can be demonstrated that it meets the recommended performance criteria and levels concerning moisture, pollutants and air flow rate standards as shown in Table 6.2.2.

For further details and examples concerning ‘performance-based ventilation’ are contained in Appendix A to Approved Document F.

6.2.2.5.1 General requirements

Note: This notification would usually be by way of a Full Plans application or a building notice given to a Local Authority, or an initial notice given jointly with the Approved Inspector.

p.308

Note: It is not necessary to notify a BCB in advance of work which is to be carried out by a person registered with a competent person self-certification scheme for that type of work. There are several competent person schemes for the installation of mechanical ventilation and air-conditioning systems in buildings (see www.communities.gov.uk and Chapter 2).

Where the work is of a minor nature as described in the schedule of non-notifiable work, the work must still comply with the relevant requirements but need not be notified to the BCB. Such work includes:

In most cases where it is proposed to carry out notifiable ventilation work on a building, the BCB has to be notified in advance via a Full Plans application or an initial notice given jointly with the Approved Inspector.

6.2.2.5.2  Historic buildings

Ventilation systems should not introduce a new or increased technical risk, or in any other way prejudice the use or character of the building, particularly historic buildings that are:

When undertaking work on, or in connection with, a building that falls within one of the classes above, the aim should be to provide adequate ventilation as far as is reasonably and practically possible without damaging the character of the building or increasing the risk of long-term deterioration of its fabric or fittings.

Many books have been written about the problems related to restoring historic buildings and, before considering any work of this nature, you would be advised to seek the advice of the Local Planning Authority’s Conservation Officer, particularly if you are contemplating:

In all cases, the overall aim should be to improve ventilation of a historic building without:

Note: The guidance given by English Heritage1 and in BS 7913 Principles of the conservation of historic buildings should be taken into account in determining appropriate ventilation strategies for building work in historic buildings.

6.2.2.5.3  Live-work units

6.2.2.5.4  performance of ventilation system

The key aim of the requirement is that a ventilation system is provided which, under normal conditions, can limit the accumulation of moisture which could lead to mould growth, and pollutants originating within a building which would otherwise become a hazard to the health of the people in the building. This requirement may be achieved by providing a ventilation system which:

The use of ventilation systems in buildings result in energy being used to heat fresh air taken in from outside and, in mechanical ventilation systems, to move air into, out of and/or around the building. Consideration, therefore, should be given to employing heat recovery devices, efficient types of fan motor and/or energy-saving control devices in the ventilation system.

6.2.2.5.5  The purpose of ventilation

Common pollutants in a dwelling are moisture and combustion products from unflued appliances (e.g. gas, oil or solid fuel cookers) and chemical emissions from construction and consumer products.

Note: The ventilation system capacity, if used appropriately, is usually sufficient to remove odours arising from normal occupant activities within a dwelling.

6.2.2.5.6  Types of ventilation

Note: The ventilation systems and devices mentioned in this book are examples of those most commonly in use at the time of writing. Other ventilation systems and devices could provide acceptable solutions. Where this is the case, you should seek the advice of your BCB.

Trickle ventilators are intended to normally be left open in occupied rooms in dwellings. Trickle ventilators with automatic controls should also have a manual override, so that the occupant can close the ventilator to avoid draughts. For pressure-controlled trickle ventilators that are fully open at typical conditions (e.g. 1 Pa pressure difference), only a manual close option is recommended.

In dwellings, humidity-controlled devices should be available to regulate the humidity of the indoor air, and hence minimize the risk of condensation and mould growth. These are best installed as part of an extract ventilator in moisture-generating rooms (e.g. kitchen or bathroom). Humidity control is not considered appropriate for sanitary accommodation, where the dominant pollutant is normally odour. Other types of automatic control (e.g. trickle ventilators, ventilation fans, dampers and air terminal devices) may also be suitable for regulating ventilation devices in dwellings.

Buildings can currently achieve an air permeability down to around 2–4m³/h.m² of envelope area at 50 Pa pressure difference through good design. However, it is expected to improve in the future owing to the UK’s commitment to higher energy efficiency and lower carbon emissions.

p.312

The three main controllable ventilation methods are listed in Table 6.2.3.

6.2.2.5. 6.1  purge ventilation

Purge ventilation is a manually controlled type of ventilation that is used in rooms and spaces to rapidly dilute pollutants and/or water vapour. It can be achieved by natural means (such as an openable window or an external door) or by mechanical means (e.g. a fan).

Note: For further guidance on purge ventilations, see BS 5925

6.2.2.5.6.2  background ventilators and intermittent extract fans

The need for background ventilators will depend on the air permeability or airtightness of a building, where air permeability is defined as ‘the average volume of air (in cubic metres per hour) that passes through unit area of the building envelope (in square metres) when subject to an internal to external pressure difference of 50 Pa’.

6.2.2.5.7  Ventilation of rooms containing openable windows

A window with a night latch position is not recommended because of the difficulty of measuring the equivalent area, the greater likelihood of draughts and the potential increased security risk in some locations.

p.313

6.2.2.5.8  Control of the ventilation system

Ventilation should be controllable so that it can maintain reasonable indoor air quality and avoid waste of energy. These controls can be either manual or automatic. Manually controlled trickle ventilators can be located over the window frames, in window frames, just above the glass or directly through the wall (see Figure 6.2.4).

Note: Humidity control is not appropriate for sanitary accommodation, where the dominant pollutant is normally odour.

6.2.2.5.9  Ventilation effectiveness

Ventilation effectiveness is (as the term suggests) a measure of how well a ventilation system supplies air to the building’s occupants. From an energy-saving perspective, the higher the level of ventilation effectiveness, the more efficient the system will be in reducing pollutant levels in the occupant’s breathing zone. As this can result in quite significant energy savings, it has to be considered when designing and installing ventilation systems.

As the designer cannot be absolutely certain of the future occupancy and/or use of the building in terms of seating plan, location of computers and printers, etc., a ventilation effectiveness level of 1 (i.e. where the supply air is fully mixed with the room air before it is breathed by the occupants) should be assumed in his calculations.

Note: For more details about ventilation effectiveness, see CIBSE Guide A.

6.2.2.5.10  Noise

Noise (which may travel through ducts) generated by ventilation fans and noise from the fan unit may disturb the occupants of the building and so discourage their use in some circumstances.

The main issues to be addressed in minimizing the noise impact of the ventilation system are the noise from the fan unit entering the ducts, and the attenuation provided by the ducts, bends and junctions and the characteristics of the room grill.

6.2.2.5.11  Ducting

p.314

6.2.2.5.12  Commissioning

6.2.2.5.13  New dwellings

6.2.2.5.13.1  ventilation rates

p.315

6.2.2.5.13.2  extract ventilation requirements

Note: For greater occupancy, add 4 1/s per occupant.

6.2.2.5.13.3  ventilation systems for basements

When ventilating a basement, you should select one of the following ventilation systems (illustrated in Figure 6.2.4).

Table 6.2.7 summarises the requirements for ventilation systems for basements listed below.

p.316

p.317

If the guidance on natural ventilation given in the Approved Document F (Ventilation) is not be appropriate for your situation, seek expert advice.

The guidance in this Approved Document F has not been formulated to deal with the products of tobacco smoking, vaping or other forms of smoking.

6.2.2.5.13.4  ventilation of a habitable room through another room or a conservatory

The general ventilation rate for conservatories (and adjoining rooms) with a floor area greater than 30m², can be achieved by using background ventilators (e.g. air bricks).

6.2.2.5.13.5  kitchens

Note: Manual boost controls should also be provided in kitchens to guard against the possibility of a single centrally located switch being left in an incorrect mode of operation.

6.2.2.5.13.6  exceptions

The guidance in Approved Document F for new dwellings and work on existing buildings does not apply in the following cases:

6.2.2.5.14  Passive stack ventilation

Passive Stack Ventilation (PSV) uses ducts from terminals mounted in the ceiling of rooms to terminals on the roof to extract air to the outside by a combination of the natural stack effect and the pressure effects of wind passing over the roof of the building.

The so-called ‘stack effect’ relies on the pressure differential between the inside and the outside of a building caused by differences in the density of the air due to an indoor–outdoor temperature difference.

p.318

For sanitary accommodation only, purge ventilation may be used if security is not an issue.

6.2.2.5.14.1  PSV design

In designing PSV systems, the following requirements shall be met:

Instead of PSV, an open-flued appliance may provide sufficient extract ventilation.

p.319

The design and installation of PSV systems are crucial to their operation, and Figure 6.2.8 shows the preferred option for kitchen and bathroom ducts with ridge terminals.

p.320

Another option (see Figure 6.2.9) is to have the kitchen and bathroom ducts penetrating the roof and extending their terminals to ridge height.

6.2.2.5.14.2  location of PSVs

Note: Allow approximately 300mm extra to make smooth bends in an offset system.

p.321

6.2.2.5.14.3  PSV controls

6.2.2.5.14.4  PSV terminals and ducts

p.322

Note: Terminals should have an overall static pressure loss (upstream duct static minus test room static) equivalent to no more than four times the mean duct velocity pressure when measured at a static pressure difference of 10 Pa.

p.324

6.2.2.5.14.5  operation of PSVs in hot weather

Although PSV units should be capable of extracting sufficient air from wet rooms during the winter, in the summer months (when the temperature difference between the internal and external air is considerably reduced) they may not. To guard against this happening, purge ventilation should also be provided in wet rooms.

p.325

6.11.2.5.15  Purge ventilation

Note: Appendix B Gives details of window and door sizing.

6.2.2.5.16  External pollution

In urban areas, buildings are exposed to many pollution sources from varying heights and upwind distances (long, intermediate and short-range). Internal contamination from these pollution sources can have a detrimental effect on the buildings’ occupants, and so it is very important to ensure that the ventilation system provided is sufficient and, above all, that the air intake cannot be contaminated.

p.326

Typical urban pollutants include:

Typical emission sources include:

6.2.2.5.17  Indoor air pollutants

The maximum permissible level of indoor air pollutants is listed in Table 6.2.9.

Note: Mould growth can occur whether the dwelling is occupied or unoccupied, so the performance criteria for moisture (see Table 6.2.10) should be met at all times, regardless of occupancy. The other pollutants listed in Table 6.2.9 are harmful to the occupants only when the dwelling is occupied.

Extract ventilation concerns the removal of air directly from a space or spaces to outside. Extract ventilation may be by natural means such as PSV or by mechanical means (e.g. by an extract fan or central system).

Extract fans lower the pressure in a building, which can cause combustion gases from open-flued appliances filling the room instead of going up the flue or chimney.

6.2.2.5.18  Equivalent ventilator area for dwellings

Designers should use the equivalent ventilator areas shown in Table 6.12.11 when designing systems using intermittent extract fans and background ventilators for multistorey dwellings that are more than four storeys above ground level and which have more than one exposed façade.

p.327

Note: Equivalent area is defined as ‘the area of a sharp-edged orifice which air would pass at the same volume flow rate, under an identical applied pressure difference’.

p.328

6.2.2.5.19  Ventilation air intakes

One method of achieving good indoor air quality is to reduce the amount of water vapour and/or air pollutants that are released into the indoor air, particularly those caused from construction and consumer products.

Air intakes that are located on a less polluted side of the building may be used for fresh air.

Note: Further information about control of emissions from construction products is available in BRE Digest 464.

6.2.2.5.20  Installation of fans in dwellings

The three fan types most commonly used in domestic applications are:

Note: The duct must be pulled taut and the discharge terminal should have at least 85 percent free area of the duct diameter.

p.329

6.2.2.5.20.1  fan terminals

When installing fans:

Note: In these cases (only), the equivalent area may be assumed to be equal to the free area.

6.2.2.5.20.2  intermittent extract fans

In rooms with no natural light, the fans could be controlled by the operation of the main room light switch.

p.330

Note: For sanitary accommodation, a purge ventilation system may be used, and in wet rooms a heat recovery ventilator may be used instead of a conventional fan, if it has the same extract rate.

p.331

p.332

6.2.2.5.21  Location of background ventilators in rooms

6.2.2.5.22  Trickle ventilators

Manually controlled trickle ventilators are widely used for background ventilation and these can be located as shown in Figure 6.2.15.

To avoid cold draughts, trickle ventilators are normally positioned 1.7m above floor level, and usually include a simple control (such as a flap) to allow users to shut off the ventilation according to personal choice or external weather conditions. Nowadays, pressure-controlled trickle ventilators that reduce the air flow according to the pressure difference across the ventilator are available to reduce draught risks during windy weather.

Trickle ventilators are normally left open in occupied rooms in dwellings.

p.333

6.2.2.5.23  Continuous mechanical extract

This system may consist of either a central extract system or individual room fans, or a combination of both.

To calculate the required extract rate, first determine the whole-building ventilation rate from Table 6.2.5.

For sanitary accommodation only, purge ventilation may be used if security is not an issue.

p.334

6.2.2.5.23.1  continuous mechanical extract – requirements

Where ducts etc. are provided in a dwelling with a protected stairway, precautions may be necessary to avoid the possibility of the system allowing smoke or fire to spread into the stairway.

6.2.2.5.23.2  continuous mechanical supply and extract with heat recovery

To calculate the air flow rate of a building using continuous mechanical supply and extract with heat recovery (i.e. MVHR), first determine the whole-building ventilation rate from Table 6.2.5 then, depending on whether it is a multistorey or single-storey building, subtract the gross internal volume of dwelling heated space (m²) as follows:

6.2.2.5.24  Mechanical intermittent extract

As odour is the main pollutant, humidity controls should not be used for intermittent extract in sanitary accommodation.

p.335

Note: In dwellings, humidistat controls should be available to regulate the humidity of the indoor air and, to minimize the risk of condensation and mould growth, should be installed as part of an extract ventilator, especially in moisture-generating rooms such as a kitchen or a bathroom. They should not be used for sanitary accommodation, where the dominant pollutant is usually odour.

p.336

6.2.2.5.24.1  operation

Note: Extract terminals located on the prevailing windward façade should be protected against the effects of wind by using ducting to another façade, using a constant-volume flow rate unit or a central extract system.

p.338

p.339

6.2.2.5.25  The effects of solar gains in summer

Solar gains are certainly beneficial in winter, as they reduce the demand for heating. However, they can cause overheating in the summer.

To overcome this problem during the summer (and whenever possible), the effects of solar gain should be limited by a suitable combination of window size and orientation, shading, solar control measures, ventilation (day and night) and high thermal capacity.

If ventilation is provided using a balanced mechanical system, consideration should be given to providing a summer bypass function for use during warm weather (or allow the dwelling to operate via natural ventilation) so that the ventilation is more effective in reducing overheating.

Although many buildings are equipped with air-conditioning for comfort, these are high energy users and their use should, whenever possible, be limited. This can be achieved by either reducing the need for air-conditioning or reducing the installed capacity of any air-conditioning system that is installed.

6.2.2.5.26  Access for maintenance

6.2.2.5.27  Exhaust outlets

Exhaust outlets should be located so that re-entry, or ingestion, into the building and/or other nearby buildings is minimized. This can be achieved by ensuring that:

p.340

Note: Where possible, pollutants from stacks should be grouped together and discharged vertically upwards.

6.2.2.5.28  Work on existing buildings

Under the Building Regulations, windows are a controlled fitting. These clauses, therefore, make it mandatory that, when windows in an existing building are replaced, then the replacement work:

6.2.2.5.28.1  replacement windows

p.341

Note: The window opening area is the dimensions of the open area: height (H) × width (W).

p.342

Note: Approved Document B (Fire safety) includes provisions for the size of escape windows. The larger of the provisions in Approved Document B or F (Ventilation) should apply in all cases.

6.2.2.5.28.2  the addition of a habitable room

The general ventilation rates for an additional habitable room (not including a conservatory) to an existing building may be achieved by using background ventilators, heat recovery ventilators and/or purge ventilation.

p.343

6.2.2.5.28.3  single room heat recovery ventilator

If a Single Room Heat Recovery Ventilator (SRHRV) is used to ventilate a habitable room, to calculate the air flow rate, first determine the whole-building ventilation rate from Table 6.2.5, and then work out the room supply rate using the following formula:

When working out the continuous mechanical extract for a whole building, which also includes a room ventilated by an SRHRV, the following formula should be used:

6.2.2.5.28.4  the addition of a wet room to an existing building

p.344

6.2.2.5.29  Roofs

6.2.2.5.29.1  roof with a pitch of 15° or more

Pitched roof spaces should have ventilation openings at least 10mm wide at eaves level to promote cross-ventilation. A pitched roof that has a single slope and abuts a wall should have ventilation openings at eaves level at least 10mm wide and at high level (i.e. at the junction of the roof and the wall) at least 5mm wide.

Roof spaces should have ventilation openings at least 25mm wide in two opposite sides to promote cross-ventilation. The void should have a free air space of at least 50mm between the roof deck and the insulation. Pitched roofs where the insulation follows the pitch of the roof need ventilation at the ridge at least 5mm wide.

Where the edges of the roof abut a wall or other obstruction in such a way that free air paths cannot be formed to promote cross-ventilation, or the movement of air outside any ventilation openings would be restricted, an alternative form of roof construction should be adopted.

Roofs with a span exceeding 10m may require more ventilation totalling 0.6 percent of the roof area.

Ventilation openings may be continuous or distributed along the full length and may be fitted with a screen, fascia, baffle, etc.

Where necessary (e.g. for the purposes of health and safety), ventilation to small roofs such as those over porches and bay windows should always be provided and a roof that has a pitch of 70° or more shall be insulated as though it were a wall.

If the ceiling of a room follows the pitch of the roof, ventilation should be provided as if it were a flat roof.

p.345

6.2.2.5.29.2  passive stack ventilation in roof spaces:

Note: Placing the outlet terminal at the ridge of the roof is the preferred option, as it is not prone to wind gusts and/or certain wind directions.

p.346

6.2.2.5.30  Existing buildings

The requirements for ventilation to an existing building which is going to have an additional habitable room (not including a conservatory) will depend on whether the existing building has windows opening to outside and the amount of background ventilation it possesses. Basically:

6.2.2.5.30.1  the addition of a conservatory to an existing building

If a conservatory is added to an existing habitable room which does not have windows opening to the outside, then the habitable room may be ventilated through the conservatory provided that there is background ventilation of at least 8000mm² equivalent area between the habitable room and the conservatory, and background ventilation of at least 8000mm² equivalent area between the additional room and outside.

p.347

6.2.2.5.30.2  refurbishing a kitchen or bathroom in an existing dwelling

If any of the work being carried out in the kitchen of an existing building is ‘building work’ then you will need to comply with the appropriate requirements of this Regulation.

p.348

Note: The guidance within the Approved Document F may not be adequate to address pollutants from flueless combustion space heaters or from occasional, occupant-controlled events such as painting, smoking, cleaning or other high-polluting events. Extract ventilation may be by natural means (e.g. by PSV or by mechanical means such as an extract fan or central system).

6.2.2.6  Drainage and waste disposal

6.2.2.7  Combustion appliances and fuel storage systems

6.2.2.7.1  Ensuring adequate ventilation

p.349

6.2.2.7.2  Permanently open air vents

p.350

p.351

Note: A way to meet the requirement would be to size permanently open air vents so that their equivalent area is sufficient for the appliance(s) to be installed (taking account where necessary of obstructions such as grilles and anti-vermin mesh), and to site them:

p.352

6.2.2.7.3  Noise attenuation

6.2.2.7.4  Transfer ventilation

6.2.2.7.5  Ventilation ducts

6.2.2.7.6  Flueless appliances

Note: Openable elements installed for the rapid ventilation of rooms, and other provisions made for the rapid ventilation of kitchens, may be acceptable for flueless appliances in those locations.

Ways of meeting the requirement when installing flueless cookers (including ovens, grills or hotplates), flueless water heaters and flueless space heaters are shown in Figure 6.2.22.

p.353

6.2.2.7.7  Extract ventilation

6.2.2.7.8  Flued appliances other than decorative fuel-effect fires

p.354

6.2.2.7.9  Airtightness of the dwelling

p.355

Individual rooms in some older houses with solid walls and solid floors can be inherently airtight when fitted with modern glazing. The situation may, therefore, need to be assessed with respect both to the overall dwelling and to the individual room where the appliance is to be fitted.

p.356

If in doubt, assume that the air permeability is lower than 5.0m³/ (h.m²) at 50 Pa and fit the appropriate permanent ventilation or seek specialist advice. (Further information can be found in GPG224 Improving airtightness in dwellings).

p.357

6.2.2.7.10  Ventilation of LPG and oil storage tanks

Thatched roofs can sometimes be vulnerable to spontaneous combustion caused by heat transferred from flues building up in thick layers of thatch that are in contact with the chimney. To reduce the risk, it is recommended that rigid twin-walled insulated metal flue liners are used within a ventilated (top and bottom) masonry chimney void, as long as they are adequately supported and not in direct contact with the masonry. Non-metallic chimneys and cast in-situ flue liners can also be used if the heat transfer to the thatch is assessed in relation to the depth of thatch and risk of spontaneous combustion.

p.358

6.2.2.8  Protection from falling, collision and impact

Regulations regarding the requirements for opening, closing or adjusting windows, skylights and ventilators are also contained in Regulation 15(1) of the Workplace (Health, Safety and Welfare) Regulations 1992.

p.359

6.2.2.9  Conservation of fuel and power

Note: The ‘energy performance of a building’ means the calculated or measured amount of energy needed to meet the energy demand associated with a typical use of the building, which includes, inter alia, energy used for heating, cooling, ventilation, hot water and lighting.

p.360

For ventilation systems, an approved procedure would be to follow the guidance in the Domestic Ventilation Compliance Guide.

p.361

6.3  Drainage

6.3.1  Requirements

p.362

p.363

6.3.2  Meeting the requirements

6.3.2.1  Fire safety

6.3.2.1.1  Openings in compartmentation and cavity barriers

p.364

6.3.2.1.2  Openings for pipes

p.365

6.3.2.1.3  Fire-stopping

6.3.2.2  Site preparation and resistance to moisture

6.3.2.2.1  Subsoil drainage

6.3.2.2.2  Flood risk

p.366

Note: Flooding can create blockages in drains and sewers that can lead to backflow of sewage into properties through low-level drain gullies, toilets, etc.

6.3.2.2.3  Protection against groundwater

6.3.2.2.4  External walls

p.367

6.3.2.2.5  Joints between doors and windows

p.368

6.3.2.2.6  Roofs

6.3.2.3  Resistance to the passage of sound

6.3.2.3.1  Junction requirements for walls and floors

To reduce flanking transmission and avoid air paths, pay special attention to workmanship and detailing at the perimeter and wherever a pipe or duct penetrates the floor.

p.369

6.3.2.4  Sanitation, hot water safety and water efficiency

6.3.2.4.1  Non-notifiable work

6.3.2.4.2  Discharge to drains

p.370

Note: Where greywater recycling is used, lower overall flows are to be expected (particularly at the head of the drain) this should be taken into account in drain design.

6.3.2.5  Drainage and waste disposal

Laying and maintaining drains are hazardous operations. Appropriate safety codes should be followed including procedures for working in confined spaces. Safe working procedures and permits to work may be required in some situations.

6.3.2.5.1  Sanitary pipework

6.3.2.5.1.1  traps

Note: All points of discharge into the system should be fitted with a trap (e.g. a water seal) to prevent foul air from the system entering the building.

p.371

6.3.2.5.1.2  branch discharge pipes

Note: If an appliance is on the ground floor, the pipe(s) may discharge to a stub stack, discharge stack, direct to a drain or (if the pipe carries only wastewater) or a gully.

In single dwellings (up to three storeys) branch discharge pipes should not discharge into a stack lower than 450mm above the invert of the tail bend at the foot of the stack. In certain cases a stub stack may be used (see Figure 6.3.6).

Note: A branch pipe serving a ground floor appliance may discharge direct to a drain or into its own stack.

p.372

p.373

p.374

p.375

Note:

p.376

A separate ventilating stack is only likely to be preferred where the numbers of sanitary appliances and their distance to a discharge stack are large.

p.377

6.3.2.5.1.3  discharge stacks

6.3.2.5.1.4  materials for pipes fittings and joints

p.378

6.3.2.5.2 Foul drainage

‘Foul drainage’ includes all underground drains and sewers from buildings to the point of connection to an existing sewer or a cesspool or wastewater treatment system plus any drains or sewers outside the curtilage of the building.

You should make sure pipework is well maintained at all times as defective pipework is known to harbour rats.

p.379

Note: Anti-flooding valves should preferably be of the double valve type, and should be suitable for foul water and have a manual closure device.

Pipes should (wherever possible) be laid in straight lines. Changes of direction and gradient should be minimized.

p.380

Drainage serving kitchens in commercial hot food premises should be fitted with a grease separator complying with BS EN 1825–1.

6.3.2.5.2.1  rodent control

If the site has been previously developed, the Local Authority should be consulted to determine whether any special measures are necessary for control of rodents. Special measures which may be taken include:

p.381

6.3.2.5.2.2  protection from settlement

Note: Where pipes are to be laid on piles or beams or in a common trench, or where the ground may prove unstable, particularly where there is a high water table, advice may be found in TRL’s A Guide to the Design Loadings for Buried Rigid Pipes. The Local Authority may be able to provide information regarding the site.

p.382

p.383

6.3.2.5.2.3  pipe gradients and sizes

p.384

6.3.2.5.2.4  pumping installations

Where gravity drainage is impracticable, or protection against flooding due to surcharge in downstream sewers is required, a pumping installation will be needed.

Note: Package pumping installations suitable for installation within buildings are available and floor-mounted units may be particularly suited for installing in basements.

Although flood resistance is not currently a requirement of the Building Regulations, as part of its aim to improve the energy efficiency of buildings and use planning to protect the environment, the revised 2013 National Planning Policy Framework sets out policies that aim to avoid inappropriate development in areas at risk of flooding, including requiring new development to be flood resilient and resistant, as and where appropriate. See www.gov.uk/government/uploads/system/uploads/attachment_data/file/6077/2116950.pdf for full details.

Further information on flood-resistant and -resilient construction can be found in the Defra 2007 publication Improving the Flood Performance of New Buildings: Flood Resilient Construction.

6.3.2.5.25  bedding and backfill

Pipes need to be protected from damage, particularly pipes which could be damaged by the weight of backfilling.

p.385

Special precautions should be taken to take account of the effects of settlement where pipes run under or near buildings.

The depth of the pipe cover will usually depend on the levels of the connections to the system and the gradients at which the pipes should be laid and the ground levels.

p.386

p.387

6.3.2.5.2.6  access points

Sufficient and suitable access points should be provided for clearing blockages from drain runs that cannot be reached by any other means.

p.388

Note: Inspection chambers and manholes should have removable non-ventilating covers of durable material (e.g. cast iron, steel, precast concrete or uPVC).

p.389

All pipework carrying greywater for reuse should be clearly marked with the word ‘GREYWATER’.

6.3.2.5.2.7  power to examine and test

6.3.2.5.2.8  repair, reconstruction or alterations to underground drains or sewers

p.390

6.3.2.5.2.9  sealing or removal of disused drains or sewers

Disused drains and sewers offer ideal harbourage to rats and frequently offer a route for them to move between sewers and the surface. The drains and sewers could also collapse, causing subsidence, and the person who completes work that results in any part of a drain becoming permanently disused is responsible for ensuring that the drain is sealed at such points as the Local Authority may direct.

p.391

6.3.2.5.3  Wastewater treatment systems and cesspools

The use of non-mains foul drainage, such as wastewater treatment systems, septic tanks or cesspools, should only be considered where connection to mains drainage is not practicable.

Any discharge from a wastewater treatment system is likely to require consent from the Environment Agency.

6.3.2.5.3.1  septic tanks

Septic tanks provide suitable conditions for the settlement, storage and partial decomposition of solids, which need to be removed at regular intervals. The discharge can, however, still be harmful and will require further treatment from either a drainage field/mound or constructed wetland.

The principle of a septic tank is very simple.

Wastewater flows from the house to the septic tank. The tank is designed to retain wastewater and allow heavy solids to settle to the bottom. These solids are partially decomposed by bacteria to form sludge. Grease and light particles float, forming a layer of scum on top of the wastewater. Baffles installed at the inlet and outlet of the tank help prevent scum and solids from escaping.

A solid pipe leads from the septic tank to a distribution box where the wastewater is channelled into one or more perforated pipes set in trenches of gravel. Here the water slowly seeps into the underlying soil. Dissolved wastes and bacteria in the water are trapped or adsorbed to soil particles or decomposed by micro-organisms. This process removes disease-causing organisms, organic matter and most nutrients. The purified wastewater then moves to the groundwater or evaporates from the soil. Trench systems are the most common type of system used in new home construction.

p.392

p.393

For septic tanks, cesspools, packaged treatment works and drainage fields a notice should be fixed within the building describing the necessary maintenance.

6.3.2.5.3.2  drainage fields and mounds

p.394

p.395

p.396

p.397

6.3.2.5.3.3  packaged treatment works

Packaged treatment works are used where it is either unacceptable or impractical to install a septic tank and a connection to a mains sewer impossible. These plants are particularly useful for situations where intermittent flow, very low flow and seasonal fluctuating flow rates cause serious problems for other sewage treatment systems. They are ideal for campsites and caravan parks and pubs.

The system comprises a small electrically driven plant and is usually contained within a single tank. The waste passes through three stages, initial settlement, biozone (treatment), final settlement before it is discharged into a land drainage system.

6.3.2.5.3.4  cesspools

A cesspool is a watertight tank, installed underground, for the storage of sewage. No treatment is involved.

Note: A filling rate of 150 litres per person per day is assumed, and if the cesspool does not fill within the estimated period the tank should be inspected for leakage.

p.398

Factory-made cesspools and septic tanks are available in glass-reinforced plastic, polyethylene or steel.

6.3.2.5.3.5  greywater and rainwater tanks

Greywater and rainwater tanks should:

6.3.2.4.5  Rainwater drainage

p.399

6.3.2.5.4.1  gutters and rainwater pipes

Although the Building Regulations only actually applies to draining the rainfall from areas of 6m² or more (unless they receive a flow from a rainwater pipe or from paved and/or other hard surfaces), each case should be considered on its own merits separately and a decision made. This particularly applies to small roofs and balconies. Table 6.25 shows the largest effective area that should be drained into the gutter sizes most often used.

For eaves gutters the design rainfall intensity should be 0.021 1/s/m². In some cases, eaves drop systems may be used.

Gutters should be laid with any fall towards the nearest outlet.

p.400

p.401

Gutters and rainwater pipes should be firmly supported without restricting thermal movement.

6.3.2.5.4.2  drainage of paved areas

p.402

6.3.2.5.4.3 surface water drainage

Discharge to a watercourse may require consent from the Environment Agency, which may limit the rate of discharge. Where other forms of outlet are not practicable, discharge should be made to a sewer. For design purposes, a rainfall interval of 0.014 1/s/m² can be assumed as normal.

Note: The following guidance applies to surface water drainage systems for small catchments with impervious areas up to 2 hectares.

p.403

Under Section 85 (Offences concerning the polluting of controlled waters) of the Water Resources Act 1991, it is an offence to discharge any noxious or polluting material into a watercourse, coastal water or underground water. Most surface water sewers discharge to watercourses.

Under Section 111 (Restrictions on use of public sewers) of the Water Industry Act 1991, it is an offence to discharge petrol, chemical, waste steam or any matter likely to damage the drain into any drain or sewer connected to a public sewer.

p.404

6.3.2.5.5  sewers

If the property is connected to the public sewer, that sewer and any shared sewer pipes or pipes beyond the boundary of that property are the responsibility of the local utility company (see Figure 6.3.23).

Responsibilities for sewers and drains changed in October 2011. Before then, you (as owner) were responsible for pipes within your own boundary.

The most common problem with new connections happens when a property has separate pipes for foul water and for rainwater. It is vitally important that these two pipes are connected to the right parts of the public sewer network.

If you are in the process of building a new property or extension that will require a connection to the public sewer, you will need written permission from the utility company responsible before you’re allowed start. This is in addition to planning permission. You should apply for a sewer connection once you have obtained planning permission (or 12 months before you want to connect if planning permission is not required). Once you have received written approval from the utility company, you or your builder must then apply for permission to carry out the work.

Your local utility company will have a section on its website which explains the process in greater detail, together with all the documentation needed to apply. Details of which utility company covers your area can be found on the Water UK website (www.water.org.uk/consumers/find-your-supplier).

The first preference should always be to provide separate foul and surface water sewerage systems. Where ‘combined’ or ‘partially combined’ sewerage is unavoidable, then the design and construction of the shared sewer should be in accordance with the Protocol on Design, Construction and Adoption of Sewers in England and Wales (see archive.defra.gov.uk/environment/quality/water/industry/sewers/documents/sewer-protocol-rev07.pdf for details) to prevent the proliferation of private sewers and the associated problems of ownership and maintenance.

p.405

6.3.2.5.5.1  building over existing sewers

p.406

6.3.2.6  Combustion appliances and fuel storage systems

6.3.2.6.1 Location of flues

p.407

p.408

6.3.2.6.2  Location and support of cylinders

p.409

6.3.2.7  Access to and use of buildings

Where the dwelling provides an accessible bathroom:

p.410

6.4  Cellars and basements

A basement storey is storey with a floor which at some point is more than 1200mm below the highest level of ground adjacent to the outside walls. Basements are not included in counting the number of storeys in a building.

Unless you have the consent of the Local Authority, you are not allowed to construct a cellar or room in (or as part of) a house, an existing cellar, a shop, inn, hotel or office if the floor level of the cellar or room is lower than the ordinary level of the subsoil water on, under or adjacent to the site of the house.

This does not, however, apply to the construction of a cellar or room carried out in accordance with plans deposited on an application under the Licensing Act 2003.

6.4.1  Requirements

If the owner of the dwelling allows a cellar (or room forming part of it) to be used in a manner known to be in contravention of the Building Regulations, they are liable, on summary conviction, to a fine.

p.411

6.4.2  Meeting the requirements

6.4.2.1  Fire safety

6.4.2.1 1  Means of escape

6.4.2.1.1.1  emergency egress windows and external doors

p.412

Note:

6.4.2.1.1.2  escape from basements

There is a risk that a single stairway may be blocked by smoke from a fire in the basement or ground storey. If a basement storey has a habitable room, then the dwelling should be compliant with the following.

6.4.2.1.1.3  external escape stairs

A stair up from a basement to ground level may not have a reduced height above the top level of the stair.

6.4.2.1.2  Fire resistance on loadbearing elements

6.4.2.1.3  Venting of heat and smoke from basements

6.4.2.1.4  Standard of fire resistance

The lack of an external wall through which to vent heat and smoke may increase heat build-up and thus affect the duration of a fire, as well as complicating firefighting.

p.413

p.414

6.4.2.1.5  Fire resistance periods

6.4.2.2  Resistance to the passage of sound

6.4.2.2.1  Separating wall junctions

6.4.2.3  Ventilation

Ventilation systems for basements are as follows.

p.415

Note: The guidance on natural ventilation given in Approved Document F may not be appropriate for your specific situation. If this is the case, expert advice should be sought.

If the part of the dwelling above ground has no bedrooms, then, for the purpose of ventilation requirements:

6.4.2.4  Drainage and waste disposal

6.4.2.4.1  Branch discharge pipes

p.416

6.4.2.4.2  Surcharging of drains

In all such cases, the sewerage undertaker should be consulted to determine the extent and possible frequency of the likely surcharge.

6.4.2.4.3  Pumping installations

p.417

6.4.2.5  Combustion and fuel storage appliances

6.4.2.5.1  LPG storage vessels and appliances

6.4.2.5.2  Location and support of cylinders

6.4.2.6  Protection from falling, collision and impact

Guarding should be provided whenever it is considered necessary from the point of view of safety to guard any basement stair.

6.4.2. 6.1  General provisions

p.418

6.4.2.6.1  Handrails for stairs

6.4.2.6.2  Design of guarding for cellars and basements

Guarding should be provided in accordance with the dimensions in Figure 6.4.3.

Note: Typical locations for guarding are shown in Figure 6.4.4 and for further guidance on the design of barriers and infill panels refer to BS 6180.

For further guidance on the design of barriers and infill panels, refer to BS 6180.

6.4.2.7  Security

6.4.2.7.1  General

Ground floor, basement and other easily accessible windows (including easily accessible rooflights) should be secure windows in accordance with 6.4.2.7.2.

p.419

6.4.2.7.2  Design of secure windows

Note: Further advice is available in Secured by Design’s New Homes 2014.

6.4.2.7.3  Installation and fixing of secure windows

6.5  Floors

For the purposes of this section, a floor is considered to be the lower horizontal surface of any space in a building and includes finishes that are laid as part of the permanent construction.

p.420

A floor is an element of structure and should be treated as such.

6.5.1  Requirements

p.421

p.422

p.423

6.5.2  Meeting the requirements

6.5.2.1  Structure

6.5.2.1.1  Basic requirements for stability

6.5.2.1.2  Sizes of certain timber members in floors for dwellings

Softwood timber used for roof construction or fixed in the roof space (including ceiling joists within the void spaces of the roof), should be adequately treated to prevent infestation by the house longhorn beetle (Hylotrupes bajulus). Figure 6.5.2 shows the house longhorn beetle.

Note: Guidance on suitable preservative treatments is given in www.woodworm-info.co.uk/house_longhorn_google.htm?gclid=CIeN2uS91tECFYsy0wodCvQCeA.

6.5.2.1.3  Maximum floor area

As shown in Figure 6.5.3:

p.424

6.5.2.1.4  Lateral support by roofs and floors

p.425

p.426

p.427

6.5.2.1.5  Interruption of lateral support

6.5.2.1.6  Disproportionate collapse

It is important to reduce the sensitivity of the building to disproportionate collapse in the event of an accident, especially:

p.428

whichever is smaller, and should not extend further than the immediate adjacent storeys (see Figure 6.5.8). A 5.1

6.5.2.2  Fire safety

6.5.2.2.1  Material alterations

p.429

6.5.2.2.2  Means of escape

It is important that people can exit from the dwelling safely.

6.5.2.2.2.1  provisions for escape from upper floors not more than 4.5 m above ground level

6.5.2.2.2.2  fire safety – provisions for escape from upper floors more than 4.5 m above ground level

6.5.2.2.3  Fire spread

Note: A ceiling suspended below a floor will contributes to the fire resistance of the floor.

p.430

6.5.2.2.4  Loadbearing elements of structure

6.5.2.2.5  Compartmentation

p.431

6.5.2.2.6  Concealed spaces

Concealed spaces or cavities in the construction of a building provide a ready route for smoke and flame spread e.g. in walls, floors, ceilings and roofs.

6.5.2.2.7  Openings for pipes

p.432

Note: In some circumstances roofs, or parts of roofs, may need to be fire-resisting, e.g. if used as an escape route or if the roof performs the function of a floor.

p.433

6.5.2.2.8  Cavities in floor voids

6.5.2.3  Site preparation and resistance to moisture

6.5.2.3.1  Performance

6.5.2.3.2  Flood risk

Note: Further information on flood-resistant and resilient construction can be found in the publication Improving the Flood Performance of New Buildings – Flood Resilient Construction (see www.gov.uk/government/uploads/system/uploads/attachment_data/file/7730/flood_performance.pdf).

p.434

6.5.2.3.3  Clearance of unsuitable material and resistance to contaminants

Note: BRE Special Digest SD133 provides guidance on investigation, concrete specification and design to mitigate the effects of sulphate attack.

p.435

6.5.2.3.4  Remedial measures

6.5.2.3.5  Subsoil drainage

6.5.2.3.6  Role of floors

p.436

6.5.2.3.7  Ground supported floors – moisture from the ground

The damp-proof course should be continuous with any damp-proof membrane in the walls where there is a risk of moisture from the ground.

Some schools of thought believe that there is a need for an additional damp-proof membrane on top of the insulation to combat interstitial condensation. This, however, raises the question: ‘How can this moisture escape?’ Moisture would, presumably, just sit where it is generated and, if interstitial moisture is not controlled by a vapour membrane, it will surely eventually migrate into the concrete or the insulation!

These points have been put to the Department for Communities and Local Government (DCLG), but unfortunately it has been unable to offer any definite answer – responding only that ‘the intention of Approved Documents is to provide guidance to the more common building situations and, as there may be alternative ways of achieving compliance with the requirements, there is no obligation to adopt any particular solution contained in an Approved Document if the builder prefers to meet the relevant requirement in some other way’.

One of our readers has said that he prefers to employ the insulation below the slab and place a damp-proof membrane between the insulation and the blinding wherever possible (if only for ease of construction), which sounds like a very logical solution.

p.437

Note: The requirement can also be achieved by following the relevant recommendations of BS 8102, which also includes recommendations for floors subject to water pressure.

6.5.2.3.8  Suspended timber ground floors exposed to moisture from the ground

p.438

p.439

To prevent water collecting on the ground covering, either the top should be entirely above the highest level of the adjoining ground or, on sloping sites, consideration should be given to installing drainage on the outside of the upslope side of the building (see Figure 6.5.15).

6.5.2.3.9  Suspended concrete ground floors exposed to moisture from the ground

p.440

6.5.2.3.10  Ground floors and floors exposed from below (resistance to damage from interstitial condensation)

6.5.2.3.11  Floors (resistance to surface condensation and mould growth)

6.5.2.4  Resistance to the passage of sound

6.5.2.4.1  General requirements

Note: The sound insulation values in Table 6.5.3 include a built-in allowance for ‘measurement uncertainty’, and so, if any of these test values are not met, that particular test will be considered as failed.

In these cases, it would be best to seek specialist advice before committing yourself.

6.5.2.4.2  Pre-completion testing

p.441

6.5.2.4.3  Junctions between separating walls and other building elements

6.5.2.4.4  Junctions between floors and walls

Where no guidance is provided you should seek specialist advice.

Requirements for the most common junctions between walls and floors are shown in the relevant paragraphs of Approved Document E (Resistance to the passage of sound) as follows:

p.442

p.443

p.444

6.5.2.4.5  Wall type 1 – solid masonry

p.445

p.446

6.5.2.4.6  Wall type 2 – cavity masonry

6.5.2.4.7  Wall type 3 – masonry between independent panels

p.447

p.448

6.5.2.4.8  Wall type 4 – framed walls with absorbent material

p.449

Note:

6.5.2.4.9  Separating floors and associated flanking constructions for new buildings

There are three types of separating floor, as shown below:

6.5.2.4.9.1  ceiling treatments

Each floor type should use one of the following three ceiling treatments, which are ranked in order of sound insulation performance from A to C, as shown in Table 6.5.5 below.

p.450

Note: For beam and block separating floors, seek advice from the manufacturer.

p.451

Note: The mass per unit area of a floating screed should not be included in the calculation of the mass per unit area of the floor.

Note:

6.5.2.4.9.2  floor type 1 – concrete base with ceiling and soft floor covering

A floor of type 1 consists of a concrete floor base with a soft floor covering and a ceiling. Its resistance to airborne sound mainly depends on:

The following floor types are appropriate. Details of how junctions are to be made are also described.

p.452

Note: See BS EN ISO 140–8 for details of how to measure the sound insulation in buildings and of building elements

p.453

6.5.2.4.9.2.1  Junction requirements for floor type 1

p.454

6.5.2.4.9.2.2  Junctions with floor penetrations (excluding gas pipes)

Pipes and ducts should be in an enclosure (both above and below the floor). In all cases:

6.5.2.4.9.2.3  Junctions with a separating wall type 1

For floor types 1.1C and 1.2C, two possibilities exist.

p.455

p.456

It should be noted that for both types of floor, the base (excluding any screed) should not pass through a separating wall type 1, but there are no restrictions on internal walls meeting a type 1 separating floor.

6.5.2.4.9.2.4  Junctions with a separating wall type 2

p.457

6.5.2.4.9.2.5 Junctions with separating wall type 3

At the time of publication, there is no official guidance available on junctions with a separating wall type 4 and so it would be advisable to seek specialist advice for this type of situation.

6.5.2.4.9.3  floor type 2 – concrete base with ceiling and floating floor

A floor of type 2 consists of a concrete floor base with a floating floor (which in turn consists of a floating layer and a resilient layer) and a ceiling. Its resistance to airborne and impact sound depends on:

p.458

Note: Two floor types (consisting of a floating layer and resilient layer – see below) will meet these requirements. A performance-based approach (type C) is also available, as shown in Table 6.5.7.

Note: For floating floor type C, the floors should have a rigid boarding above a resilient and/or damping layer with a-weighted reduction in impact sound pressure level of not less than 29 dB (see BS EN ISO 717–2 and BS EN ISO 140–8).

p.459

p.460

p.461

6.5.2.4.9.3.2  Junctions with floor penetrations (excluding gas pipes)

p.462

6.5.2.4.9.3.3  Junctions with a separating wall type 1

6.5.2.4.9.3.4  Junctions with a separating wall type 2

p.463

6.5.2.4.10.3.5  Junctions with separating wall types 3

p.464

At the time of publication, there is no official guidance available on junctions with a separating wall type 4 and so it would be advisable to seek specialist advice for this type of situation.

6.5.2.4.9.4.  floor type 3 – timber-frame base with ceiling and platform floor

A floor of type 3 consists of a timber-frame structural floor base with a deck, platform floor (consisting of a floating layer and a resilient layer) and ceiling treatment. Its resistance to airborne and impact sound depends on:

p.465

6.5.2.4.9.4.1  Junctions with an external cavity wall with masonry inner leaf

p.466

Note:

6.5.2.4.9.4.2  Junctions with an external cavity wall with timber-frame inner leaf

6.5.2.4.9.4.3  Junctions with internal framed walls

Currently there is no official guidance available on junctions with an external solid masonry walls or internal masonry walls, so it would be best to seek specialist advice in these situations.

6.5.2.4.9.4.4  Junctions with floor penetrations (excluding gas pipes)

p.467

Note: Independent panels are not required if the mass per unit area of the inner leaf is greater than 375kg/m².

6.5.2.4.9.4.5  Junctions with a separating wall type 3 – masonry between independent panels

6.5.2.4.9.4.6  Junctions with a separating wall type 4 – timber frames with absorbent material

p.468

6.5.2.4.10  Dwelling-houses and flats formed by material change of use

p.469

6.5.2.4.10.1  floor treatment 1: independent ceiling with absorbent material

p.470

Note: This construction involves a separation of at least 125mm between the upper surface of the independent ceiling and the underside of the existing floor construction. However, structural considerations determining the size of ceiling joists will often result in greater separation. Care should be taken at the design stage to ensure that adequate ceiling height is available in all rooms to be treated.

p.471

p.472

6.5.2.4.10.2  floor treatment 2: platform floor with absorbent material

p.473

Note: The lower figure of density for the resilient layer gives the best insulation but a ‘softer’ floor. In such cases, additional support can be provided around the perimeter of the floor by using a timber batten with a foam strip along the top attached to the wall.

p.474

Remember that stairs are subject to the same sound insulation requirements as floors where they perform a separating function.

p.475

6.5.2.4.10.3  junctions with floor penetrations

Note: There are requirements for ventilation of ducts at each floor where they contain gas pipes. Gas pipes may be contained in a separate ventilated duct or they can remain unducted. Where a gas service is installed, it should comply with relevant codes and standards to ensure safe and satisfactory operation (also see the Gas Safety (Installation and Use) Regulations 1998, SI 1998/24).

p.476

6.5.2.4.11  Internal walls and floors in new buildings

p.477

Guidance on layout is provided in BS 8233 which provides guidance on sound insulation and noise reduction for buildings.

Note: Insulation against impact sounds can be improved by adding a soft covering (e.g. carpet).

Note: Insulation against impact sounds can be improved by adding a soft covering (e.g. carpet).

p.478

Note: Insulation against impact sounds can be improved by adding a soft covering (e.g. carpet).

Electrical cables give off heat when in use and special precautions may be required when they are covered by thermally insulating materials (See BRE BR 262, Thermal Insulation: Avoiding risks, Section 2.4).

6.5.2.5  Ventilation

Extensions of buildings at ground level with a floor area less than 30m² by the addition of a conservatory, porch, covered yard, covered way, or carport open on at least two sides do not have to comply with Approved Document F (Ventilation).

p.479

6.5.2.5.1  Air transfer

6.5.2.6  Sanitation, hot water safety and water efficiency

6.5.2.6.1  Branch discharge pipes

p.480

6.5.2.6.2  Pumping installations

6.5.2.6.3  Enclosures and storage areas

6.5.2.7  Combustion appliances and fuel storage systems

Note: BRE Report BR 414 (2001) and BRE Report BR 211 (2007) give guidance on penetration of membranes.

p.481

6.5.2.7.1  Location and shielding of connecting fluepipes

p.482

Note: A way of achieving this would be to provide a change in level.

6.5.2.7.2  Hearths for oil-fired appliances

6.5.2.8  Protection from falling, collision and impact

Note: A floor level with a gradient of 1:20 or steeper should be designed as a ramp.

p.483

6.5.2.9  Conservation of fuel and power

If work is being undertaken on an existing building which has a total useful floor area of over 1000m², then, in addition to the principal works (which must still comply with the energy efficiency requirements detailed in Approved Document L (Conservation of fuel and power), in the normal way), consequential improvements, where technically, functionally and economically feasible, will also have to be completed.

In addition, the standards for new thermal elements should be no worse than those shown in Table 6.5.11.

When undertaking renovation works to thermal elements you should consider the cost effectiveness of achieving the U-value targets. In the case of floors:

p.484

Note: The cost effectiveness of this work is complicated by the size and shape of the floor. In many cases, an uninsulated floor has relatively low U-values in comparison to wall and roofs. It is likely therefore that the addition of insulation is only cost effective where the existing floor U-value is greater than 0.70W/m²K.

6.5.2.10  Access to and use of buildings

6.5.2.10.1  Communal entrances

6.5.2.9.2  Through-floor lifting device provision

Note: Approved Document M is an optional requirement for wheelchair user dwellings.

p.485

6.6  Walls

In a brick-built house, the external walls are loadbearing elements that support the roof, floors and internal walls. These walls are normally cavity walls comprising two leaves braced with metal ties, but older houses will have solid walls, at least 225mm thick. Bricks are laid with mortar in overlapping bonding patterns to give the wall rigidity and a damp-proof course is laid just above ground level to prevent the moisture rising. Window and door openings are spanned above with rigid supporting beams called lintels and the internal walls are either non-loadbearing divisions made from lightweight blocks, manufactured boards or timber studding, or loadbearing structures made of brick or block.

Modern timber-framed house walls, on the other hand, are constructed of vertical timber studs with horizontal top and bottom plates nailed to them. The frames, which are erected either on a concrete slab or a suspended timber platform supported by cavity brick walls, are faced on the outside with plywood sheathing to stiffen the structure. Breather paper is fixed over the top to act as a moisture barrier. Insulation quilt is used between studs. Rigid timber lintels at openings carry the weight of the upper floor and roof. Brick cladding is typically used to cover the exterior of the frame and is attached to the frame with metal ties. Weatherboarding often replaces the brick cladding on upper floors.

p.486

p.487

For the purposes of this section (and the various Approved Documents) a wall includes:

A wall does not include:

A wall common to two or more buildings shall be designed and constructed so that it adequately resists the spread of fire between those buildings. A house in a terrace and a semi-detached house are treated as separate buildings.

Note: When reading this section, you will probably notice that a few of the requirements are also covered in sections 6.5 (Floors) and 6.7 (Ceilings). This has been done in order to save the reader having to constantly turn back and reread a previous page!

6.6.1  Requirements

p.488

p.489

p.490

p.491

6.6.2  Meeting the requirements

6.6.2.1  Structure

6.6.2.1.1  General

Walls should comply with the relevant requirements of BS EN 1996–2 but also see BS EN 1996–1-1+A1 if design strengths (and suitability) of walls using masonry units with different compressive strengths are being considered.

Approved Document A assumes that no floor enclosed by structural walls on all sides exceeds 70m², and that no floor without a structural wall on one side exceeds 36m². If you require guidance relating to site exposure conditions and wind speeds, this is available in Approved Document A (Structure) (Table C of Diagram 7) and is included in Chapter 6.1 of this book.

6.6.2.1.2  Basic requirements for stability

6.2.2.1.3  Thickness of walls in certain small buildings

This section applies to the following building types:

p.492

6.6.2.1.3.1  dimensions of walls

The thickness of the wall depends on the general conditions relating to the building of which the wall forms a part (e.g. floor area, roof loading, wind speed, etc.) and the design conditions relating to the wall (e.g. type of materials, loading, end restraints, openings, recesses, overhangs, lateral floor support requirements, etc.).

Note: Where walls are constructed of bricks or blocks, they shall be in accordance with BS EN 1991–1-4+A1

The recommended thicknesses of different types of walls are given below:

Note: Except for a wall in the lowest storey of a three-storey building that carries the load from both upper storeys, walls should have a thickness as determined by the equation in A2C10 (above) or 140mm, whichever is the greater.

p.493

6.6.2.1.3.2  small building dimensions

p.494

p.495

6.6.2.1.3.3  wall ties

There are two types of wall tie that can be used in masonry cavity walls:

Note:

6.6.2.1.3.4  cavity walls in coursed brickwork or blockwork

p.496

Note:

6.6.2.1.3.5  masonry units – construction and workmanship

Walls should be properly bonded and solidly put together with mortar and constructed of masonry units conforming to the following standards:

p.497

6.6.2.1.3.6  mortar

Mortar should be one of the following:

6.6.2.1.3.7  loading on walls

p.498

6.6.2.1.3.8  end restraint

6.6.2.1.3.8.1  Vertical lateral restraint to walls

Note: Each distinct length is considered to be a supported wall for the purposes of the Building Regulations.

p.499

6.6.2.1.3.8.2  Buttressing walls

If the buttressing wall is not itself a supported wall, its thickness T2 should not be less than:

The length of the buttressing wall should be:

p.500

6.6.2.1.3.8.3  Piers and chimneys providing restrain

The sectional area on plan of chimneys (excluding openings for fireplaces and flues) should be not less than the area required for a pier in the same wall. The overall thickness should not be less than twice the required thickness of the supported wall (Figure 6.6.9).

p.501

6.6.2.1.3.8.4  Openings, recesses, overhangs and chases

6.6.2.1.3.8.5  Chases

p.502

Note: Or, in cavity walls, 1/3 of the thickness of the leaf of the wall.

6.6.2.1.3.8.6  Overhangs

6.6.2.1.3.9  lateral support by roofs and floors

p.503

6.6.2.1.3.9.1  Tension straps

p.504

p.505

6.6.2.1.3.9.2  Gable wall tension straps

p.506

6.6.2.1.4  Wall cladding

Wall cladding presents a hazard if it becomes detached from the building. An acceptable level of safety can be achieved depending on the type and location of the cladding.

Following the Grenfell Tower blaze the UK government launched an independent review of building regulations after tests showed that at least 82 residential high-rises use a combination of insulation and cladding that did not meet fire safety standards.

Note: Guidance on funnelling effects is given in BRE Digest 436, Wind Loading on Buildings: Brief Guidance for Using BS 6399–2.

p.507

Note: Large glass panels in cladding of walls and roofs (where the cladding is not divided into small areas by loadbearing framing) need special consideration. Guidance is given in the Institution of Structural Engineers’ report Structural Use of Glass in Buildings, 1999, and Nickel Sulphide in Toughened Glass, published by the Centre for Window Cladding and Technology, 2000.

Further guidance on cladding is also provided in the following documents:

p.508

6.6.2 2  Fire safety

Proprietary fire-stopping and sealing systems (including those designed for service penetrations) that have been shown by test to maintain the fire resistance of the wall or other element are available and may be used. Other fire-stopping materials include:

6.6.2.2.1  Smoke alarms

There should be a smoke alarm in the circulation space within 7.5m of the door to every habitable room.

6.6.2.2.2  Air-circulation systems in houses with a floor more than 4.5m above ground level

To avoid the possibility of smoke or fire spreading into a protected stairway:

p.509

6.6.2.2.3  Fire spread and internal linings

The choice of materials for walls and ceilings can significantly affect the spread of a fire and its rate of growth, even though they are not likely to be the materials first ignited. It is particularly important in circulation spaces where linings may offer the main means by which fire spreads and where rapid spread is most likely to prevent occupants from escaping. Several properties of lining materials influence fire spread, such as the ease of ignition and the rate at which the lining material gives off heat when burning.

If a door is provided between a dwelling and the garage:

p.510

Note: Fire doors only need to be provided with self-closing devices if they are between a dwelling and an integral garage.

6.6.2.2.3.1  classification of linings

In general terms, the surface linings for walls should meet the classifications given in Table 6.6.6.

Further guidance on wall linings are provided in paragraphs 3.2 to 3.14 of Approved Document B (Fire safety) Volume 1.

6.6.2.2.4  Cavities and concealed spaces

Concealed spaces or cavities in walls, floors, ceilings and roofs will provide an easy route for smoke and flame spread which, because it is hidden, will present a greater danger than would be more obvious from a weakness in the fabric of the building. To overcome this danger, buildings shall be designed and constructed so that the unseen spread of fire and smoke within concealed spaces in their structure and fabric is prevented.

Note: With the introduction of the 2013 (amended) Approved Document B, window and door frames are now only suitable for use as cavity barriers if they are constructed of steel or timber of an appropriate thickness.

p.511

6.6.2.2.5  Provision of cavity barriers

Cavity barriers should be provided in the following locations:

p.512

6.6.2.2.5.1  construction and fixings for cavity barriers

6.6.2.2.5.2  openings in cavity barriers

Openings in a cavity barrier should be limited to the following:

p.513

6.6.2.2.6  Fire resistance and fire-stopping

6.6.2.2.7  Loadbearing elements of structure

‘Elements of structure’ is the term applied to the main structural loadbearing elements, such as structural frames, floors and loadbearing walls. Compartment walls are treated as elements of structure although they are not necessarily loadbearing. External walls, such as curtain walls or other forms of cladding that transmit only self-weight and wind loads and do not transmit floor load are not regarded as loadbearing for the purposes of their resistance to collapse, although they may need fire resistance to satisfy requirement B4.

p.514

p.515

6.6.2.2.8  Compartmentation

The appropriate degree of subdivision depends on:

Note: Adjoining buildings should only be separated by walls, not floors, unless they are fire-resistant.

To prevent the spread of fire within a building, whenever possible:

Note: The lowest floor in a building does not need to be constructed as a compartment floor.

6.6.2.2.8.1  junction of compartment wall with roof

If a fire penetrates a roof near a compartment wall, there is a risk that it will spread over the roof to the adjoining compartment. To reduce this risk, the wall should be:

p.516

6.6.2.2.8.2  openings in compartment walls separating buildings or occupancies

All other openings in compartment walls or compartment floors should be limited to those for:

6.6.2.2.8.3  flats

In buildings containing flats, the guidance in Volume to of Approved Document B (Fire safety) should be used (see Chapter 7.6)

6.6.2.2.8.4  construction of compartment walls

Note: Adjoining buildings should only be separated by walls, not floors.

p.517

Note: Consideration should also be given to the effect of services that may be built into the construction that could adversely affect its fire resistance. For instance, where downlighters, loudspeakers and other electrical accessories are installed, additional protection may be required to maintain the integrity of a wall or floor.

6.6.2.2.9  Ventilation ducts and flues, etc.

p.518

6.6.2.2.10  Construction of an external wall

The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building. In addition, the external walls of the building should have sufficient fire resistance to prevent fire spread across the boundary.

p.519

6.6.2.2.11  Space separation

p.520

p.521

6.6.2.2.11.1  methods for calculating acceptable unprotected area

6.6.2.2.11.1.1  Method 1

Method 1 may be used for small residential buildings.

p.522

Note: In calculating the maximum unprotected area, any areas falling within the limits shown in Figure 6.6.23, which are small unprotected areas in an otherwise protected area of wall, are considered to pose a negligible risk of fire spread and can be disregarded.

6.6.2.2.9.1.2  Method 2

Method 2 may be used for most buildings or compartments for which Method 1 is not appropriate.

p.523

Note: For any building or compartment more than 10m in height, the methods set out in the BRE report External Fire Spread: Building Separation and Boundary Distances can be applied.

The boundary formed by the wall separating a pair of semi-detached houses may be disregarded for the purposes of this Section (but see Section 6.6.2.2.8.1, which deals with roofs passing over the top of a compartment wall).

6.6.2.2.10  Single-storey buildings

Although most elements of structure in a single-storey building may not need fire resistance, fire resistance will be needed if the element:

p.524

6.6.2.3  Site preparation and resistance to moisture.

The base of walls on any site can be damaged by moisture which can rise from the ground, and much more severe problems can arise in sites that are liable to flooding. Substances in the ground, waste matter or sewage may contaminate floodwater and this contaminated water may affect building elements, such as walls.

Driving rain or wind-driven spray from the sea or other water bodies adjacent to the building can penetrate walls directly, or through cracks or joints between elements, and damage the structure or internal fittings or equipment. Surface condensation from the water vapour generated within the building can cause moulds to grow which pose a health hazard to occupants. Interstitial condensation (a form of structural damping that occurs when warm, moist air penetrates inside a wall, roof or floor structure, reaches the dew point and condenses into liquid water) may damage the structure. Spills and leaks of water, in rooms where sanitary fittings or fixed appliances that use water are installed (e.g. bathrooms and kitchens), may also damage walls.

6.6.2.3.1  Foundations

p.525

6.6.2.3.2  Resistance to moisture in walls

Walls can be exposed to moisture in four ways:

A ‘wall’ includes piers, columns and parapets. It also includes chimneys if they are attached to the building. It does not include windows, doors and similar openings, but does include the joint between their frames and the wall. In the following, the term ‘precipitation’ includes the effects of spray blown from the sea or any other body of water adjacent to the building. All walls should:

p.526

External walls should:

For buildings that are used wholly for storing goods and/or provisions, this requirement may not apply.

6.6.2.3.2  Internal and external walls exposed to moisture from the ground

p.527

p.528

6.6.2.3.3  Solid external walls

Solid walls should be capable of holding moisture arising from rain and snow until it can be released in a dry period without penetrating to the inside of the building or causing damage to the building.

p.529

p.530

6.6.2.3.4  Cavity external walls

The outer leaf of cavity external walls shall be separated from the inner leaf by a drained air space (or in any other way which will prevent precipitation from being carried to the inner leaf).

p.531

p.532

p.533

p.534

6.6.2.3.5  Framed external walls

p.535

It should be noted that the use of combustible materials for cladding framework, or the use of combustible thermal insulation as an over-cladding may be risky in tall buildings, even though the provisions for external surfaces in Figure 6.6.31 may have been satisfied.

Combustible materials should not be placed in or exposed to the cavity, except for:

6.6.2.3.6  Cracking of external walls

Cladding can be designed to protect a building from precipitation (often driven by the wind) either by holding it at the face of the building or by stopping it from penetrating beyond the back of the cladding.

The possibility of severe rain penetrating through cracks in masonry external walls should be taken into account when designing a building.

6.6.2.3.7  Impervious cladding systems for walls

Cladding systems for walls should:

p.536

Note: Whether dry joints are suitable will depend on the design of the joint or the design of the cladding and the severity of the exposure to wind and rain.

p.537

6.6.2.3.8  Joints between walls and doors/window frames

6.6.2.3.9  Interstitial condensation (external walls)

p.538

Specialist advice should be sought when designing swimming pools and other buildings where interstitial condensation in the walls (caused by high internal temperatures and humidity) can cause the generation of high levels of moisture.

6.6.2.3.10  Surface condensation and mould growth (external walls)

External walls shall be designed and constructed so that:

6.2.4  Cavity insulation

Insulating materials which give off formaldehyde fumes (either when used or later in normal use) may be used to insulate the cavity in a cavity wall where there is a continuous barrier which will minimize as far as practicable the passage of fumes to the occupiable parts. A cavity wall may be insulated with urea formaldehyde (UF) foam where:

p.539

6.6.2.5  Resistance to the passage of sound

6.6.2.5.1  Airborne sound

6.6.2.5.2  Performance

p.540

Note:

p.541

In cases like these, it would be best to seek specialist advice before committing yourself.

Figure 6.6.34 illustrates the relevant parts of the building that should be protected from airborne and impact sound in order to satisfy the requirement.

Figure 6.6.35 illustrates the relevant parts of the building that should be protected from airborne and impact sound in order to satisfy Requirement E2a.

p.542

In some circumstances (for example, when a historic building is undergoing a material change of use) it may not be practical to improve the sound insulation to the standards set out in Approved Document E (Resistance to sound), particularly if the special characteristics of such a building need to be recognized. In these circumstances the aim should be to improve sound insulation to an extent that it is practically possible.

Note: BS 7913, The Principles of the Conservation of Historic Buildings, provides guidance on the principles that should be applied when proposing work on historic buildings.

Any building work involving a historic building is a virtual minefield and you would be well advised to seek professional advice well before embarking on any construction or reconstruction work.

p.543

Where pairs of rooms on either side of the separating element are different (e.g. a bedroom and a study, a living room and a bedroom), at least one of the rooms in one of the pairs should be a bedroom and at least one of the rooms in the other pair should be a living room. Where the layout has only one pair of rooms on opposite sides of the entire area of separating wall or floor between two dwelling-houses, flats or rooms for residential purposes, then the number of tests may be reduced.

Some properties (e.g. loft apartments) may be sold before being fitted out with internal walls. However, measurements of sound insulation should still be made between the available spaces. Care should be taken to ensure that fitting does not have an impact on the sound installation.

6.6.2.5.3  Types of wall

As shown in Figure 6.6.36, there are four main types of separating walls that can be used to achieve the required performance standards shown in Table 6.6.11.

Other designs, materials and/or products may also be available and so it is always worth talking to the manufacturers and/or suppliers first.

p.544

The resistance to airborne sound depends mainly on the mass of the wall.

p.545

In new buildings, the walls are grouped into four main types. Within each wall type, the constructions are ranked, as far as possible, with the higher sound insulation given first.

Note: Where any building element functions as a separating element (e.g. a ground floor that is also a separating floor for a basement flat) then the separating element requirements should take precedence.

Table 2.1 in Approved Document E (Resistance to sound) provides guidance on the types of junctions that may occur between each of the four separating wall types.

Note: Recommended cavity widths in separating cavity masonry walls are minimum values.

6.6.2.5.2.1  mass per unit area of walls

The mass per unit area of a wall is expressed in kilograms per square metre (kg/m²) and is equivalent to:

p.546

Mass per unit area of a wall can be calculated by using the following formula:

MB + ρm[Td(L+H-d)+V]kg/m3

where:

Note: The method for calculating mass per unit area is provided in Annex A to Approved Document E (Resistance to sound) of the Regulations, together with some worked examples.

The formula provides the mass per unit area of the block/brick construction without the surface finish.

6.6.2.5.2.2  plasterboard linings on separating and external masonry walls

The guidance below is for wet finishes. For dry finishes, refer to the guidance provided by the manufacturer.

6.6.2.5.2.3  wall ties in separating and external cavity masonry walls

Wall ties for use in masonry cavity walls are either tie type A or B.

p.547

Note: BS 5628–3 limits this tie type and spacing to cavity widths of 50mm to 75mm with a minimum masonry leaf thickness of 90mm). E 2.19

Note: In external cavity masonry walls, tie type B may decrease the airborne sound insulation due to flanking transmission via the external wall leaf compared to tie type A.

p.548

6.6.2.5.2.4  corridor walls and doors

Note: It is highly likely that the amount of sound insulation gained by using a separating wall will be reduced by the presence of a door.

6.6.2.5.2.5  refuse chutes

6.6.2.5.2.6  wall type 1 (solid masonry)

p.549

When using a solid masonry wall, the resistance to airborne sound depends mainly on the mass per unit area of the wall. As shown in Table 6.6.12 there are three different categories of solid masonry walls.

6.6.2.5.2.6.1  Wall type 1 – general requirements

p.550

Note: A cavity separating wall may not be changed into a solid masonry (i.e. type 1) wall by filling in the cavity with mortar and/or concrete.

It is not necessary to stop the cavity wall with a flexible closer if the cavity is fully filled with mineral wool or expanded polystyrene beads.

6.6.2.5.2.6.2  Wall type 1 – Junctions with an external cavity wall with masonry inner leaf

Where the external wall is a cavity wall:

The separating wall should be joined (bonded or tied) to the inner leaf of the external cavity wall by one of the methods shown in AD-E Diagrams 2.6 or 2.7.

p.551

p.552

Note: If there is also a separating floor, then the minimum mass per unit area of 120kg/m² (excluding finish) will always apply, irrespective of the presence or absence of openings.

6.6.2.5.2.6.3  Wall type 1 – Junctions with an external cavity wall with timber-frame inner leaf

p.553

6.6.2.5.2.6.4  Wall type 1 – junctions with internal timber floors

p.554

6.6.2.5.2.6.5  Wall type 1 – junctions with internal concrete floors

Note: For internal floors of concrete beams with infilling blocks, avoid beams built into the separating wall unless the blocks in the floor fill the space between the beams where they penetrate the wall.

6.6.2.5.2.6.6  Wall type 1 – Junctions with concrete ground floors

p.555

6.6.2.5.2.6.7  Junctions with ceiling and roof

Note: A rigid connection between the inner and external wall leaves should be avoided. If a rigid material is used, then it should only be rigidly bonded to one leaf. (For further information, see BRE BR 262).

p.556

6.6.2.5.2.6.8  Other types of wall type 1 junctions

Currently there are no restrictions on internal framed walls meeting a type 1 separating wall nor guidance relating to junctions with an external solid masonry wall so it would be better to seek specialist advice if this is part of your building work.

6.6.2.5.2.6.3  Wall type 2 (cavity masonry)

When using a cavity masonry wall, the resistance to airborne sound depends on the mass per unit area of the leaves and on the degree of isolation achieved. The isolation is affected by connections (e.g. wall ties and foundations) between the wall leaves and by the cavity width. As shown in Table 6.6.13, there are four different categories of cavity masonry wall.

p.557

Note: Types 2.3 and 2.4 are only suitable when a step in elevation and/or a stagger in plan is incorporated at the separating wall.

p.559

6.6.2.5.2.6.3.1  Wall type 2 – general requirements

6.6.2.5.2.6.3.2  Wall type 2 – junctions with an external cavity wall with masonry inner leaf

p.560

p.561

6.6.2.5.2.6.3.3  Wall type 2 Junctions with an external cavity wall with timber-frame inner leaf

Where the external wall is a cavity wall:

Where the inner leaf of an external cavity wall is of framed construction, the framed inner leaf should abut the separating wall and be tied to it with ties at no more than 300mm centres vertically and the wall finish of the inner leaf of the external wall should be:

p.562

6.6.2.5.2.6.3.4  Wall type 2 Junctions with internal timber floors

If the floor joists are to be supported on the separating wall, they should be supported on hangers as opposed to being built in.

6.6.2.5.2.6.3.5  Wall type 2 Junctions with internal concrete floors

Internal concrete floors should generally be built into a type 2 separating wall and carried through to the cavity face of the leaf.

The cavity should not be bridged.

6.6.2.5.2.6.3.6  Wall type 2 Junctions with concrete ground floors

p.563

6.6.2.5.2.6.3.7  Wall type 2 Junctions with ceiling and roof space and wall type 2 – ceiling and roof junction eternal cavity wall at eaves level

p.564

Note: If the roof or loft space is not a habitable room (and there is a ceiling with a minimum mass per unit area of 10kg/m² with sealed joints), then the mass per unit area of the separating wall above the ceiling may be reduced to 150kg/m² – but it should still be a cavity wall.

6.6.2.5.2.6.3.8  Guidance for other wall type 2 junctions

You should seek guidance for junctions with an external solid masonry wall.

When there is a separating floor, the internal masonry walls should also have a mass per unit area of at least 120kg/m² excluding finish.

6.6.2.5.2.6.4  wall type 3 (masonry between independent panels)

p.565

Wall type 3 provides a high resistance to the transmission of both airborne sound and impact sound on the wall. Its resistance to sound depends partly on the type (and mass) of the core and partly on the isolation and mass of the panels. As shown below, there are three different categories of wall type 3, which consist of either a solid or a cavity masonry core wall with independent panels on both sides.

Note: The panels and any frame should not be in contact with the core wall.

6.6.2.5.2.6.4.1  Wall type 3 – general requirements

p.567

6.6.2.5.2.6.4.2  Wall type 3 – Junctions with an external cavity wall with masonry inner leaf

p.568

6.6.2.5.2.6.4.3  Wall type 3 – junctions with internal framed walls

p.569

6.6.2.5.2.6.4.4  Wall type 3 – junctions with internal timber floors

6.6.2.5.2.6.4.5  Wall type 3 – junctions with internal masonry walls

p.570

6.6.2.5.2.6.4.6  Wall type 3 – junctions with internal timber floors

6.6.2.5.2.6.4.7  Wall type 3 – junctions with internal concrete floors

p.571

6.6.2.5.2.6.4.8  Wall type 3 – junctions with timber ground floors

6.6.2.5.2.6.4.9  Wall type 3 – junctions with concrete ground floors

6.6.2.5.2.6.4.10  Wall type 3 – junctions with ceiling and roof space

p.572

p.573

6.6.2.5.2.6.4.11  Wall type 3 – Junctions with internal masonry floors

Internal walls that abut a type 2 separating wall should not be of masonry construction.

As no official guidance is currently available on junctions with an external cavity wall with timber-frame inner leaf and external solid masonry wall junctions, it is best to seek specialist advice.

6.6.2.5.2.6.5  wall type 4 (framed walls with absorbent material)

A wall type 4 consists of a timber frame with a plasterboard lining on the room surface with an absorbent material between the frames. Its resistance to airborne sound depends on:

There is only one wall type 4 described in Approved Document E (Resistance to sound).

6.6.2.5.2.6.5.1 General requirements

p.574

6.6.2.5.2.6.5.2  wall type 4 - Junctions with an external cavity wall with timber-frame inner leaf

p.575

6.6.2.5.2.6.5.3  Wall type 4 - junctions with internal timber floors

p.576

6.6.2.5.2.6.5.4  wall type 4 - junctions with timber ground floors

See also Approved Document C (Site preparation and resistance to moisture) and Approved Document L (Conservation of fuel and power).

6.6.2.5.2.6.5.4  Wall type 4 - junctions with concrete ground floors

6.6.2.5.2.6.5.5  Wall type 4 - junctions with ceiling and roof space

Note: In this case, there need only be one frame in the roof space as long as there is a lining of two layers of plasterboard, each sheet of minimum mass per unit area of 10kg/m², on both sides of the frame.

p.577

See also Approved Document C (Site preparation and resistance to moisture) and Approved Document L (Conservation of fuel and power).

Where there is no official guidance currently available, it is best to seek specialist advice. Particularly in the case of:

There are no restrictions in the following situations:

6.6.2.6  Ventilation

6.6.2.6.1  Ventilation of rooms containing openable windows

6.6.2.7  Drainage and waste disposal

6.6.2.8  Combustion appliances and fuel storage systems

6.6.2.8.1  Permanently open air vents

p.579

6.6.2.8.2  Walls adjacent to hearths

6.6.2.8.3  Thermal expansion

p.580

6.6.2.8.4  Carbon monoxide alarm siting

6.6.2.9  Protection from falling collision and impact

6.6.2.9.1  Guarding

6.6.2.9.2  Critical locations

6.6.2.10  Conservation of fuel and power

6.6.2.10.1  Limiting fabric parameters

If a new conservatory or porch does not meet all these requirements, then it is not exempt and must comply with the relevant energy efficiency requirements of the 2014 revision of Approved Document L (Conservation of fuel and power).

p.581

Removing and not replacing any of the thermal separation between the building and an existing exempt extension, or extending the building’s heating system into the extension, means that the extension ceases to be exempt!

6.6.2.10.2  Upgrading retained thermal elements

Extensions to dwellings should use either newly constructed thermal elements (which meet the requirements for the conservation of fuel and power) or existing (or new) windows, roof windows and rooflights that meet the standards shown in Table 6.6.17.

p.582

6.6.2.10.3  Building fabric

In accordance with the 2014 revision of Approved Document L (Conservation of fuel and power) and Regulation 7, reasonable provision shall be made for the conservation of fuel and power in buildings by limiting heat gains and losses through thermal elements and other parts of the building fabric.

Note: U-values should be calculated using the methods and conventions set out in BR 443 (Conventions for U-value calculations), and should be based on the whole element or unit.

Note: Where a swimming pool is constructed as part of a new building, reasonable provision should be made to limit the heat loss from the pool basin by achieving a U-value no worse than 0.25W/m²K (see BS EN ISO 13370).

6.6.2.10.4  Thermal bridges

To meet this requirement, it is recommended that you use construction joint details that have been calculated following the guidance set out in BRE Report BR 497, Conventions for Calculating Linear Thermal Transmittance and Temperature Factors.

6.6.2.10.5  Party walls and other thermal bypasses

Note: Where outside air flows into the party wall cavity, a cold zone is created which causes heat loss through the wall sections on either side. The extent of air flow and heat changes depends on external conditions such as wind and temperature, and also on the effect of warmed air rising in the cavity and being replaced by cooler air drawn in from outside. The air movements involved can be significant and, if no steps are taken to restrict flows, the resulting heat loss can be large.

p.583

Fully filling the cavity may affect sound transmission through party walls. Developers who plan to fill a party wall cavity must satisfy the BCB that the requirements of Approved Document E (Resistance to sound) will be satisfied, either by adopting a full-fill detail accredited under the Robust Details scheme or through specific site testing.

When calculating the dwelling CO₂ emission rate (DER) and Dwelling Fabric Energy Efficiency (DFEE) rate for a dwelling, a party wall U-value for the type of construction adopted, as set out in Table 6.6.18, should be applied.

The party wall is a particular case of the more general thermal bypass problem that occurs if the air barrier and the insulation layer are not contiguous and the cavity between them is subject to air movement. To avoid the consequent reduction in thermal performance, either the insulation layer should be contiguous with the air barrier at all points in the building envelope, or the space between the air barrier and insulation layer should be filled with solid material, such as in a masonry wall.

p.584

6.6.2.11  Access to and use of dwellings

Note: The loading for strengthened walls is considered suitable for many types of adaptations but additional localised strengthening may be required if adaptations are fitted that impose high point loads.

Remember M4(2) and M4(3) (Access to and use of buildings) are voluntary requirements and only apply in certain circumstances.

6.6.2.12  Electrical safety

p.585

6.6.2.13  Security – dwellings

Note: Approved Document Q (Security in dwellings) came into effect on 1 October 2015 for use in England. It does not apply to work started before 1 October 2015, or work subject to a building notice, full plans application or initial notice submitted before that date provided the work was started on site before 1 October 2016.

p.586

6.6.2.14  Physical infrastructure for high-speed electronic communications networks

p.587

Note: Approved Document R (High-speed electronic communications networks) took effect on 1 January 2017 for use in England. It does not apply to work subject to a building notice, full plans application or initial notice submitted before 1 January 2017.

6.7  Ceilings

6.7.1  Requirements

p.588

p.589

6.7.2  Meeting the requirements

6.7.2.1  Structure

6.7.2.1.1  Ceiling joists

Softwood timber used for roof construction including ceiling joists should be adequately treated to prevent infestation by the house longhorn beetle (Hylotrupes bajulus L.).

p.590

p.591

Note:

6.7.2.1.2  Imposed loads on ceilings

6.7.2.2  Fire protection

6.7.2.2.1  Smoke alarms

There should be a smoke alarm in the circulation space within 7.5m of the door to every habitable room.

Note: This guidance applies to ceilings that are predominantly flat and horizontal.

6.7.2.2.2  Air-circulation systems in houses with a floor more than 4.5m above ground level

To avoid the possibility of smoke or fire spreading into a protected stairway.

p.592

6.7.2.2.3  Cavity barriers

A cavity barrier is termed as ‘any construction which is provided to restrict the movement of smoke or flame within a concealed space’.

p.593

6.7.2.2.4  Suspended ceilings

A suspended, fire-resisting ceiling should meet the requirements given in Table 6.7.1.

Note: For further details, see Approved Document B, Appendix A, Table A3.

6.7.2.2.5  Ceiling linings

The materials used in ceilings can significantly affect the rate of growth and spread of a fire. It is therefore important to consider the material that is used in a circulation space even if it is unlikely to be the material that is first ignited. Therefore, to inhibit the spread of fire within the building, ceiling internal linings shall:

Note: Flame spread over ceiling surfaces is controlled by providing for the lining materials or products to meet given performance levels in tests appropriate to the materials or products involved.

For the purpose of this requirement, the content of ceilings is as described in Table 6.7.2.

p.594

6.7.2.2.6  Classification of linings

In general terms, the surface linings for ceilings should meet the classifications given in Table 6.7.3.

Further guidance on ceiling linings are given in paragraphs 3.2 to 3.14 of Approved Document B V1.

6.7.2.2.7  Heat alarms

Heat detectors and heat alarms should conform to the following requirements.

6.7.2.2.8  Thermoplastic materials

p.595

6.7.2.2.9  Rooflights

Rooflights should meet the relevant classification in Table 6.7.4. They may be constructed of a thermoplastic material if:

6.7.2.2.10  Lighting diffusers

The following guidance applies to lighting diffusers which form part of a ceiling and is not concerned with diffusers of light fittings which are attached to the soffit of, or suspended beneath, a ceiling (see Figure 6.7.4).

p.596

p.597

6.7.2.2.11  Suspended or stretched-skin ceilings

p.598

The ceiling of a room may be constructed from panels of a thermoplastic material of the TP(d) flexible classification, provided that it is not part of a fire-resisting ceiling.

6.7.2.2.12  Fire-resisting ceilings

p.599

p.600

6.7.2.3  Resistance to the passage of sound

6.7.2.3.1 Ceiling and roof junctions

Where a type 1 separating wall is used it should be continuous to the underside of the roof.

6.8.2.3.2  Wall type 1 – solid masonry

p.601

6.7.2.3.3  Wall type 2 – cavity masonry

Note: Where a type 2 separating wall is used, it should be continuous to the underside of the roof.

Remember to fix the supporting frame of panels to the ceiling and floor only.

p.602

6.7.2.3.4  Wall type 3 – masonry between independent panels

p.603

Where it is necessary to connect two leaves together, do not use ties of greater cross section than 40mm x 3mm fixed to the studwork at or just below ceiling height.

6.7.2.3.5  Wall type 4 – framed walls with absorbent material

Note: There needs only be one frame in the roof space, provided there is a lining of two layers of plasterboard, each sheet of minimum mass per unit area 10kg/m², on both sides of the frame.

6.7.2.3.6  Junctions with walls

In all cases for the junction between the ceiling and the walls, the ceiling should be taken through the masonry and sealed with tape or caulked with sealant.

6.7.2.3.7  Ceiling and roof junctions

Where a type 1 separating wall is used it should be continuous to the underside of the roof.

6.7.2.3.8  Ceiling treatment

Each floor type requires one of the ceiling treatments described in this section. The description of each floor type contains a suffix A, B or C and that refers to the ceiling treatment used.

p.604

p.605

Note: Use of a better performing ceiling than that described in the guidance should improve the sound insulation of the floor provided there is no significant flanking transmission.

6.7.2.3.8.1  ceiling treatment A

This is an independent ceiling with absorbent material.

Remember to seal the perimeter of the independent ceiling with tape or sealant and do not create a rigid or direct connection between the independent ceiling and the floor base.

p.606

6.7.2.3.8.2  ceiling treatment B

This is plasterboard on proprietary resilient bars with absorbent material.

6.7.2.3.8.3  ceiling treatment C

This is plasterboard on timber battens or proprietary resilient channels with absorbent material.

p.607

Electrical cables give off heat when in use and special precautions may be required when they are covered by thermally insulating materials.

6.7.2.3.9  Interaction with floors

6.7.2.3.10  Work on existing buildings

p.608

p.609

Do not create a rigid or direct connection between the independent ceiling and the floor base

p.610

6.7.2.3.11  Stairs

6.7.2.4  Ventilation

F1 does not apply to a building or space within a building:

6.7.2.4.1  Interaction of mechanical extract ventilation and open-flued combustion appliances

p.611

p.612

p.613

6.7.2.5  Conservation of fuel and power

6.7.2.6  Access to and use of dwellings – Category 3 – Wheelchair user dwellings M4(3)

Note: Requirements M3.35 and 3.36 are optional requirements for wheelchair user dwellings.

p.614

p.615

6.7.2.7  Electrical safety

p.616

6.8  Roofs

This section also includes information on the composition and placement of rooflights.

The roof of a brick-built house is normally an aitched (sloping) roof comprising rafters fixed to a ridge board, braced by purlins, struts and ties and secured to wall-plates bedded on top of the walls. They are then usually clad with slates or tiles to keep the rain out.

Timber-framed houses usually have trussed roofs – prefabricated triangulated frames that combine the rafters and ceiling joists – which are lifted into place and supported by the rails. The trusses are joined together with horizontal and diagonal ties. A ridge board is not fitted, nor are purlins required. Roofing-felt battens and tiling are applied in the usual way.

Note: Guidance on the sizing of timber floors and roofs for traditional house construction (known as the Timber Tables) are published by TRADA.

p.617

6.8.1  Requirements

p.618

p.619

p.620

6.8.2  Meeting the requirement

6.8.2.1  Structure

Note: Unless they serve the function of a floor (i.e. a roof terrace), roofs are not treated as elements of structure.

6.8.2.1.1  General

Roofs shall be constructed so that they do both of the following:

Note: A traditional cut timber roof (such as one using rafters, purlins and ceiling joists) generally has sufficient built-in resistance to instability and wind forces (e.g. from hipped ends, tiling battens, rigid sarking, etc.). However, the need for diagonal rafter bracing equivalent to that recommended in BS EN 1995–1-1 with its UK National Annex should be considered, especially for single-hipped and non-hipped roofs of greater than 40° pitch to detached houses.

6.8.2.1.2  Imposed loads

Imposed loads on roofs are not permanent and can be variable.

p.621

6.8.2.1.3  Lateral support

Lateral support should be provided to help prevent sideways movement.

p.622

Vertical strapping (at least 1m in length) is required in gable wall unless the roof complies with all of the following:

Gable walls should be strapped to roofs as shown in Figure 6.8.3 (a) and (b) by tension straps.

Walls shall be tied to the roof structure vertically and horizontally and have a horizontal lateral restraint at roof level.

6.8.2.1.4  Timber

Softwood timber used for roof construction or fixed in the roof space (including ceiling joists within the void spaces of the roof), should be adequately treated to prevent infestation by the house longhorn beetle (Hylotrupes bajulus L.).

p.623

p.624

p.625

Note:

6.8.2.1.5  Building height

6.8.2.1.6  Openings

Where an opening in a roof for a stairway adjoins a supported wall and interrupts the continuity of lateral support:

6.8.2.1.7  Proportions for masonry chimneys above the roof surface

p.626

6.8.2.1.8  Further guidance

p.627

6.8.2.1.9  Roof covering

Re-covering of roofs is commonly undertaken to extend the useful life of buildings; however, it should be remembered that roof structures may be required to carry underdrawing or insulation at a later date.

Note: Transparent or translucent covering materials for roofs are not accessible except for normal maintenance and repair and are, therefore, excluded from the requirement to carry the concentrated imposed load upon roofs if they are not fragile or are otherwise suitably protected against collapse.

Note: To extend the useful life of a building, it is common for roofs to be re-covered. However, before work commences a check should be made to ensure that the existing roof structure is able to sustain any significant roof loading, and appropriate strengthening work or replacement of roofing members should be undertaken.

p.628

‘A significant change in roof loading’ is when the loading upon the roof is increased by more than 15 percent. This is classified as a material alteration.

6.8.2.1.10  Pitched roofs covered with slates or tiles

Although Table 6.8.1 does not include guidance for pitched roofs covered with bitumen felt, it should be noted that there is a wide range of materials on the market, and information on specific products is readily available from manufacturers.

6.8.2.1.11  Flat roofs covered with bitumen felt

A flat roof consisting of bitumen felt is (irrespective of the felt specification) deemed to be of designation AA if the felt is laid on a deck constructed of 6mm plywood, 12.5mm wood chipboard, 16mm (finished) plain-edged timber boarding, compressed straw slab, screeded wood-wool slab, profiled fibre-reinforced cement or steel deck (single or double skin) with or without fibre insulating board overlay, profiled aluminium deck (single or double skin) with or without fibre insulating board overlay, or concrete or clay-pot slab (in situ or precast), and has a surface finish of:

p.629

6.8.2.1.12  Pitched or flat roofs covered with fully supported material

Note: Lead sheet supported by timber joists and plain-edged boarding should be regarded as having a ‘BA’ designation.

6.8.2.2  Fire safety

6.8.2.2.1  Emergency egress windows and external doors

p.630

Roof coverings are classed in accordance with the way they may be penetrated by fire and how flames spread. The codes are A–D in each category

Note: Separation distances (i.e. the minimum distance from the roof, or part of the roof, to the relevant or notional boundary) shall be in accordance with Approved Document B, Volume 1, Table 5 according to the type of roof covering and the size and use of the building.

p.631

Thatched roofs can sometimes be vulnerable to spontaneous combustion caused by heat transferred from flues building up in thick layers of thatch in contact with the chimney.

6.8.2.2.2  Rooflights

Note: Thermoplastic materials may be used in windows, rooflights and lighting diffusers in suspended ceilings.

p.632

6.8.2.2.3  Need for cavity barriers

A cavity barrier is any construction which is provided to restrict the movement of smoke or flame within a concealed space.

6.8.2.2.4  Compartmentation

To prevent the spread of fire within a building, whenever possible the building should be subdivided into compartments separated from one another by walls and/or floors of fire-resisting construction.

p.633

6.8.2.2.5  Concealed spaces (cavities)

Concealed spaces or cavities in the construction of roofs will provide an easy route for smoke and flame to spread, which, because it is concealed, will present a greater danger than would a more obvious weakness in the fabric of the building. For this reason:

p.634

Cavity barriers need not be provided between double-skinned corrugated or profiled insulated roof sheeting if the sheeting is a material of limited combustibility.

6.8.2.3  Site preparation and resistance to moisture

Roofs are exposed to moisture in three ways:

Note: There are particular issues when working in historic buildings to ensure that moisture ingress to the roof structure is limited and the roof can breathe. Where it is not possible to provide dedicated ventilation to pitched roofs, it is important to seal existing service penetrations in the ceiling and to provide draught proofing to any loft hatches. Any new loft insulation should be kept sufficiently clear of the eaves so that any adventitious ventilation is not reduced.

p.635

6.8.2.3.1  Precipitation

Roofs have the following functions.

6.8.2.3.2  Resistance to moisture from the outside

Roofs should be designed to protect the building from precipitation either by holding the precipitation at the face of the roof or by stopping it from penetrating beyond the back of the roofing system.

p.636

6.8.2.3.3  Resistance to damage from interstitial condensation

Roofs shall be designed and constructed in accordance with Clause 8.4 of BS 5250 and BS EN ISO 13788.

6.8.2.3.4  Resistance surface condensation and mould growth

Roofs shall be designed and constructed so that the thermal transmittance (U-value) does not exceed 0.35W/m²K at any point.

6.8.2.4  Resistance to the passage of sound

In order for the construction to be fully effective in the resistance to the passage of sound, care should be taken to correctly detail the junctions between the separating wall and the roof.

p.637

6.8.2.4.1  Wall type 1 – solid masonry

Note:

p.638

6.8.2.4.2  Wall type 2 – cavity masonry

Note: Where a type 2 separating wall is used, it should be continuous to the underside of the roof.

Note:

p.639

If the roof or loft space is not a habitable room (and there is a ceiling with a minimum mass per unit area of 10kg/m² with sealed joints), the mass per unit area of the separating wall above the ceiling may be reduced to 150kg/m² – but it should still be a cavity wall.

6.8.2.4.3  Wall type 3 – masonry between independent panels

p.640

For wall type 3.3 (cavity masonry core):

6.8.2.4.4  Wall type 4 – framed walls with absorbent material

p.641

Note: There need only be one frame in the roof space provided there is a lining of two layers of plasterboard, each sheet of minimum mass per unit area 10kg/m², on both sides of the frame.

6.8.2.4.5  Ceiling and roof junctions

Where a type 1 separating wall is used, it should be continuous to the underside of the roof.

6.8.2.5  Ventilation

6.8.2.5.1  Roof with a pitch of 15° or more

Pitched roof spaces should have ventilation openings as shown in Figures 6.8.11 and 6.8.12. There should be ventilation openings at least 10mm wide at eaves level to promote cross-ventilation. A pitched roof that has a single slope and abuts a wall should have ventilation openings at eaves level at least 10mm wide and at high level (i.e. at the junction of the roof and the wall) at least 5mm wide. Pitched roofs where the insulation follows the pitch of the roof need ventilation at the ridge at least 5mm wide.

p.642

6.8.2.5.2  Roof with a pitch of less than 15°

Roof spaces should have ventilation openings at least 25mm wide (Figure 6.8.13) in two opposite sides to promote cross-ventilation. The void should have a free air space of at least 50mm between the roof deck and the insulation. Where the edges of the roof abut a wall or other obstruction in such a way that free air paths cannot be formed to promote cross-ventilation or the movement of air outside any ventilation openings would be restricted, an alternative form of roof construction should be adopted.

p.643

Roofs with a span exceeding 10m may require more ventilation, totalling 0.6 percent of the roof area.

Ventilation openings may be continuous or distributed along the full length and may be fitted with a screen, fascia, baffle, etc. Where necessary (i.e. for the purposes of health and safety), ventilation to small roofs such as those over porches and bay windows should always be provided and a roof that has a pitch of 70° or more shall be insulated as though it were a wall.

If the ceiling of a room follows the pitch of the roof, ventilation should be provided as if it were a flat roof.

6.8.2.5.3  Passive Stack Ventilation

In roof spaces, Passive Stack Ventilation (PSV) should follow the guidance below.

p.644

Note: Placing the outlet terminal at the ridge of the roof is the preferred option, as it is not prone to wind gusts and/or certain wind directions.

6.8.2.6  Sanitation, hot water safety and water efficiency

6.8.2.6.1  Termination of discharge pipe

As the discharge would consist of high temperature water and steam, asphalt, roofing felt and non-metallic rainwater goods may be damaged by such discharges.

p.645

6.8.2.7  Drainage and waste disposal

6.8.2.7.1  Rainfall protection

p.646

6.8.2.8  Combustion appliances

6.8.2.8.1  Factory-made chimneys

p.647

6.8.2.8.2  Tests and examinations

6.8.2.9  Protection from falling, collision and impact

6.8.2.9.1  Siting of pedestrian guarding

p.648

6.8.2.9.2  Siting of vehicle barriers

6.8.2.10  Conservation of fuel and power

The main changes made by the 2016 amendments include the withdrawal of Regulations 29 to 33 of the Building Regulations 2010 and their replacement with Regulation 7A of the Energy Performance of Buildings (England and Wales) Regulations 2012, as well as changes in the wording of Regulations 24, 25, 26, 26A, 27 and 27A of the Building Regulations 2010.

Note: Appendix B to this book (available at www.routledge.com/9781138285163) provides further information concerning the requirements for the conservation of fuel and power.

6.8.2.10.1  Limiting fabric standards

Note: The Building Control Body (BCB) will pay particular attention if the roof U-value is claimed to be greater than 0.13W/m²K.

6.8.2.10.2  Party walls

p.649

6.8.2.10.3  Historic and traditional buildings

When undertaking work on any type of historic or traditional type of building, the aim should always be to improve energy efficiency as far as is reasonably practicable, without prejudicing the character of the host building or increasing the risk of long-term deterioration of the building fabric or fittings.

Building Inspectors normally require the use of sympathetic treatment when restoring the historic character of a building that has been subject to previous inappropriate alteration (e.g. when replacing a roof or a rooflight).

6.8.2.10.4  Non-notifiable work

If you voluntarily install thermal insulation in a roof space or loft space and this is the only work carried out and the work is not carried out to comply with any requirement in the Building Regulations, then it classes as non-notifiable work.

6.8.2.10.5  Extensions

Extensions to dwellings should either use newly constructed thermal elements or make use of existing (or new) roof windows and rooflights, provided that they meet the requirements for the conservation of fuel and power.

Note: Reductions in thermal performance can occur where the air barrier and the insulation layer are not contiguous and the cavity between them is subject to air movement. To avoid this problem, either:

p.650

6.8.2.10.6  Thermal bridges

A suitable approach to showing the requirement has been achieved would be to adopt Accredited Construction, details of which are on www.gov.uk.

6.8.2.11  Electrical safety

Part P applies to electrical installations that are outside the dwelling – for example photovoltaic panels on roofs – as well as to electrical installations within a roof space.

6.8.2.12  Security

Any easily accessible windows (including easily accessible rooflights) fitted in new dwellings should be secure windows (i.e. they should be made to a design that has been shown by test to meet the security requirements of British Standards publication PAS 24). An easily accessible window is one which is within 2m vertically of a flat or sloping roof (with a pitch of less than 30°) that is within 3.5m of ground level.

p.651

6.9  Chimneys and fireplaces

6.9.1  Requirements

p.652

Note: For the purpose of the performance of wall linings, a wall includes fireplace surrounds, mantle shelves and also chimneys if they are attached to the building.

p.653

6.9.2  Meeting the requirements

In accordance with the Clean Air Act 1993, it is an offence for dark smoke to be emitted from a chimney of any building. This prohibition, however, does not apply to emissions that are solely due to the use of unsuitable fuel and:

A person found guilty of an offence under this section is liable, on summary conviction, to a fine in accordance with the ‘standard scale’ contained in the Criminal Justice Act (at the time of publication ,the maximum fine for such offences was £5000).

p.654

6.9.2.1  Structure

6.9.2.1.1  End restraint

6.9.2.1.2  Masonry chimneys

p.655

p.656

6.9.2.2  Fire safety

Proprietary fire-stopping and sealing systems are available and may be used, as they have been shown by test to maintain the fire resistance of an element.

6.9.2.3  Combustion appliances and fuel storage systems

6.9.2.3.1  Construction

p.657

p.658

A flue liner is the wall of the chimney that is in contact with the products of combustion (see Figure 6.9.4), such as a concrete flue liner, the inner liner of a factory-made chimney system or a flexible liner fitted into an existing chimney.

Down-draughts that could interfere with the combustion performance of an open-flued appliance shall be minimized. This can be achieved by using a factory-made draught stabilizer (see Figure 6.9.5) to prevent excessive variations in the draught.

A fireplace recess is a structural opening (sometimes called a builder’s opening) formed in a wall or in a chimney breast, from which a chimney leads and which has a hearth at its base.

p.659

Simple structural openings (Figure 6.9.6(a)) are suitable for closed appliances such as stoves, cookers or boilers, but gathers (Figure 6.9.6(b)) are necessary for accommodating open fires. Fireplace recesses are often lined with firebacks to accommodate inset open fires (Figure 6.9.6(c)). Lining components and decorative treatments fitted around openings reduce the opening area. It is the finished fireplace opening area which determines the size of flue required for an open fire in such a recess.

Flueblock chimney systems consist of a set of factory-made components, made from precast concrete, clay or other masonry units, which are designed for assembly on site to provide a complete chimney that has the appropriate performance for the intended appliance. There are two types of common systems, one being solely for use with gas-burning appliances and the other, often called a chimney block system, being primarily designed for solid fuel-burning appliances.

p.660

Note: Chimneys and flues should also provide satisfactory control of water condensation.

In the gas industry, the chimney for a gas appliance is commonly called the flue.

p.661

6.9.2.3.2  Open fire with a throat and gather

A throat is a contracted part of the flue between a fireplace recess and its chimney (see Figure 6.9.4). Throats are usually formed from prefabricated components.

Permanently open air vents should have a total free area of at least 50 percent of the throat opening area (see Figure 6.9.7).

p.662

6.9.2.3.3  Open fire with no throat (e.g. a fire under a canopy)

Permanently open air vents should have a total free area of at least 50 percent of the cross-sectional area of the flue (see Figure 6.9.8).

6.9.2.3.4  Appliances burning solid fuel (with a rated output up to 50kW)

6.9.2.3.5  Other appliances (such as a stove, cooker or boiler)

Stoves, cookers or boilers should have permanently open air vent(s).

6.9.2.3.6  Carbon monoxide alarms

Note: Carbon monoxide (CO) is a colourless, odourless and tasteless gas that is slightly less dense than air. It is toxic to humans and animals when encountered in higher concentrations, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal biological functions. In the atmosphere it is spatially variable and short-lived, having a role in the formation of ground level ozone. Carbon dioxide is normally expelled through the lungs, but if there is too much carbon dioxide in the blood stream then it can cause hypercapnia, which will trigger a reflex which increases breathing and access to oxygen, such as arousal and turning the head during sleep. A failure of this reflex can be fatal, as in sudden infant death syndrome.

Under current Building Regulations, in England and Wales it is now a mandatory requirement to fit carbon monoxide alarms where new or replacement fixed solid fuel appliances are installed in a home.

In Northern Ireland, it a legal requirement to fit CO alarms in all homes where a new or replacement appliance, not used solely for cooking, is installed.

6.9.2.3.7  Masonry chimneys (change of use)

6.9.2.3.8  Reuse of existing flues

Where it is proposed to bring a flue in an existing chimney back into use or to reuse a flue with a different type or rating of appliance, the flue and the chimney should be checked and, if necessary, altered to ensure that they satisfy the requirements for the proposed use.

If a chimney has been relined in the past using a metal lining system and the appliance is being replaced, the metal liner should also be replaced unless the metal liner can be proven to be recently installed and can be seen to be in good condition.

p.663

6.9.2.3.9  Flueblock chimneys

A flueblock chimney system is a factory-made set of components that are manufactured from precast concrete, clay or other masonry units and assembled on site to provide a complete chimney.

There are two types – one for gas-burning appliances and the other (often called a chimney block system) for solid fuel-burning appliances.

6.9.2.3.10  Masonry and flueblock chimneys

Figure 6.9.11 shows a method of meeting this requirement so that combustible material is at least:

p.664

6.9.2.3.11  Factory-made metal chimneys

Casing the chimney in non-combustible material is recommended.

6.9.2.3.12  Debris collection space

6.9.2.3.13  Flues

Approved Document J provides guidance on how to meet the requirements in terms of constructing a flue or chimney, where each flue serves one appliance only.

p.665

Each solid fuel appliance should have its own flue.

6.9.2.3.14  Condensates in flues

6.9.2.3.15  Flue systems

p.666

6.9.2.3.15.1  flues in chimneys

p.667

6.9.2.3.15.2  height of flues

6.9.2.3.15.3  size of flues

p.668

6.9.2.3.15.4  flue outlets

In areas where nests of squirrels or jackdaws are likely, the fitting of a protective cage designed for solid fuel use and having a mesh size between 6 and 25mm is advisable.

p.669

6.9.2.3.15.5  flues discharging at low level near boundaries

p.670

6.9.2.3.15.6  flue outlet clearances – thatched or shingled roof

p.671

p.672

p.673

6.9.2.3.15.7  thatched roofs

Thatched roofs can sometimes be vulnerable to spontaneous combustion caused by heat being transferred from flues and building up in thick layers of thatch that are in contact with the chimney. To reduce the risk, it is recommended that rigid twin-walled insulated metal flue liners are used within a ventilated (top and bottom) masonry chimney void, provided they are adequately supported and not in direct contact with the masonry.

Non-metallic chimneys and cast in-situ flue liners can also be used, provided the heat transfer to the thatch is assessed in relation to the depth of thatch and risk of spontaneous combustion.

p.674

Spark arrestors are not generally recommended, as they can be difficult to maintain and may increase the risk of flue blockage and flue fires.

p.675

Note: Further information and recommendations are contained in HETAS Information Paper 1/007, Chimneys in Thatched Properties.

6.9.2.3.15.8  connecting flue pipes

Combustible materials in the building fabric should be protected from the heat dissipation from flues so that they are not at risk of catching fire.

p.676

6.9.2.3.15.9  concealed flues

p.677

p.678

p.679

6.9.2.3.15.10  ventilation

Rooms or spaces intended to contain flueless appliances may need permanent ventilation and purge ventilation (e.g. openable windows) or adjustable ventilation and rapid ventilation.

6.9.2.3.15.11  reuse of existing flues

p.680

Oversize flues can be unsafe. A flue may, however, be lined to reduce the flue area to suit the intended appliance.

6.9.2.3.15.12  repair of flues

If the installation and maintenance of a fireplace and/or chimney are deemed as being a material change of use, it is a mandatory requirement that the building is brought up to the standards required by Approved Documents J1 to J3.

p.681

If renovation, refurbishment or repair amounts to or involves the provision of a new or replacement flue liner, it is considered ‘building work’ within the meaning of Regulation 3 of the Building Regulations and must, therefore, not be undertaken without prior notification to the Local Authority. Examples of work that would need to be notified include:

Note: If you are in any doubt about this requirement, you should consult the Building Control Department of your Local Authority or an Approved Inspector.

6.9.2.3.15.13  relining flues

Flues should be swept to remove deposits before being relined.

p.682

In certain circumstances, relining is considered ‘building work’ within the meaning of Regulation 3 of the Building Regulations and must, therefore, not be undertaken without prior notification to the Local Authority. If you are in doubt you should consult the Building Control department of your Local Authority or an Approved Inspector.

p.683

6.9.2.3.16  Fireplaces

Examples of Length (L) and Height (H) for large and unusual fireplace openings are shown in Figure 6.9.18.

6.9.2.3.1.6.1  general

p.684

Note: Lining components and decorative treatments fitted around openings reduce the opening area. It is the finished fireplace opening area that determines the size of flue required for an open fire in such a recess.

Simple recesses are suitable for closed appliances such as room heaters, stoves, cookers or boilers (but are not suitable for an open fire without a canopy!) and can be used for accommodating open fires and free-standing fire baskets. Fireplace recesses are often lined with firebacks to accommodate inset open fires.

p.685

6.9.2.3.1.6.2  fireplace recesses

p.686

p.687

6.9.2.3.1.6.3  fireplace lining components

p.688

p.689

6.9.2.3 1.6.4  construction of fireplace gathers

To minimize resistance to the proper working of flues, tapered gathers should be provided in fireplaces for open fires or corbelling of masonry, as shown in Figure 6.9.20.

p.690

Alternatively, a suitable canopy (as shown in Figure 6.9.21) or a prefabricated appliance chamber incorporating a gather may be used.

p.691

This can be achieved by using prefabricated gather components built into a fireplace recess, as shown in 6.9.22.

p.692

p.693

6.9.2.3.17  Hearths

A hearth is a base intended to safely isolate a combustion appliance from people, combustible parts of the building fabric and soft furnishings. (see Figure 6.9.23).

p.694

6.9.2.3.17.1  Construction of hearths

p.695

p.696

Note: The edges of this surface should be marked (e.g. by a change in level) to provide a warning to the building occupants and to discourage combustible floor finishes such as a carpet from being laid too close to the appliance.

Some ways of making these provisions are shown in Fig 6.9.27.

p.697

6.9.2.3.17.2  walls adjacent to hearths

Note: There is no requirement for protection of the wall where X is more than 150mm

p.698

6.9.2.3.18  Dry lining around fireplace openings

p.699

6.9.2.3.19  Provision of information

On completion of work:

p.700

Note: Guidance on testing is given at Appendix E to Approved Document J:2010.

See Appendix A to Approved Document J:2010 for detailed checklists for checking and testing of hearths, fireplaces, flues and chimneys.

p.701

6.9.2.3.19.1  Notice plates for hearths and flues

Notice plates should be securely fixed either next to the:

p.702

6.9.2.3.20  Maintenance

6.9.2.3.20.1  access to combustion appliances for maintenance

p.703

6.9.2.3.20.2  gas-burning devices

The Gas Safety (Installation and Use) Regulations require that:

Important elements of the regulations include the following.

p.704

Note: Outlets from flues should be situated externally so as to allow the products of combustion to dispel and, if a balanced flue, the intake of air (Figure 6.9.29).

p.705

p.706

6.9.2.3.21  Gas fires (other than flueless gas fires)

A flueless appliance is designed to be used without connection to a flue. Its products of combustion mix with the surrounding room air and are eventually transported to the outside as stale air leaves the room (see Figure 6.9.30).

Gas-fired appliances should only be located where accidental contact is unlikely and where they can be surrounded by a non-combustible surface which provides adequate separation from combustible materials.

p.707

p.708

6.9.2.3.22  Back boilers

p.709

6.9.2.3.23  Kerosene and gas-oil burning appliances

Kerosene (class C2) and gas-oil (class D) appliances have the following, additional, requirements.

Note: Figure 6.9.33 (and Table 6.9.7) indicates typical positioning to meet this requirement.

p.710

Note:

p.712

6.9.2.3.24  Relining chimney flues (for oil appliances)

In some circumstances, lining or relining flues could be considered building work, in which case the works must be brought up to the standards required by Approved Documents J2 to J4.

6.9.2.3.25  Hearths for oil appliances

6.9.2.4  Conservation of fuel and power

6.9.2.4.1  Secondary heating

p.713

6.10  Stairs

6.10.1  Requirements

p.714

6.10.2  Meeting the requirements

6.10.2.1  Structure

6.10.2.1.1  Interruption of Lateral support

6.10.2.1.2  Wall cladding on escape routes

6.10.2.2  Fire safety

For a typical one or two-storey dwelling, the requirement is limited to the provision of smoke alarms and to the provision of openable windows for emergency exit (Approved Document B Volume 1 B1.i). As the upper surfaces of floors and stairs are not significantly involved in a fire until it is well developed, they do not play an important part in fire spread in the early stages of a fire.

p.715

6.10.2.2.1  Means of escape

The basic principles for the design of means of escape are that there should be alternative way for people to flee from most situations.

p.716

6.10.2.2.2  Unprotected and protected escape routes

The unprotected part of an escape route is that part which a person has to traverse before reaching either the safety of a final exit or the comparative safety of a protected escape route, i.e. a protected corridor or protected stairway.

Even with protected horizontal escape routes, the distance to a final exit or protected stairway needs to be limited because the structure does not give protection indefinitely. Protected stairways are designed to provide virtually ‘fire sterile’ areas which lead to places of safety outside the building. Once inside a protected stairway, a person can be considered to be safe from immediate danger from flame and smoke. They can then proceed to a place of safety at their own pace.

p.717

6.10.2.2.3  Positioning of smoke and heat alarms

p.718

6.10.2.2.4  Galleries

6.11.2.2.5  Cavity barriers

6.10.2.2.6  Air-circulation systems in houses with a floor more than 4.5m above ground level

Precautions are required to avoid the possibility of an air-circulation system allowing smoke or fire to spread into a protected stairway by ensuring that the following precautions are taken.

6.10.2.2.7 Passenger lifts

6.10.2.2.8  Windows

A single window can be accepted to serve two rooms as long as both rooms have their own access to the stairs. A communicating door between the rooms should also be provided so that it is possible to gain access to the window without passing through the stair enclosure.

Note: If direct escape to a place of safety is impracticable, it should be possible to reach a place of relative safety such as a protected stairway within a reasonable travel distance.

6.10.2.2.9  Escape stairs

6.10.2.2.9.1  external escape stairs

When an external escape stair may be used:

6.10.2.2.9.2  protection of escape stairs

Note: The provisions described in 2.6 and 2.7 need not be followed if the dwelling has more than one internal stairway, which both afford effective alternative means of escape and are physically separated from each other.

A single stairway is at risk of becoming blocked by smoke from a fire.

6.10.2.2.10  Basements

6.10.2.2.11  Loft conversions

6.10.2.3  Resistance to the passage of sound

The common internal parts of buildings which contain flats or rooms for residential purposes shall be designed in such a way that reverberation around these common parts of the building is minimized.

6.10.2.3.1  Stair treatments

A ‘stair treatment’ (shown in Figure 6.10.5) consists of a stair covering an independent ceiling with absorbent material.

The soft covering should be at least 6mm thick, laid over the stair treads and securely fixed (e.g. glued) so it does not become a safety hazard.

If there is a cupboard under all, or part, of the stair:

If there is no cupboard under the stair, an independent ceiling should be constructed below the stair.

E 4.27

Where a staircase performs a separating function, it shall conform to Approved Document B (Fire safety; see Section 6.10.2.1). Stairs that separate a dwelling from another dwelling (or part of the same building) shall comply with the following.

Figure 6.10.7 illustrates the relevant parts of the building that should be protected from airborne and impact sound in order to satisfy Requirement E2’s.

Note:

6.10.2.3 2  Sound insulation testing

The person completing the building work should arrange for sound insulation testing to be carried out (by a test body with appropriate third-party accreditation) in accordance with the procedure described in Annex B of Approved Document E.

Note: Some properties, for example loft apartments, may be sold before being fitted out with internal walls and other fixtures and fittings. In these cases, sound insulation measurements should be made between the available spaces.

If stairs form a separating function they are subject to the same sound insulation requirements as floors. In this case, the resistance to airborne sound depends mainly on:

6.10.2.3.3  Reverberation

Requirement E3 states that domestic buildings shall be designed and constructed so as to restrict the transmission of echoes. The guidance notes provided in Approved Document E cover two methods (Method A and Method B) which can be used to determine the amount of additional absorption to be used in corridors, hallways, stairwells and entrance halls that give access to flats and rooms for residential purposes. Method A is applicable to stairs and requires the following to be observed:

Note: Method B can generally be satisfied by the use of proprietary acoustic ceilings.

6.10.2.3.4  Piped services

Piped services (excluding gas pipes) and ducts that pass through separating floors should be surrounded with sound-absorbent material for their full height and enclosed in a duct above and below the floor.

6.10.2.3.4.1  junctions with floor penetrations (excluding gas pipes)

6.10.2.3.4.2  junctions with floor penetrations (including gas pipes)

Note: In the Gas Safety Regulations, there are requirements for ventilation of ducts at each floor where they contain gas pipes. Gas pipes may be contained in a separate ventilated duct or they can remain inducted and if a gas service is installed it shall comply with the Gas Safety (Installation and Use) Regulations 1998, SI 1998 No. 2451.

6.10.2.4  Protection from falling, collision and impact

In a dwelling, the maximum pitch for a private stair is 42°. The normal relationship between the dimensions of the rise and going is twice the rise plus the going (2R + G) equals between 550mm and 700mm. Any external tapered steps and stairs that are part of the building should have a going on each step of a minimum of 280mm.

For existing buildings the dimensional requirements in Table 6.10.2 should be followed, unless due to dimensional constraints it is not possible. Any alternative proposal should be agreed with the BCB and included in an access strategy.

6.10.2.4.1  Alternating tread stairs

Alternating tread stairs may only be used in a loft conversion.

6.10.2.4.2  Stairs and ladder

6.10.2.4.2.1  steepness of stairs – rise and going

The rise and going should be in accordance with Figure 6.10.10.

6.10.2.4.2.2  Construction of steps

For common access areas in buildings that contain flats:

6.10.2.4.3  Headroom for stairs

For all buildings:

For loft conversions in dwellings:

6.10.2.4.4  Width of flights of stairs

If the flight is more than 2m wide, divide it into flights a minimum of 1000mm wide, as shown in Figure 6.10.14.
In exceptional circumstances, where severely sloping plots are involved (and a stepped change of level within the entrance storey is unavoidable), the minimum stair width within the entrance storey of a dwelling is 900mm. K 1.16

6.10.2.4.5  Length of flight of stairs for all buildings

6.10.2.4.6  Landings for stairs

Note: Also see Approved Document B (Fire Safety) in Section 6.10.2.1.

6.10.2.4.7  Tapered treads

6.10.2.4.8  Spiral and helical stairs

Not to be confused with BS EN ISO 5395–2 which is for Garden equipment. Safety requirements for combustion-engine-powered lawnmowers. Pedestrian-controlled lawnmowers!

6.10.2.4.9  Handrails for stairs

6.10.2.4.10  Guarding of stairs

6.10.2.4.11  Access for maintenance

Where the stairs or ladders will be used to access areas for maintenance, they should comply with the provisions of BS 5395–3 and the Construction (Design and Management) Regulations 2015 as appropriate.

6.10.2.4.12  Fixed ladders

In dwellings, a fixed ladder may be used – with fixed handrails on both sides – only for access in a loft conversion that contains one habitable room.

Retractable ladders may not be used as means of escape.

6.10.2.4.13  Ramps

6.10.2.4.13.1  construction of ramps

Note: If the change in level is less than 300mm, you must provide a ramp instead of a single step.

6.10.2.4.13.2  design of ramps

For all buildings ramps and landings should be designed in accordance with Figure 6.10.21.

Note: For ramps that are likely to be used by children under five years old, the construction of the guarding shall be such that a 100mm sphere cannot pass through any openings in the guarding and children will not easily climb the guarding.

6.10.2.4.13.4  obstruction of ramps

All ramps should be kept clear of all permanent obstructions.

6.10.2.4.13.5  steepness of ramps

6.10.2.4.14  Protection from falling

Guarding should be provided whenever it is considered necessary from the point of view of safety to guard:

6.10.2.4.14.1  design of guarding

Note: Where glazing is used as part the guarding, refer also to Approved Document K5

Note: Typical locations for guarding are shown in Figure 6.10.24. Further guidance on the design of barriers and infill panels can be found in BS 6180.

6.11  Windows

Windows are a controlled fitting and when they are replaced in an existing building the replacement work should comply with the Approved Documents. FENSA enables companies that install replacement windows and doors to self-certify compliance to the Building Regulations for England and Wales under the relevant competent person scheme. Companies supplying or fitting the units should provide appropriate certification documents. The work once completed should not have a worse level of compliance than before commencement of the work.

Any alterations from a flat window to a bay or bow window, may require planning permission and should be referred to the Local Planning Office.

p.719

6.11.1  Requirements

p.720

p.721

Note: Approved Document M4(2) and M4(3) are optional requirement for accessible and adaptable dwellings and wheelchair user dwellings

6.11.2  Meeting the requirements

6.11.2.1  Fire safety

6.11.2.1.1  Building maintenance and the provision of information

6.11.2.1.2  Means of escape

As the height of emergency egress through upper windows becomes increasingly hazardous, it is necessary to protect the internal stairway.

Note: A single window can serve two rooms provided that both rooms have their own access to the stairs. A communicating door between the rooms should also be provided so that it is possible to gain access to the window without passing through the stair enclosure.

6.11.2.1.3  Emergency egress windows and external doors

Windows should be designed such that they will remain in the open position without needing to be held by a person making their escape.

Note:

6.11.2.1.4  Galleries

6.11.2.1.5  Basements

6.11.2.1.6  Replacement windows

The definition of controlled service or fitting includes a replacement window.

Note: Repair work to windows does not fall within the definition of building work.

Approved Document B3 makes provisions for cavity barriers around window openings in some forms of construction. Where windows are replaced it may be necessary to consider if adequate protection is maintained.

6.11.2.1.7  Loft conversions

6.11.2.1.8  Thermoplastic materials

6.11.2.1.9  Cavity barriers

B1 6.5

6.11.2.1.10  Space separation

6.11.2.2  Site preparation and resistance to moisture

6.11.2.2.1  Cracking of external walls

6.11.2.2.2  Joint between doors and windows

•    The joint between walls and window frames should:

Note: In some cases, the width of the cavity due to thermal insulation and the 50mm clearance for drainage may be such that the window frame is not wide enough to completely cover the cavity closer. The reveal may need to be lined with plasterboard, dry lining, a support system or a thermal backing board. Direct plastering of the internal reveal should only be used with a backing of expanded metal lathing or similar.

6.11.2.2.3  External walls (resistance to surface condensation and mould growth)

6.11.2.2.4  Roofs (resistance to damage from interstitial condensation)

Note: It may not always be necessary to provide ventilation to small roofs such as those over porches and bay windows.

6.11.2.3  Resistance to the passage of sound

6.11.2.4  Ventilation

There shall be adequate means of ventilation provided for people in the building.

6.11.2.4.1 Existing buildings

6.11.2.4.2  Ventilation of a habitable room through another room or a conservatory

6.11.2.4.3  Dimensions of windows

Note: Approved Document B includes provisions for the size of escape windows where the requirements differ the larger of the provisions in Approved Document B or F should apply in all cases.

p.722

6.11.2.4.4  Trickle ventilation

p.723

6.11.2.4.5 Purge ventilation

6.11.2.5  Drainage and waste disposal

p.724

6.11.2.6  Combustion appliances and fuel storage systems

6.11.2.6.1  Interaction of mechanical extract ventilation and open-flued combustion appliances

Extract fans lower the pressure in buildings which can cause the spillage of combustion products from open-flued appliances. Tests that show combustion appliances operate safely whether or not fans are running are required.

p.725

6.11.2.6.2  Carbon monoxide alarm location

p.726

6.11.2.6.3  Locations of flue outlets near windows

p.727

6.11.2.7  Protection from falling, collision and impact

6.11.2.7.1  Pedestrian guarding

Provision shall be made to prevent people moving in or about the building from colliding with open windows, skylights or ventilators.

p.728

6.11.2.7.2  Glazing in critical locations

p.729

Note: For the purposes of this recommendation, a ‘small pane’ (see Figure 6.11.8) is an isolated pane or one of a number of panes held in glazing bars, traditional leaded lights or copper lights with the following dimensions:

p.730

p.731

p.732

6.11.2.7  Conservation of fuel and power

Since April 2014 all new homes (i.e. dwellings) need to achieve, or better, a fabric energy efficiency target in addition to the strengthened requirement to deliver 6 percent carbon dioxide savings.

Note: Regulation 25B (Nearly zero-energy requirements for new buildings) will not come into force until 2019 at the earliest and is therefore not covered in this edition.

p.733

6.11.2.8.1  Exemption from energy efficiency requirements

Note: In these Regulations ‘thermal element’ does not include windows, roof windows or rooflights.

When restoring the character of a historic building that has been subject to previous inappropriate alteration (e.g. replacement windows) sympathetic treatment and advice from others could be very be beneficial.

p.734

6.11.2.8.2  Limiting fabric standards

6.11.2.8.3  Solar gain

6.11.2.8.4  Thermal bridges

Alternative approaches for using linear transmittance are not mutually exclusive. For example, a builder could use approved design details for the majority of the junctions, but use a calculated bespoke detail for the window head.

p.735

6.11.2.8.5  Energy performance certificates

Regulation 7A of the Energy Performance of Buildings (England and Wales) Regulations 2012 requires that, when a dwelling is erected, the person carrying out the work must provide an energy performance certificate to the owner of the building as well as a notice to the BCB that a certificate has been given including the reference number under which the certificate has been registered. (See also the Energy Performance of Buildings (England and Wales) Regulations 2012 (SI 2012/3118) at www.legislation.gov.uk and detailed guidance on energy performance certificates at www.gov.uk).

People who are responsible for building work (for example the agent, designer, builder or installer) must ensure that the work complies with all applicable requirements of the Building Regulations. But the building owner may also be responsible for ensuring that work complies with the Building Regulations. If building work does not comply with the Building Regulations, the building owner could well be served with an enforcement notice.

p.736

6.11.2.8.6  Controlled fittings

The application of the term controlled fitting to a window, roof window, or rooflight refers to a whole unit, including the frame. Consequently, replacing the glazing while retaining an existing frame is not providing a controlled fitting, and so such work is not notifiable and does not have to meet the Part L standards, although where practical it would be sensible to do so.

The U-values for roof windows and rooflights given in Approved Document L1B are based on the U-value of a roof window or rooflight in the vertical position. If a particular unit has been assessed in a plane other than the vertical, the standards given in this Approved Document should be modified by making an adjustment that is dependent on the slope.

p.737

6.11.2.8.7  Conservatories and porches

p.738

6.11.2.8.8  Extensions – area of windows

6.11.2.8.9  Consequential improvements

then in addition to the proposed building work (i.e. the principal works), consequential improvements will have to be completed, provided that they are technically, functionally and economically feasible. L1B 2.1

p.739

6.11.2.9  Access to and use of buildings

Approved Document M is all about making sure that when a new dwelling is being designed and built, reasonable provisions for most people (including wheelchair users and ambulant disabled people) have been included allow them to approach and enter the dwelling and to access habitable rooms and sanitary facilities on the entrance storey.

Sections 6.11.2.9.1 to 6.11.2.9.3 are optional requirements relating to windows for Accessible and adaptable dwellings M4(2) and wheelchair-user dwellings.

6.11.2.9.1  Habitable rooms – living, kitchen and eating areas

6.11.2.9.2  Bedrooms

6.11.2.9.3  Services and controls

6.11.2.10  Security – dwellings

Note: Windows satisfying other standards that provide similar or better performance are also acceptable. These standards include:

p.740

6.12  Doors

6.12.1  Requirements

6.12.2  Meeting the requirements

6.12.2.1  Fire safety

6.12.2.1.1  Building maintenance - provision of information

p.741

6.12.2.1.2  Alarms – smoke and heat alarms and detectors

p.742

6.12.2.1.3  Doors in compartment walls

p.743

6.12.2.1.4  Openings in cavity barriers

p.744

6.12.2.1.5  Vehicle access

6.12.2.1.6  Fire resistance

p.745

p.746

All fire doors should be classified in accordance with BS EN 13501–2 and tested in accordance with BS EN 1634–1.

6.12.2.1.7  Fire doors in dwellings

Self-closing fire doors should be positioned so that smoke will not affect access to more than one stairway. The minimum fire resistance for doors in buildings other than dwellings is as given in Table 6.12.2. Glazing in any fire-resisting door should be fire-resisting and fixed shut.

p.747

BS 8214 gives recommendations for the specification, design, construction, installation and maintenance of fire doors constructed with non-metallic door leaves.

p.748

Guidance on timber fire-resisting doorsets may be found in Timber Fire-Resisting Doorsets: Maintaining Performance under the New European Test Standard, published by TRADA.

Note: Unless pressurization techniques which comply with BS EN 12101–6 are used, fire doors should also either:

p.749

Authors’ note: A classification of Sa is used for doors which require restricted smoke leakage at ambient temperatures.

p.750

Note: A room accessed only via an inner room (an inner-inner room) may be acceptable if not more than one door separates the room from an interlinked smoke alarm and none of the access rooms is a kitchen. B 2.8

Note: Detailed guidance on door openings and fire doors is given in Appendix B of Approved Document B

p.751

6.12.2.1.8  Fire-protected stairways

6.12.2.1.9  Basements

Owing to the risk that a single stairway may be blocked by smoke from a fire in the basement or ground storey:

6.12.2.1.10  Loft conversions

p.752

In an ‘open-plan’ arrangement, it may be possible to provide sprinkler protection to the open-plan area, in conjunction with a fire-resisting partition and door, in order to separate the ground floor from the upper storeys. This door should be so arranged to allow the occupants of the loft room to access an escape window at first floor level. Cooking facilities should be separated from the open-plan area with fire-resisting construction.

If it is considered undesirable to replace existing doors (e.g. if they are of historical or architectural merit) it may be possible to retain the doors or upgrade them to an acceptable standard.

6.12.2.1.11  Garages

p.753

•    Except for kitchens, all habitable rooms in the upper storey(s) of a dwelling served by only one stair should have direct access to a protected stairway. B 2.7

Note: A communicating door between rooms should be provided so that it is possible to gain access to the escape window without passing through the stair enclosure and (when fitted) manual call points for fire alarm systems should be adjacent to exit doors.

6.12.2.2  Site preparation and resistance to moisture

6.12.2.2.1  Cladding

6.12.2.2.2  Joints between doors and walls

p.754

6.12.2.2.3  External walls (resistance to surface condensation and mould growth)

6.12.2.3  Resistance to the passage of sound

6.12.2.3.1  Corridor walls and doors

6.12.2.3.2  Stair covering and independent ceiling with absorbent material

p.755

6.12.2.3.3  Lightweight doors

Lightweight doors with poor perimeter sealing provide a lower standard of sound insulation than walls. This will reduce the effective sound insulation of the internal wall. Ways of improving sound insulation include ensuring that there is good perimeter sealing or by using a doorset.

6.12.2.3.4  Tests for soundproofing

Although not specifically required in test reports, it may be useful to have a description of the building including dimensions and position of any doors in external walls.

6.12.2.4  Ventilation

p.756

Note: If a room contains more than one external door (or a combination of at least one external door and at least one openable window), the areas of all the opening parts may be added together to achieve at least 1/20 of the floor area of the room.

6.12.2.5  Sanitation, hot water safety and water efficiency

6.12.2.6  Drainage and waste disposal

6.12.2.7  Combustion appliances and fuel storage systems

6.12.2.7.1  Provisions where there is a risk of oil pollution

p.757

6.12.2.7.2  Air permeability testing

6.12.2.8  Protection from falling, collision and impact

6.12.2.8.1  Doors on landings

A landing may include part of the floor of the building and should be kept clear of permanent obstructions.

6.12.2.8.2  Glazing in critical locations

Impacts with glazing, particularly glazing in doors and door side panels can result in cutting and piercing injuries. For doors and door side panels, the risk is greatest for glazing between floor and shoulder level when near to door handles and push plates, especially when normal building movement causes doors to stick.

p.758

p.759

6.12.2.8.3  Safe breakage

6.12.2.9  Conservation of fuel and power

6.12.2.9.1  Thermal bridges

The building fabric should be constructed so that there are no reasonably avoidable thermal bridges in the insulation layers caused by gaps within the various elements, at the joints between elements, and at the edges of elements, such as those around window and door openings.

p.760

6.12.2.9.2  Historic buildings

Particular issues relating to work in historic buildings which warrant sympathetic treatment. In this case advice from others could be beneficial. Particularly when restoring the historic character of a building that has been subject to previous inappropriate alteration, e.g. replacement doors.

6.12.2.9.3  Conservatories and porches.

6.12.2.9.4  Major renovation

Major renovation means the renovation of a building where more than 25 percent of the surface-area of the building envelope undergoes renovation.

6.12.2.9.5  Energy efficiency

Energy efficiency measures must be provided that limit the heat loss through the doors, etc. by suitable means of insulation.

p.761

6.12.2.6.5.1  CO₂emission rate for the building

Responsibility for achieving compliance with the requirements of Approved Document L for the conservation of fuel and power rests with the main (or sub-) contractor, or a specialist firm directly engaged by a private client.

The person responsible for achieving compliance should either provide a certificate himself or obtain a certificate from the subcontractor that commissioning has been successfully carried out. The certificate should be made available to the client and the BCB.

6.12.2.9.6  Extensions

Effective thermal separation should be provided between the heated area in the existing dwelling (i.e. the walls, doors, and windows between the dwelling and the extension), should be insulated and draught proofed to at least the same extent as in the existing dwelling.

6.12.2.9.6.2  area of windows, roof windows and doors

p.762

6.12.2.9.6.3  whole dwelling calculation method

Note: The data in SAP 2012 Appendix S can be used to estimate the performance of the elements of the existing building where these are unknown.

Removing, and not replacing, any or all of the thermal separation between the dwelling and an existing exempt extension, or extending the dwelling’s heating system into the extension, means the extension ceases to be exempt and should be treated as a conventional extension. If the total floor area of the proposed extension exceeds these limits, the work should be regarded as a new building and the requirements of Approved Documents L2A and L2B should be used.

In addition, doors between the building and an extension should be insulated and weather-stripped to at least the same extent as in the existing building. To meet this requirement, it is recommended that you use construction joint details that have been calculated following the guidance set out in BRE Report BR 497.

p.763

6.12.2.9.7  Material change of use and change of energy status

6.12.2.9.8  Controlled fittings

The application of the term ‘controlled fitting’ to a door refers to the complete doorset (leaf plus frame) and so replacing a door leaf (while retaining the existing frame) is not notifiable and does not have to meet Approved Document L’s requirements – although where practical it would be sensible to do so!

p.764

When working on a controlled service or fitting (i.e. where the service or fitting is subject to the requirements of Approved Documents G, H, J, L or P), and where windows, roof windows, rooflights and/or doors are to be provided:

6.12.2.10  Access to and use of buildings

6.12.2.10.1  External ramps forming part of an approach route

6.12.2.10.2  Communal entrances

p.765

6.12.2.10.3  Circulation areas and internal doorways – door and hall widths

6.12.2.10.4  WC facilities

p.766

6.12.2.10.5  Approach route

6.12.2.10.6  Principal communal entrance

p.767

The following are additional requirements for wheelchair-accessible dwellings:

p.768

6.12.2.11  Electrical safety – dwellings

6.12.2.12  Security – dwellings

Authors’ note: Approved Document Q is a new requirement for England and Wales and came into effect in October 2015.

6.12.2.12.1  General

All easily accessible doorsets (including garage doorsets and communal entrance doorsets) that provide access into a dwelling or into a building containing a dwelling should be secure doorsets in accordance with Approved Document paragraphs 1.2 to 1.4 shown below.

Note: If a garage has no interconnecting doorset that allows access into the dwelling, the doorset need not be a secure doorset. Where access to the dwelling can be gained via an interconnecting doorset from the garage, then either the garage doorset (pedestrian and vehicular) or the interconnecting doorset should be a secure doorset.

6.12.2.12.2  Design of secure doorsets

p.769

Note: In some situations, a door chain or limiter is not appropriate, for example where a warden may need emergency access to residents in sheltered housing. Alternative caller-identification measures, such as electronic audio-visual door entry systems, can be used to identify visitors.

6.12.2.9.3  Installation and fixing of secure doorsets

p.770

6.13  Access routes to, from and within buildings

6.13.1  Requirements

p.771

The guidance provided in the Approved Documents are in relation to the permanent features which form part of the building. There may situations, such as access for maintenance which are used less frequently where the provisions of the Construction (Design and Management) Regulations 2015 are more appropriate.

p.772

6.13.2  Meeting the requirements

p.773

6.13.2.1  Fire safety

The building shall be designed and constructed so as to provide reasonable facilities to assist firefighters in the protection of life and be constructed in a manner to enable fire appliances to gain access to the building.

p.774

6.13.2.1.1  Access for fire appliances and firefighters

Note: It may not always be reasonable to upgrade an existing route across a site to a small building such as a single dwelling. The options in such a case, from doing no work to upgrading certain features of the route, e.g. a sharp bend, should be considered by the BCB in consultation with the fire and rescue service.

p.775

6.13.2.1.2  Means of escape

p.776

p.777

Note: If it is considered undesirable to replace existing doors (e.g. if they are of historical or architectural merit), it may be possible to retain the doors or upgrade them to an acceptable standard.

Where an ‘open-plan’ arrangement exists at ground level, it may be necessary to provide a new partition to enclose the escape route. Alternatively, it may be possible to provide sprinkler protection to the open-plan area, in conjunction with a fire-resisting partition and door, in order to separate the ground floor from the upper storeys. This door should be so arranged to allow the occupants of the loft room to access an escape window at first floor in the event of a fire in the open-plan area. Cooking facilities should be separated from the open-plan area with fire-resisting construction.

A room accessed only via an inner room (i.e. an inner-inner room) may be acceptable, if it complies with the above, provided that not more than one door separates the room from an interlinked smoke alarm and none of the access rooms is a kitchen.

6.13.2.1.3  Lifts

p.778

6.13.2.2  Site preparation and resistance to contaminants and moisture

6.13.2.2.1  Site assessment

Note: There may be a case for a lower remedy level if part of the land associated with the building is accessible to a lesser extent those in and about the building than the main parts of the buildings and their respective gardens.

6.13.2.2.2  Subsoil drains

6.13.2.2.3  Ventilated airspace

6.13.2.2.4  Accessible thresholds

6.13.2.3  Resistance to the passage of sound

6.13.2.3.1  Sets of tests in flats with a separating floor and a separating wall

p.779

6.13.2.3.2  Corridor walls and doors

Additional absorption should to be used in corridors, hallways, stairwells and entrance halls that give access to flats and rooms for residential purposes.

6.13.2.4  Ventilation

6.13.2.4.1  Live-work units

p.780

6.13.2.4.2  New dwellings

6.13.2.4.3  Access for maintenance

Note: Where no special provision is required, the requirement could be satisfied if 600mm space is provided where access is required between plant. 1100mm should be provided where space for routine cleaning is required.

6.13.2.4.4  Ventilation controls

6.13.2.5  Sanitation, hot water safety and water efficiency

6.13.2.5.1  Design and installation of hot water storage systems

6.13.2.5.2  Sanitary conveniences and washing facilities

Note: Attention is also drawn to the requirements for accessible sanitary conveniences and hand-washing facilities of Approved Document M (Access routes to, from and within buildings).

p.781

6.13.2.5.2  Scale of provision and layout in dwellings

Note: In dwellings, a room containing both a sanitary convenience and a basin for hand washing does not need a separation lobby between this room and a kitchen or food preparation area. The layout for a room containing a sanitary convenience only should be such that the room or space containing its associated hand-washing facilities is accessed before entry to a food preparation area, and is separated from that area by a door.

6.13.2.5.3  Discharges to drain

6.13.2.6  Drainage and waste disposal

6.13.2.6.1  Foul water drainage – access for clearing blockages.

p.782

6.13.2.6.2  Septic tanks

This distance may need to be reduced where the depth to the invert of the tank is more than 3m. There should also be a clear route for the hose such that the tank can be emptied and cleaned without hazard to the building occupants and without the contents being taken through a dwelling or place of work.

6.13.2.6.3  Sanitary pipework

p.783

6.13.2.6.4  Cesspools siting

6.13.2.6.5  Greywater and rainwater storage tank

6.13.2.6.6  Special protection – rodent control

6.13.2.6.7  Clearance of blockage

p.784

Note: If you repair, reconstruct or alter a drain you MUST give free access to the Local Authority to inspect the works.

p.785

6.13.2.6.8  Sealing disused drains

Drains or sewers less than 1.5m deep which are in open ground should as far as is practicable be removed. Other pipes should be sealed at both ends and at any point of connection, and grout-filled to ensure that rats cannot gain access.

6.13.2.6.9  Rainwater drainage

6.13.2.6.10  Refuse storage

6.13.2.6.11  Building over sewers

6.13.2.6.12  Maintaining access

p.786

6.13.2.6.13  Solid waste storage

6.13.2.7  Combustion appliances and fuel storage systems

6.13.2.7.1  Metal chimney and flues

p.787

p.788

6.13.2.7.2  Configuration of natural draught flues serving open-flued

Flue systems should offer least resistance to the passage of flue gases by minimizing changes in direction or horizontal length.

Note: A way of doing this would be to limit the number of changes of direction between the combustion appliance outlet and the flue outlet to not more than four (each up to 45°), not more than two of these being between an intended point of access for sweeping and either another point of access for sweeping or the flue outlet. (90° factory-made bends, elbows or T-pieces in fluepipes may be treated as being equal to two 45° bends.)

6.13.2.7.3.  Inspection and cleaning openings in flues

6.13.2.7.4.  Access to combustion appliances for maintenance

6.13.2.7.5  Debris collection space

This can be achieved by providing a space having a volume of not less than 12 litres and a depth of at least 250mm below the point where flue gases discharge into the chimney. The space should be readily accessible for clearance of debris, for example by removal of the appliance.

p.789

6.13.2.7.6  Location and support of cylinders

6.13.2.8  Protection from falling, collision and impact

6.13.2.8.1  Access routes – hazards

p.790

6.13.2.8.2  Access stairs

6.13.2.8.3  Alternating tread stairs in dwellings

6.13.2.8.4  Protection against impact from and trapping by doors

p.791

6.13.2.8.5  Access routes guarding

For common access areas of buildings that contain flats:

6.13.2.8.6  Pedestrian guarding

Guarding should be provided whenever it is considered necessary from the point of view of safety to guard:

Note: Guarding is not required on ramps that are used only for vehicle access or in places such as loading bays where it would obstruct normal use.

6.13.2.8.7  Balcony guarding

If a balcony or flat roof is provided for escape purposes (or whenever it is considered necessary from a safety point of view) guarding should be provided to guard the edges of any part of a floor (including the edge below an opening window) of a gallery or balcony (and any other openings), and any other place to which people have access.

Note: Guarding is not required in places such as loading bays where it would obstruct normal use.

p.792

6.13.2.8.8  Access routes – handrails for stairs

6.13.2.8.9  Access routes – width of ramps

In dwellings and common access areas in buildings that contain flats with ramps that are:

Note: Handrails should give firm suppo rt and allow a firm grip and may form the top of the guarding.

p.793

6.13.2.8.10  Access – vehicles

For all buildings:

Note: Where parts of windows, skylights and ventilators project inside or outside a building on an access route a suitable barrier should be provided.

6.13.2.8.11  Access for maintenance

Where the stairs or ladders will be used to access areas for maintenance they should comply with the provisions of BS 5395–3 and the Construction (Design and Management) Regulations 2015 as appropriate.

6.13.2.8.12  Access for cleaning windows, etc.

Where a person standing on a permanent stable surface cannot safely clean a glazed surface:

p.794

If none of the above alternatives is possible, then scaffolding towers (portable or fixed) will have to be used.

6.13.2.8.13  Access between levels – all buildings

6.13.2.8.14  Means of escape

In dwellings, a fixed ladder may be used – with fixed handrails on both sides – for access in a loft conversion that contains one habitable room.

Retractable ladders may not be used as means of escape.

p.795

6.13.2.9  Access to and use of buildings

Note: In 2016, Approved Document M was updated and now the only compulsory requirement dealing with access for dwellings is contained in Requirement M4(1). Requirements M4(2) Accessible and adaptable dwellings and M4(3) Category 3 Wheelchair user dwellings are optional requirements for dwellings and only apply of the owner of the property desires this to be the case.

6.13.2.9.1  New dwellings

p.796

Requirements for accessibility should be balanced against preserving historic buildings or environments. In achieving an appropriate balance, it would be appropriate to take into account the advice of the Local Authority’s conservation and access officers, English Heritage and the views of local access groups.

6.13.2.9.2  Approach to a dwelling

p.797

p.798

6.13.2.9.3  Entrances

The principal communal entrance door of the building containing the dwelling should comply with all of the following:

For private entrances where a step into the dwelling is unavoidable, the rise is a maximum 150mm and is aligned with the outside face of the door threshold.

6.13.2.9.4  Communal lifts and stairs

p.799

6.13.2.9.5  Communal stairs

6.13.2.9.6  Door and hall widths

p.800

6.13.2.9.7  Private stairs and changes of level within the entrance storey

p.801

6.15.2.9.2  Provision for accessible and wheelchair-adaptable dwellings

The provision of dwellings that are accessible and/or wheelchair adaptable is an optional requirement. The following is a summary of the main areas you should consider if you wish to go down this route.

p.802

6.14  Corridors and passageways

6.14.1  Requirements

p.803

Amendments to Approved Document M came into force in 2015 with a further revision in 2016.

6.14.2  Meeting the requirements

6.14.2.1  Fire safety

6.14.2.1.1  Unprotected and protected escape routes

The unprotected part of an escape route is that part which a person has to traverse before reaching either the safety of a final exit or the comparative safety of a protected escape route, i.e. a protected corridor or protected stairway.

p.804

6.14.2.2  Site preparation and resistance to contaminants and moisture

6.14.2.3  Resistance to the passage of sound

6.14.2.3.1  Sound insulation testing

6.14.2.3.2  Corridor walls

The separating walls described in this section should be used between corridors and rooms in flats, in order to control flanking transmission and to provide the required sound insulation. However, it is likely that the sound insulation will be reduced by the presence of a door.

Sound insulation will be reduced by the presence of a door.

p.805

Note:

6.14.2.3.3  Reverberation in the common internal parts of buildings

When an entrance hall, corridor, hallway or stairwell provides access to flats and rooms used for residential purposes, the following guidance should be used followed for each space.

p.806

Method B is intended only for corridors, hallways and entrance halls as it is not well suited to stairwells.

Note: This method is described in detail in Section 7 of Approved Document E.

6.14.2.4  Protection from falling collision and impact

6.14.2.4.1  Permanent methods to indicate glazing, and alternative methods

p.807

6.14.2.5  Access to and use of buildings

6.14.2.5.1  Door and hall width

In all dwellings to facilitate access into habitable rooms and to a WC in the entrance storey, door and hall widths should comply with Figure 6.14.2 and take note of the following guidance:

p.808

6.14.2.5.2  Approach to the dwelling

For a house (or other dwelling that sits within its own plot), the approach route will often only involve a driveway, or a gate and a path, but for a dwelling within a larger building (typically a block of flats) the approach route will usually involve one or more communal gates, paths, entrances, doors, lobbies, corridors and access decks, as well as communal lifts and stairs.

For an accessible or adaptable dwellings using Approved Document M4(2) doors and corridors should comply with Figure 6.14.3. To facilitate movement into, and between, rooms throughout the dwelling and take note of the following requirements:

p.809

Note: M4(2) is an optional requirement for accessible and adaptable dwellings.

6.14.2.6  Electrical safety

6.14.2.6.1  Scope

p.810

6.15  Sanitary accommodation, bathrooms and showers

6.15.1  Requirements

p.811

p.812

p.813

Amendments to Approved Document M came into force in 2015 with a further revision in 2016.

6.15.2  Meeting the requirements

All buildings (except factories and buildings used as workplaces) shall be provided with sufficient closet (or privy) accommodation according to the intended use of that building and the amount of people using that building. The only exceptions are if the building (in the view of the local authority) has an insufficient water supply and a sewer is not available.

6.15.2.1  Fire safety

6.15.2.1.1  Smoke alarms

6.15.2.1.2  Inner rooms

6.15.2.1.3  Protection of openings for pipes

p.814

6.15.2.2  Site preparation and resistance to moisture

6.15.2.2.1  Spillage

In bathrooms where water may be spilled, any board used as a flooring, irrespective of the storey, should be moisture resistant.

6.15.2.2.2  Roofs - resistance to damage from interstitial condensation

p.815

6.15.2.2.3  Subsoil drainage

6.15.2.3  Resistance to the passage of sound

6.15.2.3.1  Junctions with floor penetrations

Fire-stopping should be flexible and prevent rigid contact between the pipe and floor.

Note: Enclosure can either lined or the duct (or pipe) within the enclosure can be wrapped with 25mm unfaced mineral fibre.

p.816

6.15.2.3.2  Dwellings and flats formed by a material change of use

6.15.2.4  Ventilation

6.15.2.4.1  Minor works

6.15.2.4.2  Performance of ventilation system

p.817

6.15.2.4.3  Control of the ventilation system

Note:

6.15.2.4.4  Noise

Noise generated by ventilation fans may disturb the occupants of the building and so discourage their use. The designer should, therefore, consider minimizing noise by careful design and by specifying a quieter product. To ensure good acoustic conditions, the average A-weighted sound pressure level in noise sensitive rooms, such as bedrooms and living rooms, should not exceed 30dB LAeq,T. In less sensitive rooms, such as kitchens and bathrooms, a higher level would be acceptable, e.g. 35dB LAeq,T.

p.818

Noise from a continuously running mechanical ventilation system on its minimum low rate should not normally exceed these levels and should preferably be lower.

6.15.2.4.5  Extract ventilation

Extract ventilation concerns the removal of air directly from a space or spaces to outside. Extract ventilation may be by natural means such as Passive Stack Ventilation (PSV) or by mechanical means (e.g. by an extract fan).

6.15.2.4.6  Purge ventilation

p.819

Note: Manual boost controls should be provided locally to the spaces being served

6.15.2.5  Sanitation, hot water safety and water efficiency

6.15.2.5.1  Provision of hot water supply

Note: Guidance on the use of in-line blending valves can be found in BRE Information paper IP14/03.

6.15.2.5.2  Bathrooms

6.15.2.5.3  Sanitary conveniences

Sanitary conveniences of an appropriate type for the sex and age of the persons using the building shall be provided in sufficient numbers. Hand-washing facilities shall be provided in, or adjacent to, rooms containing sanitary conveniences.

Guidance on the selection, installation and maintenance of sanitary appliances including composting toilets may be found in BS 6465–3.

p.820

Note:

6.15.2.5.4  Sanitary appliances

The manner in which sanitary appliances and white goods are identified and used in the design calculation shall be provided and installed in the dwelling.

p.821

6.15.2.5.5  Discharge pipes

6.15.2.5.6  Prevention of scalding

We think that this is because most people are right handed and it is to stop people (particularly children and poorly sighted people) inadvertently scalding themselves. To be on the safe side, therefore, it is recommended that, even though the requirement only applies to new buildings, you always ensure the hot water taps are located on the left-hand side of all of your basins and baths.

p.822

6.15.2.5.6  Scale of provision and layout in dwellings

Note: Guidance on the provision of activity space around sanitary appliances is in BS 6465–2.

p.823

6.15.2.5.7  Chemical and composting toilets

p.824

6.15.2.5.8  Discharge to drains

6.15.2.6  Drainage and waste disposal

6.15.2.6.1  Flush volumes

p.825

6.15.2.6.1  Branch discharge pipes

p.826

p.827

p.828

6.15.2.6.3  Ventilation of branch pipes

p.829

p.830

6.15.2.6.4  Discharge stacks

p.831

p.832

6.15.2.6.5  Materials for sanitary pipes fittings and joints

p.833

6.15.2.6.6  Foul drainage

6.15.2.6.7  Pipe gradients and sizes

p.834

6.15.2.6.8  Greywater recovery systems

Note: Further guidance on greywater recovery systems can be found in the Water Regulations Advisory Scheme Leaflet No. 09-02-04, Reclaimed Water Systems. Information about installing, modifying or maintaining reclaimed water systems.

p.835

6.15.2.7  Combustion appliances and fuel storage systems

6.15.2.7.1  Location of outlets from flues

6.15.2.7.2  Appliances fitted in bathrooms

Any appliance installed in a room that is used (or intended to be used) as a bathroom must be of the room-sealed type.

Bathrooms (and for that matter WCs or showers) that are situated less than 4.5m above ground level and whose only escape route is through another room shall be provided with an emergency egress window.

Smoke alarms should not be fixed in bathrooms.

6.15.2.8  Protection from falling, collision and impact

6.15.2.8.1  Alternating tread stairs

6.15.2.9  Access and use of buildings

6.15.2.9.1  WC facilities

Wherever possible the entrance storey should contain WC facilities. Where this is not possible, the stairs from the entrance storey to the storey above or below (whichever contains the bathroom) should be wide enough for a stair-lift to be fitted.

p.836

Note: The requirement does not apply to en-suite bathrooms or showers that are additional to the provision for a WC on the entrance storey.

p.837

6.15.2.9.2  Provision for accessible and wheelchair-adaptable bathrooms

The provision of WC and sanitary facilities that are accessible and/or wheelchair-adaptable is an optional requirement. The following is a summary of the main areas you should consider if you wish to go down this route.

p.838

6.15.2.10  electrical safety

6.15.2.10.1  Notifiable work

6.16  Electrical safety – dwellings

6.1.6.1  Requirements

All electrical work shall be carried out in accordance with Amendment No. 3 (2015) to BS 7671 (Requirements for Electrical Installations, commonly referred to as the IEE Wiring Regulations, 17th edition).

p.839

Note: Although the main requirements for electrical safety are contained in Approved Document P, other associated requirements are scattered throughout the other Approved Documents and these are noted in the text below.

The 2006 version of Approved Document P duplicated much of that contained in BS 7671. This standard had been developed from the Institution of Engineering Technology (IET)’s Wiring Regulations, which were first implemented in 1882 ‘for the prevention of fire risks from electric lighting’. With the upgrade of this standard in 2008, and further amendments in 2011, 2013 and 2015, it was decided that, rather than having two documents regulating the same thing, in future all electrical requirements and recommendations for the built environment would use BS 7671 (incorporating Amendment No. 3) and Approved Document P would only apply to electrical installations that are intended to operate at low or extra-low voltage and are:

p.840

and which are designed and installed so that:

Main changes to the 2013 version of Approved Document P

Changes in the legal requirements:

Additional changes as a result of Amendment No. 3 to BS 7671

Potentially life-saving changes have been made to the previous publication, making this a vital update. These changes include (but are not limited to) amendments in the following areas:

Note: The latest edition of this standard has now grown to a massive 489-page document that defines the way in which all electrical installation work must be carried out. It does not matter whether the work is carried out by a professional electrician or an unqualified DIY enthusiast, but the installation must still totally comply with the Wiring Regulations.

These regulations form the basis of safe working practice throughout the electrical industry, but although BS 7671 is well structured and has separate sections for all the main topics (e.g. safety protection, selection and erection of equipment and so on), it is not the easiest of standards to get to grips with for a particular situation. Occasionally, it can be very confusing and requires the reader to constantly flick backwards and forwards through the book to find the information they are looking for.

p.841

For your assistance, one of Ray Tricker’s other ‘In Brief’ books (Wiring Regulations in Brief, 3rd edition) is available from the publisher (www.routledge.com/Wiring-Regulations-in-Brief/Tricker/p/book/9780415526876) or other booksellers.

The intention of this book (similar to that of Ray Tricker’s other ‘In Brief’ books) is to peel away some of the confusion and ‘officialese’ and provide the reader with an on-the-job reference source that can be quickly used without having to delve into the standard.

6.1.6.2  Meeting the requirements

6.1.6.2.1  Fire safety

6.1.6.2.1.1  Smoke alarms

The installation of smoke alarms, or automatic fire detection and alarm systems, can significantly increase the level of safety by automatically giving an early warning of fire.

All new dwellings should be provided with a fire detection and fire alarm system in accordance with the relevant recommendations of BS 5839–6 to at least a Grade D Category LD3 standard.

p.842

Note: If a dwelling is extended, smoke alarms should be provided in all circulation spaces.

p.843

p.844

If more than one alarm is installed, the alarms should be linked so that the detection of smoke or heat by one unit operates the alarm signal in all of them. Smoke alarms/detectors should be sited so that:

6.1.6.2.1.2  Protection of openings and fire-stopping

p.845

6.1.6.2.1.3  Smoke alarms in thatched roofs

6.1.6.2.1.4  Material alterations

6.1.6.2.1.5  Sheltered housing

6.1.6.2.2  Site preparation and resistance to contaminants and moisture

6.1.6.2.2.1  Roofs (resistance to damage from interstitial condensation)

p.846

6.1.6.2.3  Resistance to the passage of sound

6.1.6.2.3.1  Ceiling treatments

Note: Installing recessed light fittings in ceiling treatments can reduce their resistance to the passage of airborne and impact sound.

6.16.2.4  Sanitation, hot water safety and water efficiency

6.16.2.4.1 General

6.16.2.4.2  Water safety devices

Water safety devices normally consist of:

6.16.2.4.2.1  non-self-resetting energy cutouts

p.847

Where a non-self-resetting energy cut-out operates indirectly on another device to interrupt the supply of heat the energy cut-out should comply with the relevant European Standard or the supplier or installer should be able to demonstrate that the device has equivalent performance to that set out in relevant standards.

Where an electrical device, such as a relay or motorized valve, is connected to the energy cut-out, the device should operate to interrupt the supply of energy if the electrical power supply is disconnected.

Where there is more than one energy cut-out, each non-self-resetting energy cut-out should be independent and have a separate motorized valve and a separate temperature sensor.

Where an energy cut-out is fitted, each heat source should have a separate non-self-resetting energy cut-out.

6.16.2.4.2.2  temperature and pressure relief devices

In such cases, there should be a second non-self-resetting energy cut-out independent of the one provided.

p.848

Note: If the installer is registered with a competent person scheme for the installation of unvented hot water systems it will not be necessary for the work to be notified in advance to the BCB.

Fixed building services, including controls, should be commissioned by testing and adjusting as necessary to ensure that they use no more fuel and power than is reasonable in the circumstances.

6.16.2.4.3  Electric water heating

6.16.2.4.4  Solar water heating

p.849

As some solar hot water systems operate at high temperatures and pressures, all components should be rated to the appropriate temperatures and pressures.

6.16.2.5  Drainage and waste disposal

6.16.2.5.1  Materials for pipes fittings and joints

6.16.2.6  Combustion appliances and fuel storage systems

6.16.2.6.1  Cellars or basements

6.16.2.7  Protection from falling, collision and impact

6.16.2.7.1  Safe opening and closing of windows - location of controls

6.16.2.7.2  Power-operated doors

p.850

6.16.2.8  Conservation of fuel and power

6.16.2.8.1  Controlled services

6.16.2.8.2  Commissioning of fixed building services

Not all fixed building services will need to be commissioned. Examples of this would be some mechanical extraction systems or single fixed electrical heaters.

6.16.2.9  Access to and use of buildings

6.16.2.9.1  Services and controls

p.851

6.16.2.9.2  Communal entrances

6.16.2.9.3  Private entrances

6.16.2.9.4  Wheelchair storage and transfer areas

To enable a person to charge and store up to two wheelchairs and transfer between an outdoor and an indoor wheelchair, a dwelling should have a storage and transfer space.

p.852

6.16.2.9.5  Through-floor lifting device provision

Where the dwelling is defined as wheelchair-accessible, a suitable through-floor lift or lifting platform should be installed and commissioned. The following electrical inputs are required:

Note: In a two-storey dwelling, the requirement can typically be met by a home lift to BS 5900 or lifting platforms to BS EN 81–41. However, a lifting platform may require a larger liftway than stated in paragraph 3.29 and may also require a three-phase power supply.

6.16.2.9.6  Private stairs and changes of level within the dwelling

An ambulant disabled person should be able to move within, and between, storeys. It should also be possible to fit a stair-lift to the stairs from the entrance storey to the storey above (or the storey below) where this contains the bathroom.

6.16.2.9.7  Services and controls

To assist wheelchair users who have reduced reach, services and controls should comply with all of the following.

p.853

6.16.2.10  Electrical safety - Dwellings

6.16.2.10.1  Functionality requirements

Approved Document P of the Building Regulations covers the safety of electrical installation work; it does not cover system functionality. Other parts of the Building Regulations and other legislation cover the functionality of electrically powered products such as fire alarm systems, fans and pumps.

It should be remembered that, while Approved Document P does not apply to electrical installations that supply the power for lifts in blocks of flats, it does apply to lift installations in single dwellings.

p.854

Note: Since the last edition of Building Regulations in Brief, the range of electrical installation work that is notifiable (where there is a requirement to certify compliance with the Building Regulations) has been reduced. An installer who is not a registered competent person may use a registered third party to certify notifiable electrical installation work as an alternative to using a BCB.

6.16.2.10.2  General

Low voltage and extra-low voltage electrical installations in dwellings are designed and installed so that both of the following conditions are satisfied:

6.16.2.10.3  Provision of information

6.16.2.10.4  New dwellings

p.855

6.16.2.10.5  New dwellings formed by a change of use

Although in some cases the existing electrical installation will need to be upgraded to meet current standards, if the existing cables are adequate it is not necessary to replace them, even if they use old colour codes.

6.16.2.10.6  Additions and alterations to existing electrical installations

In accordance with the Building Regulations, when building work is complete, the building should be no more unsatisfactory in terms of complying with the applicable requirements of the Regulations than before the work was started.

p.856

6.16.2.10.7  Scope of Approved Document P

p.857

6.16.2.10.8  Notifiable work

Electrical installation work that is notifiable is set out in Regulation 12(6A).

Figure 6.16.6 below illustrates the space around a bath tub or shower tray (a special location) within which minor additions and alterations to existing circuits, as well as the installation of new circuits, are notifiable.

p.858

Note: Notifiable work involves activities (usually electrical) which should be notified by the installer to the Local Authority Building Control. If you are not sure whether the work you want to undertake is notifiable, you should contact your Local Authority Building Control Department for advice.

6.16.2.10.9  Non-notifiable work

6.16.2.10.10  Certifications, inspection and testing

p.859

Note: Electrical inspection and test forms should be given to the person ordering the work. Building Regulations certificates should normally be given to the occupier.

6.16.2.10.11  Self-certification by a registered competent person

6.16.2.10.12  Certification by a registered third party

Note: The electrical installation condition report should be the model BS 7671 form or one developed specifically for Approved Document P purposes.

p.860

6.16.2.10.13  Certification by a Building Control Body

An installer who is competent to carry out inspection and testing should give the appropriate BS 7671 certificate to the BCB, which will take the certificate and the installer’s qualifications into account in deciding what further action, if any, it needs to take. BCBs may ask installers for evidence of their qualifications.

This can result in a lower Building Control charge as, when setting its charge, a Local Authority is required by the Building (Local Authority Charges) Regulations 2010 to take account of the amount of inspection work that it considers it will need to carry out.

Once the BCB has decided that, as far as can be ascertained, the work meets all Building Regulations requirements, it will issue to the occupier a Building Regulations completion certificate (if a Local Authority) or a final certificate (if an Approved Inspector).

6.16.2.10.14  Inspection and testing of non-notifiable work

6.16.2.10.15  Reports and certificates

p.861

p.862

6.16.2.10.16  Fixed internal lighting (domestic buildings)

In order that dwelling occupiers may benefit from the installation of efficient electric lighting, whenever:

p.863

the rewiring works must comply with BS 7671.

Lighting fittings (including lamp, control gear, housing, reflector, shade, diffuser or other device for controlling the output light) should only take lamps with a luminous efficiency greater than 40 lumens per circuit-watt.

p.864

Note: Light fittings in less frequented areas such as cupboards and other storage areas do not count.

6.16.2.10.17  Fixed external lighting

Fixed external lighting (i.e. lighting that is fixed to an external surface of the dwelling and which is powered from the dwelling’s electrical system) should either:

Fixed energy efficient light fittings (one per 25m² dwelling floor area (excluding garages) and one per four fixed light fittings) should be installed in the most frequented locations in the dwelling.

External lighting (including lighting in porches, but not lighting in garages and car ports) should:

6.16.2.10.18  Cables to outside buildings

Cables to an outside building (e.g. garage or shed):

p.865

See BS 7671 or Wiring Regulations in Brief (3rd edition) by Ray Tricker for more information.

6.16.2.10.19  Where can I get more information?

Further guidance concerning the requirements for electrical safety is available from:

To download pdf copies of Approved Document P (and other Approved Documents), go to www.planningportal.gov.uk. For details of fixed wire colour changes, go to www.niceic.org.uk.

6.17  Combustion appliances

6.17.  Requirements

p.866

p.867

6.17.2  Meeting the requirements

Note: Any work associated with a combustion appliance is classed as notifiable building work. In these cases, it will be necessary to notify a BCB in advance of any work starting, unless work is carried out under a self-certification scheme or the work is repair or maintenance. Details of competent person’s schemes can be found at www.communities.gov.uk/planningandbuildingregulations/competentpersonsschemes.

For combustion appliances to continue to work safely and effectively, it is essential that they are adequately and regularly serviced and maintained.

6.17.2.1  Fire safety

Connecting flue pipes and factory-made chimneys should always be guarded if there is a possibility of them being damaged or if they could present a burn hazard (that is not immediately apparent) for people.

Combustion appliances require ventilation to supply them with air for combustion. Ventilation is also required to ensure the proper operation of flues or, in the case of flueless appliances, to ensure that the products of combustion are safely dispersed to the outside air.

p.868

6.17.2.2  Ventilation

Note: The guidance provided with Approved Document F may not be adequate to address pollutants from flueless combustion space heaters or from occasional, occupant-controlled events such as painting, smoking, cleaning or other high-polluting activities.

6.17.2.3  Combustion appliances and fuel storage systems

Note: If internal mechanical ventilation is used to disperse ground gases, it may affect the functioning of combustion appliances and may lead to the spillage of products of combustion into the building.

6.17.2.3.1  Air supply for combustion installations

Combustion appliances need to be installed so that there is an adequate supply of air to them for combustion, to prevent overheating and for the efficient working of any flue.

p.869

Where appliances are to be installed within balanced compartments, special provisions will be necessary.

Note: In a flueless situation, air for combustion (and to carry away its products) can be achieved as shown in Figure 6.17.4.

p.870

If an appliance is room-sealed but takes its combustion air from another space in the building (e.g. the roof void), or if a flue has a permanent opening to another space in the building (e.g. where it feeds a secondary flue in the roof void), that space should have ventilation openings directly to outside.

p.871

Note: Air vents for flueless appliances, however, should open directly to the outside air.

6.17.2.3.2  Air vents

Permanently open air vents should be non-adjustable, sized to admit sufficient air for the purpose intended, and positioned where they are unlikely to become blocked.

p.872

p.873

In noisy areas, it may be necessary to install proprietary noise-attenuated ventilators to limit the entry of noise into the building.

Note: Discomfort from cold draughts can be avoided by placing vents close to appliances (for instance, by using floor vents), by drawing air from intermediate spaces (such as from a hallway) or by placing air vents close to ceilings so as to ensure good mixing of incoming cold air.

6.17.2.3.3  Flues

Appliances other than flueless appliances should incorporate or be connected to suitable flues which discharge to the outside air.

p.874

Note: Chimneys and flues should provide satisfactory control of water condensation.

6.17.2.3.4  Reuse of existing flues

Note: A way of checking before and/or after remedial work would be to test the flue using the procedures in Appendix E of Approved Document J. Defective flues could then be relined using the materials and components described in Sections 2, 3, and 4 of Approved Document J.

6.17.2.3.5  Configuration of natural draught flues serving open-flued appliances

Flue systems should offer least resistance to the passage of flue gases by minimizing changes in direction or horizontal length.

p.875

Note: 90° factory-made bends, elbows or T-pieces in fluepipes may be treated as being equal to two 45° bends (see Figure 6.17.9).

6.17.2.3.6  Condition of combustion installations at completion

p.876

6.17.2.3.8  Access to combustion appliances for maintenance

6.17.2.3.9  Hearths

6.17.2.3.10  Appliances fitted in bathrooms and shower rooms

Note: If the location of these devices in such rooms in totally unavoidable, a way of meeting the requirements would be to provide room-sealed appliances.

6.17.2.4  Conservation of fuel and power

6.17.2.4.1  Controlled services

p.877

6.17.2.4.2  Secondary heating in a dwelling

6.18  Hot water storage

6.18.1  Requirements

p.878

p.879

6.18.2  Meeting the requirements

6.18.2.1  Sanitation, hot water safety and water efficiency

6.18.2.1.1  Hot water supply and systems

All electrical work associated with hot water systems shall be carried out in accordance with Amendment No. 3 (2015) to BS 7671 (Requirements for electrical installations, commonly referred to as the IEE Wiring Regulations, 17th edition).

p.880

6.18.2.1.2  Hot water storage systems

Pipework should be designed and installed in such a way as to minimize the transfer time between the hot water storage system and hot water outlets.

6.18.2.1.3  Vented hot water storage systems

p.881

6.18.2.1.4  Unvented storage system

The installation of an unvented system is notifiable building work which must be reported to the BCB before work commences, unless the installer is registered with a competent person scheme, in which case the installer may self-certify that the work complies with all relevant requirements in the Building Regulations and provide the building owner or occupier with a certificate of compliance.

p.882

Any unvented hot water storage system unit or package should be indelibly marked (see Figure 6.274) with the following information:

p.883

6.18.2.1.5  Commissioning heating and hot water systems

When commissioning a heating and/or hot water system, the following should be included in the test and inspection schedule:

In addition, when commissioning heating and hot water systems, the person carrying out the commission should ensure that:

p.884

The person carrying out the work shall provide the Local Authority with a notice confirming that all fixed building services have been properly commissioned in accordance with a procedure approved by the Secretary of State.

Note: The tundish should incorporate a suitable air gap.

6.18.2.2  Conservation of fuel and power

6.18.2.2.1  Commissioning heating and hot water systems

Reasonable provision should be made to limit heat losses from pipes as set out in DCLG’s Domestic Building Services Compliance Guide. This includes insulating primary circulation pipes for domestic hot water services throughout their length.

p.885

Obviously not all fixed building services will need to be commissioned, as the only controls are possibly ‘ON’ and ‘OFF’ switches (e.g. a mechanical extraction system or single fixed electrical heater).

Any heating system more than 15 years old should either be replaced or be equipped with improved controls.

p.886

6.19  Liquid fuel

6.19.1  Requirements

p.887

Note: A service or fitting for fuel storage is classed as a ‘controlled service or fitting’.

6.19.2  Meeting the requirement

6.19.2.1  Fire safety

Places of special fire hazard include garages, switch gear rooms, boiler rooms, storage space for fuel or other highly flammable substances and rooms housing a fixed internal combustion engine.

6.19.2.1.1  Garages

6.19.2.2  Drainage and waste disposal

6.19.2.2.1  Fuel storage areas

6.19.2.3  Combustion appliances and fuel storage systems

6.19.2.3.1  LPG Storage and supply

LPG storage vessels and LPG-fired appliances fitted with automatic ignition devices or pilot lights must not be installed in cellars or basements.

Oil and liquid petroleum gas (LPG) fuel storage installations (including the pipework connecting them to the combustion appliances in the buildings they serve) shall:

p.888

A firewall will provide a means of shielding a fuel tank from the thermal radiation from a fire. For LPG tanks, it will also ensure that gas accidentally leaking from the tank or fittings must travel by a longer path and therefore disperse safely before reaching a hazard such as an opening in a building, a boundary or other potential ignition source.

Permanently open air vents should be non-adjustable, sized to admit sufficient air for the purpose intended and positioned where they are unlikely to become blocked.

Ventilators should be installed so that building occupants are not provoked into sealing them against draughts or noise. Ventilation openings should not be made in fire-resisting walls other than external walls (although they should not penetrate those parts of external walls shielding LPG tanks).

Air vents should not be located within a fireplace recess except on the basis of specialist advice.

The Gas Safety (Installation and Use) Regulations control all aspects of the ways combustion systems fired by gas (including natural gas and LPG) are installed, maintained and used, mainly in domestic and commercial premises, and the classes of persons who may undertake gas work.

p.889

6.19.2.3.2  Heating, oil storage (in England)

In England, oil storage tanks which serve buildings which are not wholly or mainly used as private dwellings are likely to be subject to the Control of Pollution (Oil Storage) (England) Regulations 2001.

Note: Regulations relating to heating oil include BS 2869, EN 14213 and BS 5410–1.

6.19.2.3.3  Protective measures against fire

6.19.2.3.4  Oil pollution

The main problems with regard to leakage concerns inland freshwater streams, rivers, reservoirs and lakes, as well as ditches and ground drainage (e.g. perforated drainage pipes) that feed into them.

The Control of Pollution (Oil Storage) (England) Regulations 2001 (SI 2001/2954) came into force on 1 March 2002 and they apply to a wide range of oil storage installations in England. But they do not apply to the storage of oil on any premises used wholly or mainly as one or more private dwellings, if the capacity of the tank is 3500 litres or less.

p.890

Inland freshwaters include streams, rivers, reservoirs and lakes, as well as ditches and ground drainage (including perforated drainage pipes) that feed into them.

Authors’ note: Oil storage below ground should only be considered when no other option is available. Underground tanks are difficult to inspect and leaks may not be immediately obvious.

6.19.2.3.5  Liquefied petroleum gas

p.891

p.892

Note: Further guidance on LPG pipework can be found in the Gas Safety (Installation and Use) Regulations 1998 (GSIUR), the UKLPG Code of Practice 22 and the Institution of Gas Engineers and Managers standard IG/TD/4.

p.893

6.20  Kitchens and utility rooms

6.20.1  Requirements

p.894

6.20.2  Meeting the requirements

6.20.2.1  Fire safety

6.20.2.1.1  Smoke alarms

Note: Detectors respond differently to smouldering and fast-flaming fires and therefore should, if possible, take into account the type of fire that might be expected and the need to avoid false alarms. Optical detectors are generally more suitable for installation in circulation spaces adjacent to kitchens.

6.20.2.1.2  Escape routes

p.895

Cold water pipes that pass through a compartment wall or compartment floor (unless the pipe is in a protected shaft), or through a cavity barrier, should incorporate one of the following alternatives:

p.896

6.20.2.1.3  Refuse chutes and storage

In buildings containing flats, any wall that encloses a refuse storage chamber should be constructed as a compartment wall. Refuse storage chambers, refuse chutes and refuse hoppers should be sited and constructed in accordance with BS 5906.

6.20.2.2  Site preparation and resistance to contaminants and moisture

6.20.2.2.1  Floor coverings

Note: Chipboard should be of a grade with improved moisture resistance (BS 7331 or BS EN 312). It should be laid, fixed and jointed in the manner recommended by the manufacturer. To demonstrate compliance, the identification marks face upwards. Any softwood boarding should be at least 20mm thick and from a durable species or treated with a suitable preservative.

p.897

6.20.2.2.2  Roofs

To avoid excessive moisture transfer to roof voids the gaps and penetrations for pipes and electrical wiring should be filled and sealed. This is particularly important in areas of high humidity, e.g. kitchens. An effective draught seal should be provided to loft hatches to reduce inflow of warm air and moisture.

The requirement will be met by the ventilation of cold deck roofs, i.e. those roofs where the moisture from the building can permeate the insulation. For the purposes of health and safety it may not always be necessary to provide ventilation to small roofs such as those over porches and bay windows.

Any part of a roof which has a pitch of 70° or more should be insulated as though it were a wall.

6.20.2.3  Resistance to the passage of sound

6.20.2.3.1  Refuse chutes

6.20.2.3.2  Tests for sound between rooms

p.898

6.20.2.4  Ventilation

Extract ventilation may be by natural means such as by Passive Stack Ventilation (PSV) or by mechanical means such as an extract fan or central system, but note that it is now a mandatory requirement that, if you carry out any ‘building work’ and there is an existing extract fan, PSV or cooker hood extracting to outside in the kitchen, you should either retain or replace it.

6.20.2.4.1  The purpose of ventilation

The pollutant(s) of most importance will vary between building types and building and the common pollutants in a dwelling are moisture and combustion products from unflued appliances (e.g. gas, oil or solid fuel cookers) and chemical emissions from construction and consumer products.

The ventilation system capacity, if used appropriately, is usually sufficient to remove odours arising from normal occupant activities within a dwelling.

6.20.2.4.2  Control of ventilation

p.899

Note: Manual boost controls should also be provided in kitchens to guard against the possibility of a single centrally located switch being left in an incorrect mode of operation.

6.20.2.4.3  Ventilation rates

p.900

If any of the work being carried out in the kitchen of an existing building is ‘building work’ (as defined in Regulation 3 of the Building Regulations) then you will need to comply with the appropriate requirements of this regulation.

p.901

6.20.2.4.4  Refurbishing a kitchen or bathroom in an existing dwelling

The definition of ‘building work’ in Regulation 3 of the Building Regulations includes a range of building activities in existing buildings, and includes all work on controlled services. For more information, see the Building Regulations at www.planningportal.gov.uk.

Appendix C to Approved Document F gives example calculations for ventilation sizing for dwellings

6.11.2.5  Sanitation, hot water safety and water efficiency

Note: Kitchen means a room or part of a room which contains a sink and food preparation facilities.

6.20.2.5.1  Sanitary conveniences and washing facilities

Note: In dwellings, a room containing both a sanitary convenience and a basin for hand washing does not need a separation lobby between this room and a kitchen or food preparation area (Figure 6.20.1). The layout for a room containing a sanitary convenience only should be such that the room or space containing its associated hand-washing facilities is accessed before entry to a food preparation area, and is separated from that area by a door (Figure 6.20.2).

p.902

p.903

6.20.2.5.2  Chemical or composting toilets

6.20.2.5.4  Scale of provision in dwellings

6.20.2.5.5  Discharges to drains

Note: Approved Document H1 provides guidance on drainage, the provision for traps, discharge pipes and stacks and foul drains.

6.20.2.5.6  Cold water supplies

The cold water supply shall:

6.20.2.5.7  Cold water storage systems

6.20.2.5.8  Storage of food

In accordance with Building Act 1984 Sections 28 and 70, all houses or buildings that have been converted into dwellings must provide sufficient and suitable accommodation for storing food or ‘sufficient and suitable space for the provision of such accommodation by the occupier’.

p.905

6.20.2.5.9  Alternative sources of water

6.20.2.6  Drainage and waste disposal

6.20.2.7  Access to and use of buildings

Requirements M4(2) and M4(3) of Approved Document M Volume 1 (referred to as M1) are optional requirements. There are no compulsory requirements relating to access in kitchens.

6.20.2.7.1  Living, kitchen and eating areas

p.906

Note: Drawings should be provided which show how the kitchen could be easily adapted to meet the requirements for accessible dwellings at a future date without compromising the space in any other part of the dwelling and without the need to move structural walls, stacks or concealed drainage.

p.907

6.20.2.7.2  Through-floor lifting device provision

6.20.2.8  Electrical safety – dwellings

p.908

6.21  Loft conversions

6.21.1  Requirements

p.909

p.910

6.21.2  Meeting the requirement

6.21.2.1  Fire safety

Where the conversion of an existing roof space (e.g. a loft conversion to a two-storey house) means that a new storey is going to be added, then the stairway will need to be protected with fire-resisting doors and partitions.

p.911

Note: If it is considered undesirable to replace existing doors (e.g. if they are of historical or architectural merit), it may be possible to retain the doors or upgrade them to an acceptable standard

6.21.2.2  Resistance to contaminants

Care should be taken when working on sites affected by contaminants where control measures are already in place not to compromise these measures.

p.912

6.21.2.3  Cavity insulation

Fumes given off by insulating materials such as by urea formaldehyde (UF) foams should not be allowed to penetrate occupied parts of buildings where they could become a health risk to persons in the building touching an irritant concentration.

6.21.2.4  Resistance to the passage of sound

New walls and floors within a dwelling should provide a minimum sound insulation value of 40 R_W dB.

Special attention also needs to be given to situations where flanking walls or floors are continuous across separating walls or floors as a result of the conversion work. In such instances, additional treatments may be required to control flanking transmission along these continuous elements. Specialist advice may be needed.

Significant differences may frequently occur between the construction and layout of each converted unit in a development. In these cases, the Building Control Body (BCB) will provide guidance concerning:

p.913

6.21.2.5  Ventilation

If the additional room is connected to an existing habitable room has:

If the extension is the addition of a habitable room to an existing building, then:

p.914

Care should be taken when installing ducting for fans through an unheated void or loft space.

Note: Avoid peaks and troughs in ducting and consider the use of condensation traps to prevent the backflow of moisture where necessary.

6.21.2.6  Sanitation, hot water safety and water efficiency

The regulations relating to sanitation apply equally to loft conversions. If you plan to install a bathroom in a loft conversion, see Chapter 6.15 of this book.

6.21.2.7  Protection from falling, collision and impact

You may use alternating tread stairs – in one or more straight flights – only in a loft conversion, and only when there is not enough space for a stair that satisfies paragraphs 1.2–1.24 of Approved Document K, and the stair is for access to only one habitable room and, if desired, a bathroom and/or a WC.

p.915

p.916

Note: This requirement applies to stairs that form part of the building.

6.21.2.8  Conservation of fuel and power

6.21.2.8.1  Retained thermal elements

Thermal elements may be retained when an existing element becomes part of the thermal envelope where previously it was not, e.g. as part of a loft conversion or where an existing thermal element is part of a building which is subject to a material change of use.

When upgrading retained thermal element particular attention should be paid to Approved Documents F and J.

p.917

6.21.2.8.2  Work covered by Approved Document L1B

Approved Document L1B provides guidance for those carrying out work on existing dwellings on what is considered to be compliance with the Regulations. Under Regulation 17D of the Building Regulations, the construction of a loft extension will trigger the requirement for consequential improvements.

Note: Buildings exclusively containing rooms for residential purposes such as nursing homes, student accommodation and similar are not dwellings, and are covered in Chapter 7.

6.21.2.8.3  Material change of use

Changes which constitute a material change of use may require thermal elements to be upgraded.

p.918

Note: A material alteration may result in a change in buildings energy status.

6.21.2.8.4  Change of energy status

Changes which result in a building now becoming subject to the regulations where previously it did not are called a change of energy status.

In this regulation ‘building’ means the building as a whole or parts of the building that have been designed or altered to be used separately. For example, this could occur if a previously unheated building, or parts of the building that have been designed or altered to be used separately, were to be heated in future, or where a previously exempt building were no longer within the exempted categories.

p.919

To provide more design flexibility, SAP 2012 can be used to demonstrate that the total C0₂ emissions from all the dwellings in the building as it will become are no greater than if each dwelling had been improved following the guidance set out in paragraph

If you are adding a loft conversion, make sure any conservatory does not restrict ladder access to windows serving rooms in the loft conversions, particularly if any of the windows are intended to help escape or rescue if there is a fire.

6.21.2.9  Security

The new Approved Document Q (Security) applies to any dwelling (or part of a building from which access can be gained to a flat within that building) and requires secure doors and windows to be fitted in dwellings.

p.920

6.22  Extensions and additions to buildings

This section covers specific guidance relating to Extensions and Additions. Any requirements covered by other sections of this chapter e.g. Loft conversions (Section 6.22) and Conservatories (6.24) should be used in conjunction with this section.

6.22.1  Requirements

p.921

p.922

The construction of an extension may trigger the requirement for “consequential improvements” (Regulation 17D of the Building Regulations). For example, if a building has a total useful floor area greater than 1000m³ and the proposed building work includes an extension, or the initial provision of any fixed building service, or an increase to the installed capacity of any fixed building services, consequential improvements should be made to improve the energy efficiency of the whole building and:

Note:

6.22.2  Meeting the requirement

6.22.2.1  Fire safety

The chances of fire spreading across an open space between buildings should be limited as much as possible. At a minimum, the building should not have a lesser level of compliance, after the work has been completed than it did before work commenced.

p.924

Approved Document B includes a requirement for the responsible person (i.e. the person carrying out work to a building) to make available to the owner (other than houses occupied as single private dwellings) ‘fire safety information’ concerning the design and construction of the building or extension, plus details of the services, fittings and equipment that have been provided in order that they may complete a fire risk analysis. The sort of information required must include basic advice on the proper use and maintenance of systems provided in the building such as:

p.925

6.22.2.2  Resistance to contaminants

Care should be taken when working on sites affected by contaminants where control measures are already in place not to compromise these measures (e.g. breaching a cover system when extension foundations are constructed).

p.926

6.22.2.3  Cavity insulation

6.22.2.4  Resistance to the passage of sound

Note: New walls and floors within a dwelling (including extensions) should provide a minimum sound insulation value of 40 R_W dB.

6.22.2.5  Means of ventilation

If the additional room is connected to an existing habitable room has:

If the extension is the addition of a habitable room to an existing building, then:

p.927

6.22.2.6  Sanitation, hot water safety and water efficiency

The regulations relating to sanitation [G1, G3(2) and G3(3)] apply equally to extensions where they share facilities with another building which is covered by the Regulations.

p.928

Note: The Regulations do not require hot or cold water systems to be provided to exempt buildings. If systems are provided, then they must meet the minimum hygiene and safety requirements laid out in the Approved Documents.

6.22.2.7  Conservation of fuel and power

6.22.2.7.1  Changes in the legal requirements

Some extensions are exempt from the energy efficiency requirements of the Building Regulations. This exemption only applies where the existing doors are retained (or replaced) and where the extension:

If a new extension does not meet all the requirements above then it is not exempt and must comply with the relevant energy efficiency requirements of Approved Document L, and reasonable provision should be provided to ensure that:

Doors which have less than 50 percent of their internal face glazed should not exceed 1.8 W/m² K

If a building extension is not exempt from the energy efficiency requirements, then:

p.929

If you remove but do not replace any of the thermal separation between the building and an existing exempt extension, or you extend the building’s heating system into the extension then the extension will no longer be exempt!

In most circumstances the most reasonable provision would be to limit the total area of windows, roof windows and doors in extensions so that it does not exceed the sum of:

p.930

Where the proposed extension has a total useful floor area that is both greater than 1000m²; and greater than 25 percent of the total useful floor area of the existing building then the work should be regarded as a new building.

One way of complying would be to show that the area-weighted U-value of all the elements in the extension is no greater than that of an extension of the same size and shape.

6.22.2.7.2  Historic and traditional buildings

When undertaking work on any historic or traditional building, the aim should always be to improve energy efficiency as far as is reasonably practicable without prejudicing the character of the host building or increasing the risk of long-term deterioration of the building fabric or fittings.

Building Inspectors normally require the use of ‘sympathetic treatment’ when restoring the historic character of a building that has been subject to previous inappropriate alteration (e.g. replacement doors).

p.931

Particular issues that could warrant sympathetic treatment include:

6.22.2.8  Access to and use of buildings – optional requirement

Providing access able doorways to conservatories in dwellings is an optional requirement should you wish to follow the following sections of Approved Document M4 (2)

p.932

6.22.2.9  Security

The new Approved Document Q (Security) applies to any dwelling or part of a building where access can be gained to a flat within that building and the requirement is for secure doors and windows to be fitted in that dwelling.

p.933

6.23  Conservatories

6.23.1  Requirements

p.934

Conservatories, porches and domestic greenhouses that share their electricity with a dwelling are not exempt from Part P (Electrical Safety) and must comply with its requirements.

Note: Until May 2019 ,under permitted development in England, householders may build larger single-storey conservatories of up to 8m² for detached houses and 6m² for all other houses. More information is contained in Chapters 4 and 5.

Requirement R (Physical infrastructure for high-speed electronic communications networks) does not apply to conservatories and other small detached buildings which have no sleeping accommodation.

6.23.2  Meeting the requirement

6.23.2.1  Fire safety

Some roof coverings (such as plastic roof lights) do not provide protection against the spread of fire and therefore are not permitted adjacent to a boundary.

6.23.2.2  Ventilation

The general ventilation rate for conservatories (and adjoining rooms) with a floor area greater than 30m², can be achieved by the use of background ventilators (e.g. air bricks).

p.935

p.936

Note: Further guidance on the size of purge ventilation, and the location and control of this ventilation in new dwellings is given in Section 6.2.

6.23.2.3  Sanitation

The regulations relating to sanitation apply equally to conservatories where they share facilities with another building which is covered by the Regulations.

p.937

Note: The Regulations do not require hot or cold water systems to be provided in exempt buildings, but if systems are provided they must meet the minimum hygiene and safety requirements in the Approved Documents.

6.23.2.4  Conservation of fuel and power

Conservatories in a new dwelling should follow the guidance of Approved Document L1B with regard to energy efficiency unless the dwelling’s heating system is extended into the conservatory or there is inadequate (or no) thermal separation between the dwelling and the conservatory – in which case Approve Document L1A applies.

6.23.2.4.1  New dwellings

Where conservatories are installed at the same time as the construction of a new dwelling:

Under Regulation 17D of the Building Regulations, the construction of a conservatory may trigger the requirement for consequential improvements.

A conservatory extension in an existing dwelling is exempt from the regulations as long as the existing walls, windows and doors are retained (or replaced) and the heating system is not extended into the conservatory.

p.938

Where the conservatory is not exempt from the energy efficiency requirements:

Note: The limitations set out in Approved Document L1B 4.2 on total permittable areas of windows, roof windows and doors do not apply in the case of conservatories.

p.939

Notes:

6.23.2.5  Access to and use of buildings – optional requirement

Providing access able doorways to conservatories in dwellings is an optional requirement should you wish to follow the following sections of Approved Document M4 (2).

p.940

6.23.2.6  Security

The new Approved Document Q (Security) requires secure doors and windows to be fitted in dwellings and/or part of a building from which access can be gained to a flat within the building.

p.941