•    Information in the shaded box is either a paraphrase of the requirement or the requirement itself.

•    Each separate row contains a paragraph of the Approved Document as a separate bullet.

    Subpoints are further indented.

    Supplemental information is also further indented.

•    As shown in Figure 7.1.1, in a small single-storey non-residential buildings the:

•    The U-value of the basin in a swimming pool (the walls and floor) should be a minimum of 0.25W/m²K (calculated in accordance with BS EN ISO 133705).

•    The effects of insulation boards not being fully supported or point loading should be considered.

•    Thermal bridging around basin wall and floor junctions with foundations should be avoided.

•    If an air circulation system circulates air only within an individual flat with an internal protected stairway or entrance hall:

    transfer grilles should not be fitted in any wall, door, floor or ceiling enclosing a protected stairway or entrance hall

    ducts passing through enclosures should be constructed of rigid steel

    all joints between the ductwork and an enclosure should be fire-stopped

    ventilation ducts for protected areas should not also serve other areas

    mechanical ventilation which recirculates air and serves both a stairway or entrance hall and other areas should shut down on the detection of smoke within the system.

•    A ducted warm air heating system thermostat should be mounted on the living room wall (between 1370mm and 1830mm); its maximum setting should not exceed 27°C.

•    Every flat in small single-stair building does not need access to alternative escape routes if:

    the stair does not also serve ancillary accommodation, unless there is a protected lobby or corridor with permanent ventilation or a mechanical smoke-control system between them

    each floor level has a high level openable vent with a minimum free area of 1m²

    the head of the stairs has a single openable vent which is remotely operated from fire and rescue service access level.

•    In buildings (other than small ones) the corridor adjoining a stair should have a vent, and:

    the vent should be as high as practicable

    the top edge of the vent should be at least as high as the top of the door to the stair

    there should also be a vent with a free area of at least 1.0m² from the top storey of the stairway to the outside.

•    In single-stair buildings smoke vents on the fire floor and at the head of the stair should be actuated by smoke detectors in the common access space.

•    In buildings with more than one stair the smoke vents may be actuated manually.

    Smoke detectors are not required.

    The control system should ensure that the vent at the head of the stair is opened either before, or at the same time, as the vent on the fire floor.

•    Vents should either:

    be on an external wall with minimum free area of 1.5m²; or

    discharge into a vertical smoke shaft (closed at the base) which meets the following:

    cross-sectional area of 1.5m² (minimum 0.85m)

    open at roof level at least 0.5m above any surrounding structures within a horizontal distance of 2.0m.

    extending at least 2.5m above the ceiling of the highest storey

    the free area of the vent from the corridor/lobby into the shaft and at the head of the shaft’s opening and all internal locations should be at least 1.0m²

    the smoke shaft should be constructed from non-combustible material

    vents should have fire resistance performance equivalent to an E30S_a fire door

    the shaft should be vertical from base to head

    the shaft should have no more than 4m at an inclined angle (maximum 30°)

    on detection of smoke in the common corridor/lobby, the vent(s) on the fire floor, the vent at the top of the smoke shaft and to the stairway should all open simultaneously. The vents from the corridors/lobbies on all other storeys should remain closed.

•    Guidance on mechanical ventilation is available in BS EN 12101-6.

•    If the stair serves an enclosed car park, or place of special fire hazard, lobbies or corridors should have 0.4m² permanent ventilation or a mechanical smoke-control system.

•    A protected lobby should have not less than 0.4m² permanent ventilation or have a mechanical smoke-control system.

•    Ductwork in mechanical ventilation systems should not transfer fire and smoke through the building.

•    Exhaust points should be sited away from final exits, combustible building cladding or roofing materials and openings into the building.

•    Ventilation ducts supplying or extracting air directly to or from a protected escape route should not serve other areas.

•    A separate ventilation system should be provided for each protected stairway.

•    Where the ductwork system serves more than one part of a subdivided escape route, a fire damper should be provided where ductwork enters each section of the escape route operated by a smoke detector or suitable fire detection system.

•    Fire dampers should close when smoke is detected.

•    Ducts passing through the enclosure of a protected escape route should be fire-resisting.

•    Smoke detectors should be fitted in the extract ductwork of a system which recirculates air before the point of separation of the recirculated air and the air to be discharged to the open air and before any filters or other air cleaning equipment. Such detector(s) should:

    cause the system to immediately shut down on detection of smoke

    switch the ventilation system from recirculating mode to extraction to open air to divert the any smoke to the outside of the building.

•    Non-domestic kitchens, car parks and plant rooms should have separate and independent extraction systems and the extracted air should not be recirculated.

•    Guidance on the use of mechanical ventilation in a place of assembly is in BS 5588-6.

•    Where a pressure differential system is installed, ventilation and air-conditioning systems in the building should be compatible with it when operating under fire conditions.

•    BS 5720 provides guidance on the design and installation of mechanical ventilation and air-conditioning plant. Guidance on the provision of smoke detectors in ventilation ductwork can be found in BS 5839-1.

•    Rooms containing refuse chutes, or provided for the storage of refuse, should be approached either directly from the open air or by way of a protected lobby provided with not less than 0.2m² of permanent ventilation.

•    Ventilation ducts may pass through openings in compartment walls or compartment floors.

•    If ventilation duct passes through or is built into a compartment wall or compartment floor each wall of the duct should have a fire resistance of at least half that of the wall or floor.

•    Any shaft passing directly from one compartment to another should be enclosed in a protected shaft.

•    The construction enclosing a protected shaft (see Figure 7.2.1) should:

    form a complete barrier to fire between the different compartments which the shaft connects

    have 30 minutes’ fire resistance unless it is an uninsulated glazed screen

    comply with paragraphs 8.41 and 8.42 of Approved Document B2.

•    If a protected shaft contains a stair and/or a lift, it should not also contain a pipe conveying oil (other than in the mechanism of a hydraulic lift) or contain a ventilating duct (other than a duct that ventilates or pressurizes the stairway to keep it smoke free).

•    A protected shaft for piped flammable gas should be ventilated direct to the outside air by ventilation openings at high and low level in the shaft.

•    Any extension of a storey floor into a ventilation shaft should not compromise the free movement of air over the entire length of the shaft.

•    Guidance on such shafts is in BS 8313.

•    Where air handling ducts pass through fire-separating elements the integrity of those elements should be maintained.

•    There are three basic methods of protection:

    Method 1: Protection using fire dampers:

    Not suitable for extract ductwork serving kitchens because of the build-up of grease within the duct which can adversely affect the effectiveness of any dampers.

    Further information on fire-resisting ductwork is given in the ASFP Blue Book: Fire Resisting Ductwork (ISBN: 1 87040 926 4).

    Method 2: Protection using fire-resisting enclosures.

    Method 3: Protection using fire-resisting ductwork.

•    Guidance on the design and installation of mechanical ventilation and air-conditioning plant is in BS 5720 and on ventilation and air-conditioning ductwork in BS 5588-9.

•    There is a low probability of fire spread between storeys if the car park is well ventilated.

•    There are three ventilation methods:

    open-sided (high level of natural ventilation)

    natural ventilation:

    each storey of a car park that is not open-sided should be ventilated by permanent openings (which can be at ceiling level) on each car parking level

    the aggregate free vent area should not be less than 1/40 of the floor area at that level, of which at least half should be split equally and provided between two opposing walls (1/160 on each side)

    mechanical ventilation:

    provided in most basement car parks and in enclosed car parks where it is not possible to obtain the minimum standard of natural ventilation. The system should:

    be independent of any other ventilating system and operate at ten air changes per hour in a fire condition

    run in two parts, each part capable of extracting 50 percent of the rate set out above and designed so that each part may operate singly or simultaneously

    have an independent power supply for each part of the system which operates in the event of failure of the air supply

    arrange extract points so that 50 percent are at high level and 50 percent at low level

    have fans rated to run at 300°C for a minimum of 60 minutes

    have ductwork and fixings constructed of materials with melting point not less than 800°C.

•    Some canopy structures are exempt from the Building Regulations by falling within Class 6 or Class 7 of Schedule 2 to the Regulations (Exempt Buildings and Works).

•    Canopies that do not meet the exemption criteria may find the provisions in Approved Document B2 on limits of unprotected areas onerous.

•    Where a canopy is attached to the side of a building, provided that the edges of the canopy are at least 2m from the relevant boundary, the separation distance may be determined from the wall rather than the edge of the canopy.

•    In view of the high degree of ventilation and heat dissipation achieved by the open-sided construction of a free-standing canopy structure above a limited risk or controlled hazard (e.g. over petrol pumps), and provided the canopy is 1000mm or more from the relevant boundary, the provisions for space separation could be disregarded.

•    For most buildings, basic information on the location of fire protection measures should be provided showing any smoke-control system(s) (or ventilation system with a smoke-control function), including mode of operation and control systems.

•    The pollutant(s) of most importance will vary between building types (e.g. dwelling, office, factory), building uses (e.g. industrial process, shop, commercial kitchen), and from room to room within a building (e.g. kitchen, shower room, conference room, photocopier room).

•    In an office building, body odour is often the key pollutant, but there are a number of other pollutant sources including the building itself, furnishings, printers and photocopiers.

•    Offices are assumed to have an air permeability of 3m³/ (h.m²) at 50 Pa.

•    In large buildings (low ratio of surface area to volume contained), infiltration can be assumed to be negligible compared with the purpose provided ventilation.

•    The ventilation effectiveness is 0.9.

•    The total outdoor air supply rate for offices is 10 l/s per person.

    There is little advantage in increasing the whole building ventilation rate above 10 l/s/p as increased ventilation has a cost in economic and environmental terms.

    If further improvements in indoor air quality are necessary, alternative approaches should be considered first, e.g. use of low-emission materials.

•    During the heating season, the surface water activity in a room should not exceed:

    0.75 in one month

    0.85 in one week

    0.95 in one day.

•    Pollutants from office equipment (ozone and organic compounds) require an extract rate of 20 l/s per machine during use.

•    Extract rates for sanitary accommodation are the same as for dwellings.

•    Extract rates for food and beverage preparation areas are the same as dwellings.

•    It is simpler to remove high concentrations of pollutants from office spaces than from dwellings (e.g. leaving rooms unoccupied until acceptable pollutant levels are achieved).

•    The following guidance is for the range of building types and uses below:

    offices

    car parks

    other building types.

•    The ventilation provisions will not necessarily meet cooling needs.

•    Fresh air supplies should be protected from contaminants injurious to health.

•    Guidance on the siting of air inlets is provided in Appendix D to Approved Document F.

•    Guidance on design measures to avoid legionella contamination, including design features not related to the ventilation of the building, is given in the HSE document Legionnaires’ Disease: The Control of Legionella Bacteria in Water Systems.

•    Further guidance may be found in CIBSE TM13 Minimising the Risk of Legionnaires’ Disease and in BSRIA Application Guides AG19/2000, AG20/2000 and AG21/2000.

•    Guidance on recirculated air in air-conditioning and mechanical ventilation systems is given in HSE document L24 Workplace Health, Safety and Welfare, Workplace (Health, Safety and Welfare) Regulations 1992, Approved Code of Practice and guidance.

•    Adequate space should be provided in a central plant room for the maintenance of the plant.

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

•    Additional space may be needed for access doors, withdrawal of filters, etc.

•    Guidance for complex situations is in Defence Works Functional Standard, Design and Maintenance Guide 08: Space Requirements for Plant Access Operation and Maintenance.

•    Guidance for the cleaning of ducts is provided by CIBSE Ventilation Hygiene Toolkit and HVCA TR/19 – Guide to good practice: Internal Cleanliness of Ventilation Systems.

•    There are four ways to comply with the ventilation requirements of the Building Regulations:

    provide a ventilation system which meets the air flow rates in paragraphs 6.9 to 6.13

    follow the system guidance in paragraphs 6.14 and 6.15

    use one of the alternative approaches set out in paragraph 6.16

    use other ventilation systems, provided it can be demonstrated to the Building Control Body that they satisfy the Requirement.

•    Ventilation should provide the air flow rates set out in paragraphs 6.10 to 6.13 (below).

•    The air flow rates specified in this Approved Document are for the installed performance.

•    Extract to outside is required in all office sanitary accommodation, washrooms and food and beverage preparation areas.

•    Printers and photocopiers in substantial use (greater than 30 minutes per hour) should be located in a separate room with extract provision.

•    The extract flow rates should be no less than those specified in Table 7.2.1.

•    The total outdoor air supply rate for offices is 10 l/s per person.

•    Purge ventilation is required in each office.

•    The total ventilation should be sufficient to reduce pollutants to an acceptable level before the space is occupied.

•    The purged air should be taken directly to outside and should not be recirculated to any other part of the building.

•    The outdoor air supply rates for offices is based on controlling body odours with low levels of other pollutants.

•    Where there are significant levels of other pollutants, adequate outdoor air supply can be achieved by following the calculation method provided in CIBSE Guide A.

•    The air flow rates specified in the Approved Document can be provided by a mainly natural ventilation system by following the following guidance:

    Extract rates as per paragraph 6.10 and Table 7.2.1.

    Whole building ventilation – See CIBSE Application Manual AM 10: Natural ventilation in non-domestic buildings.

    Purge ventilation – See CIBSE Application Manual AM 10: Natural ventilation in non-domestic buildings.

    Passive stack ventilators (PSV) can be used as an alternative to a mechanical extract fan for office sanitary, washroom and food preparation areas.

    When an open-flued appliance is provided in a building with mechanical extract, the spillage of flue gases could occur.

    The open-flued appliance needs to operate safely whether or not the fan is running.

    Further guidance is provided in BS 5440-1.

    Extract ventilators should be located as high as practicable and preferably less than 400mm below the ceiling.

    PSV extract terminals should be located in the ceiling of the room.

    Extract fans should be controlled either manually or automatically.

    For a room with no openable window (i.e. an internal room), the extract should have a 15-minute overrun.

    PSV may be operated manually and/or automatically by a sensor or controller.

    Readily accessible override controls should be provided for the occupants.

•    A wide range of natural ventilation systems for providing whole building ventilation is given in CIBSE Application Manual AM 10: Natural ventilation in non-domestic buildings.

•    The requirement will be satisfied by following:

    the air flow rates set out in paragraphs 6.9 to 6.13 (above); and

    the location and control guidance above is followed for extract ventilation.

•    An alternative approach can be satisfied by following the recommendations of:

    CIBSE Application Manual AM 13: Mixed mode ventilation

    CIBSE Guide A and CIBSE Guide B.

•    The Workplace (Health, Safety and Welfare) Regulations 1992 apply to most places where people work.

•    A short guide, INDG244, is available from the HSE.

•    Enclosed-type and multistorey car parks should have ventilation equipment that limits the carbon monoxide to:

    a maximum average concentration of 30 parts per million over an eight-hour period

    maximum peak concentration of 90 parts per million for periods not exceeding 15 minutes in areas such as by ramps and exits.

•    The following would also satisfy the requirement:

    In naturally ventilated car parks: well-distributed permanent natural ventilation, e.g. openings at each car parking level with an aggregate equivalent area equal to at least 1/20 of the floor area at that level (at least 25 percent on each of two opposing walls).

    In mechanically ventilated car parks:

    either permanent natural ventilation openings of equivalent area not less than 1/40 of the floor area and a mechanical ventilation system capable of at least three air changes per hour (ach); or for basement car parks a mechanical ventilation system capable of at least six ach.

    for exits and ramps a local ventilation rate of at least ten ach.

•    Further guidance can be found in Code of practice for ground floor, multistorey and underground car parks published by the Association for Petroleum and Explosives Administration (www.apea.org.uk); CIBSE Guide B Section 2.3.23.3.

•    Systems should have controls to enable the achievement of reasonable standards of energy efficiency in use.

•    Ventilation and air-conditioning system control:

    systems should be subdivided into separate control zones to correspond to each area of the building that has a significantly different solar exposure, or pattern or type of use

    each separate control zone should be capable of independent timing and temperature-control and, where appropriate, ventilation and air recirculation rate

    service should respond to the requirements of the space it serves.

•    Central plant should operate only as and when the zone systems require it. The default condition should be off.

•    In a naturally ventilated building, this is NOT evidence that the internal environment of the building will be satisfactory.

•    Central ventilation specific fan power should be 1.8 l/s.

•    Demand control (mechanical ventilation) should permit variable speed control of fans via CO² sensors.

•    Roof ventilators should have a U-value of 3.5 W/m²K.

•    The approved procedure for pressure testing is given in the Air Tightness Testing and Measurement Association (ATTMA) publication Measuring Air Permeability of Building Envelopes.

•    The preferred test method is that trickle ventilators should be temporarily sealed rather than just closed.

•    Building Control Bodies (BCBs) should be provided with evidence that test equipment has been calibrated within the previous 12 months using a UKAS-accredited facility.

•    When an incoming occupier does first fit-out work on all or part of the building through the provision or extension of any of the fixed services for mechanical ventilation, then TER/BER submission should be made to the BCB after completion to demonstrate compliance for the part of the building covered by the fit-out work.

•    In a ventilation system, the replacement of any part which is not a combustion appliance (such as valve or pump) or the addition of an output device or the addition of a control device is not notifiable.

•    The work will be notifiable whenever commissioning is possible and necessary to enable a reasonable use of fuel and power.

•    The installation of a stand-alone, self-contained ventilation service which consists of a single appliance and any associated controls (as long as

•    they are not connected to any other fixed building service) are non-notifiable, e.g. a mechanical extractor fan in a kitchen or bathroom.

•    If a ventilation appliance is installed in a room containing a natural draught open-flued combustion appliance or service, such as a gas fire which uses a chimney as its flue, it will be notifiable.

•    Where the work involves the provision or extension of a mechanical ventilation service then the guidance set out in the Non-Domestic Building Services Compliance Guide. The Guide should be followed.

•    Pipes which pass through a fire-separating element (unless the pipe is in a protected shaft), should meet the appropriate provisions in alternatives A, B or C below.

•    Alternative A. Provide a proprietary sealing system which maintains the fire resistance of the wall, floor or cavity barrier.

•    Alternative B. Where a proprietary sealing system is not used, fire-stopping may be used around the pipe, keeping the opening as small as possible (the nominal internal diameters of the pipe are given in Table 7.3.1).

•    Alternative C. A pipe of lead, aluminium, aluminium alloy, fibre-cement or uPVC, with a maximum nominal internal diameter of 160mm, may be used with a sleeving of non-combustible pipe as shown in Figure 7.3.1. The specification for non-combustible and uPVC pipes is given in the notes to Table 7.3.1.

•    Enclosures for drainage and water supply pipes should:

    be bounded by a compartment wall, floor, outside wall, intermediate floor or a casing

    have internal surfaces of Class 0 or Class B-s3, d2 or better

    not have an access panel which opens into a circulation space or bedroom

    be used only for drainage, or water supply, or vent pipes for a drainage system.

•    The casing should:

    be imperforate except for an opening for a pipe or an access panel

    not be of sheet metal

    have (including any access panel) not less than 30 minutes’ fire resistance.

•    The opening for a pipe should be as small as possible and fire-stopped around the pipe (see Figure 7.3.2)

•    Casing around a drainage system should have an integrity of 30 minutes.

•    A fire detection system may be required in an unoccupied part of the premises (e.g. a basement).

•    Where the basement storey contains a habitable room, either an external door or window suitable for egress from the basement or protected stairway leading to a final exit should be provided.

•    Special measures should be taken to prevent a basement fire endangering upper storeys.

•    An escape stair that forms part of the only escape route from an upper storey of a building it should not serve any basement storey.

•    The basement should be served by a separate stair.

•    If there is more than one escape stair from an upper storey of a building only one of the stairs needs to terminate at ground level.

•    Stairs may connect with the basement storey(s) if there is a protected lobby or corridor between the stair(s) and accommodation at each basement level.

•    In the case of small shop, office, industrial or other premises with no storey larger than 280m² and no more than two storeys plus a basement storey), the guidance in paragraph 3.323 should be followed.

•    In covered shopping complexes with premises in single occupancy no storey should have a floor area greater than 280m²

•    The premises should not comprise more than a basement, a ground floor and a first storey.

•    The maximum distance of travel between basement of first storey in small premises with a protected stair is 18m.

•    A single escape stair is permitted from a basement.

•    The width of an exit route from a stair which also forms the escape from the ground/basement storeys may need to be increased in accordance with the escape route.

•    Escape based on simultaneous evacuation should be used for all stairs serving basements.

•    Table 7.4.1 shows the capacity of stairs for basements and for simultaneous evacuation of the building.

•    In small single-storey non-residential buildings and annexes, the floor area of the building or annex should not exceed 36m².

•    Where the floor area of the building or annexe exceeds 10m², the walls should have a mass of not less than 130kg/m².

•    There is no surface mass limitation recommended for floor areas of 10m² or less.

•    Provide effective horizontal ties or effective anchorage of suspended floors in the following buildings:

    hotels not exceeding four storeys

    flats, apartments and other residential buildings not exceeding four storeys.

    offices not exceeding four storeys

    industrial buildings not exceeding three storeys

    retail premises not exceeding three storeys of less than 1000m² floor area in each storey

    single-storey educational buildings

    all buildings not exceeding two storeys to which the public are admitted and which contain floor areas not exceeding 2000m² at each storey.

•    A building containing an atrium passing through compartment floors may need special fire safety measures.

•    Guidance on suitable fire safety measures in these circumstances are in BS 5588-7.

•    A fire detection and fire alarm system should be installed in all new habitable rooms above the ground floor level, or in ground floor rooms where there is no final exit from the new room.

•    Smoke alarms should not be fixed over a stair or any other opening between floors.

•    The means of escape from a flat with a floor not more than 4.5m above ground level is relatively simple to provide.

•    A gallery should be provided with an alternative exit or, if the gallery floor is not more than 4.5m above ground level, an emergency egress should be provided.

•    Where the gallery floor is not provided with an alternative exit or escape window, it should comply with the following:

    the gallery should overlook at least 50 percent of the room below (see Diagram1)

    the distance between the foot of the access stair to the gallery and the door to the room containing the gallery should not exceed 3m

    the distance from the head of the access stair to any point on the gallery should not exceed 7.5m

    any cooking facilities within a room containing a gallery should either:

    be enclosed with fire-resisting construction; or

    be remote from the stair to the gallery and positioned such that they do not prejudice the escape from the gallery.

•    The bottom of the openable area of any window provided for emergency egress should be not more than 1100mm above the floor.

•    In a flat which has a floor at more than 4.5m above ground level one of the following approaches should be taken:

    provide a protected entrance hall which serves all habitable rooms, planned so that the travel distance from the entrance door to the door to any habitable room is 9m or less

    plan the flat so that the travel distance from the entrance door to any point in any of the habitable rooms does not exceed 9m and the cooking facilities are remote from the entrance door and do not prejudice the escape route from any point in the flat

    provide an alternative exit from the flat.

•    In a multistorey flat that does not have its own external entrance at ground level but has a floor at more than 4.5m above ground level, one of the following approaches should be taken:

    provide an alternative exit from each habitable room which is not on the flat entrance floor (see Figure 7.5.2a)

    provide one alternative exit from each floor (other than the entrance floor), with a protected landing entered directly from all the habitable rooms on that floor (see Figure 7.5.2b)

    provide a protected stairway plus additional smoke alarms in all habitable rooms and a heat alarm in any kitchen where the vertical distance between the floor of the entrance storey and the floors above and below it does not exceed 7.5m

    provide a protected stairway plus a sprinkler system (smoke alarms should also be provided).

•    Transfer grilles should not be fitted in any floor enclosing a protected stairway or entrance hall.

•    A single protected stair may be used, provided that the top floor of the building is no more than 11m above ground level and a high-level openable vent for fire and rescue service use is provided at each floor level.

•    In single-stair buildings, the smoke vents on the fire floor and at the head of the stair should be actuated by means of smoke detectors in the common access space providing access to the flats.

•    On detection of smoke in the common corridor/lobby, the vent(s) on the fire floor, the vent at the top of the smoke shaft and to the stairway should all open simultaneously.

•    If a building has a single access stair, that stair may be external if it serves a floor not more than 6m above ground level.

•    A single route is acceptable for parts of a floor from which a storey exit can be reached within the travel distance limit for travel in one direction set in Table 7.5.1.

•    When the number of occupants likely to use a room, tier or storey is not known, the capacity should be calculated on the basis of the appropriate floor space factors.

•    Escape routes should not be prejudiced by openings between floors, such as an escalator.

•    Where a ground floor storey exit shares a final exit with a stair via a ground floor lobby, the width of the final exit should be sufficient to enable a maximum evacuation flow rate equal to or greater than that from the storey exit and stair combined.

•    Where the number of people entering the lobby from the ground floor is more than 60 then the distance from the foot of the stair, or the storey exit, to the final exit should be a minimum of 2m.

•    Corridor partitions should be carried up to the soffit of the structural floor above, or to a suspended ceiling.

•    In covered shopping complexes, the size of small units that may be served by a single exit is further restricted (BS 5588-10).

•    The premises should be in a single occupancy and should not comprise more than a basement, a ground floor and a first storey.

•    No storey should have a floor area greater than 280m² (see Figure 7.5.3).

•    The floor areas should be generally undivided (except for kitchens, ancillary offices and stores) to ensure that exits are clearly visible from all parts of the floor areas.

•    Clear glazed areas should be provided in any partitioning separating a kitchen or ancillary office from an open floor area.

•    Where the maximum number of people who will use an escape stairs is unknown, the occupant capacity should be calculated on the basis of the appropriate floor space factors.

•    The escape stairs in a building designed for simultaneous evacuation should have the capacity to allow all floors to be evacuated simultaneously.

•    In phased evacuation, the first to be evacuated are all those of reduced mobility and those on the storey most immediately affected by the fire.

•    If there is a need to evacuate more people, it is done two floors at a time.

•    In a building designed on the basis of phased evacuation:

    every floor should be a compartment floor

    if any storey has a floor over 30m above ground level, the whole building should be protected by an automatic sprinkler system.

•    The minimum width of stair needed for phased evacuation is given in Section 7.10.

•    This assumes a phased evacuation of the fire floor first followed by evacuation of not more than two floors at a time.

•    Additional measures may be required if a protected stairway is also a protected shaft and it penetrates one or more compartment floors.

•    A stair in small premises may be open if it is a single stair if the floor area in any storey is less than 90m².

•    All doors on escape routes should have a swing that is clear of any change of floor level.

•    Every escape stair flight and landing that serves a floor level more than 18m above ground should be constructed of materials of limited combustibility.

•    The floorings of all escape routes (including the treads of steps and surfaces of ramps and landings) should be chosen to minimize their slipperiness when wet.

•    Any sloping floor should have a maximum pitch of 35° to the horizontal.

•    Lift entrances should be separated from the floor area on every storey by a protected lobby.

•    The upper surfaces of floors and stairs are not significantly involved in a fire until well developed and thus do not play an important part in fire spread in the early stages of a fire.

•    Parts of walls in rooms may be of a poorer performance than specified in the Approved Document provided the total area of those parts in any one room does not exceed one half of the floor area of the room; and subject to a maximum of 20m² in residential accommodation and 60m² in non-residential accommodation.

•    A suspended ceiling can contribute to the overall fire resistance of a floor/ceiling assembly.

•    Cavity barriers are needed in some concealed floor or roof spaces.

•    Elements of structure such as floor and gallery structures, should have at least the fire resistance given in Appendix A, Table A1.

•    The following floors are excluded from the definition of an element of structure:

    a roof that performs the function of a floor, such as for parking vehicles, or as a means of escape

    the lowest floor in a building

    a platform floor

    loading gallery, fly gallery, stage grid, lighting bridge, or any gallery provided for similar purposes or for maintenance and repair.

•    The normal provisions for fire resistance of elements of structure may be onerous if applied to the raised free-standing floors (such as those supported by racking).

•    A structure which does not have the appropriate fire resistance is acceptable provided the following conditions are satisfied:

•    the structure has only one tier and is used for storage purposes only

    the number of persons likely to be on the floor at any one time is low and does not include members of the public

    the floor is not more than 10m in either width or length and does not exceed one half of the floor area of the space in which it is situated

    the floor is open above and below to the room or space in which it is situated

    there is an appropriate means of escape.

•    Where an existing building is converted into flats, and has timber floors which are to be retained, the relevant provisions for fire resistance may be difficult to meet.

•    The spread of fire within a building can be restricted by compartmentation using walls and/or floors of fire-resisting construction.

•    The appropriate degree of subdivision depends on the height to the floor of the top storey in the building.

•    Subdivision is achieved using compartment walls and compartment floors.

•    Any floors bounding a protected shaft are considered to be compartment floors.

•    Parts of a building that are occupied mainly for different purposes should be separated from one another by compartment walls and/or compartment floors.

•    This does not apply where one of the different purposes is ancillary to the other.

•    Any floors in a place of special fire hazard should be a compartment floor.

•    In buildings containing flats, every floor should be a compartment floor.

•    Blocks of flats with a floor more than 30m above ground level should be fitted with a sprinkler system.

•    All floors in institutional buildings including healthcare should be constructed as compartment floors.

•    All floors in other residential buildings should be constructed as compartment floors.

•    The following should be constructed as compartment floors in non-residential buildings (i.e. office, shop and commercial, assembly and recreation, industrial, storage):

    every floor if the building has a storey with a floor at a height of more than 30m above ground level (see Table 7.5.4 and Figure 7.5.4).

    the floor of the ground storey if the building has one or more basements.

    the floor of every basement storey (except the lowest floor) if the building has a basement at a depth of more than 10m below ground level.

    every floor if the building forms part of a shopping complex.

    every floor if the building comprises shop and commercial, industrial or storage premises.

•    Every compartment floor should form a complete barrier to fire between the compartments they separate.

•    Every compartment floor should have the appropriate fire resistance shown in Table 7.5.3 and 7.5.4.

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

•    Where a compartment floor meets another compartment wall or an external wall, the junction should maintain the fire resistance of the compartmentation.

•    Fire-stopping should meet the provisions of paragraphs 10.17 to 10.19 of Approved Document B2.

•    At the junction of a compartment floor with an external wall that has no fire resistance the external wall should be restrained at floor level to reduce the movement of the wall away from the floor when exposed to fire.

•    Compartment walls should be able to accommodate the predicted deflection of the floor above by either:

    having a suitable head detail between the wall and the floor, that can deform but maintain integrity when exposed to a fire; or

    the wall may be designed to resist the additional vertical load from the floor above as it sags under fire conditions and thus maintain integrity.

•    Openings in compartment floors should be limited to those for:

    doors with the appropriate fire resistance which are fitted in accordance with the provisions of Approved Document B2 Appendix B

    the passage of pipes, ventilation ducts, service cables, chimneys, appliance ventilation ducts or ducts encasing one or more flue pipes

    refuse chutes of non-combustible construction

    atria designed in accordance with BS 5588-7

    protected shafts which meet the relevant provisions.

•    Any extension of a storey floor into a protected shaft should not compromise the free movement of air over the entire length of the shaft.

•    Cavity barriers should be provided at the junction between an external cavity wall and every compartment floor.

•    Cavity barriers should be provided at the junction between an internal cavity wall and every compartment floor.

•    The maximum dimensions of cavities do not apply to the cavities described below:

    any floor above a fire-resisting ceiling which extends throughout the building or compartment subject to a 30m limit on the extent of the cavity

    below a floor next to the ground or oversite concrete, if the cavity is less than 1000mm in height or if the cavity is not normally accessible by persons, unless there are openings in the floor such that it is possible for combustibles to accumulate in the cavity.

•    Where any single room with a ceiling cavity or underfloor service void exceeds the dimensions given in Table 7.5.5, cavity barriers should be provided on the line of the enclosing walls/ partitions of that room.

•    Pipes which pass through a fire-separating element should have a proprietary sealing system which has been shown by test to maintain the fire resistance of the floor.

•    Where sealing is not used then the nominal diameter of a pipe should conform with the requirements for dwellings in 6.5.2.

•    Enclosures for drains or water supply pipes should be bounded by a compartment floor, an outside wall, an intermediate floor, or a casing.

•    If a flue or duct passes through a compartment floor each wall of the flue or duct should have a fire resistance of at least half that of the floor in order to prevent the bypassing of the compartmentation.

•    In open-sided car park,s each storey should be naturally ventilated by permanent openings at each car parking level, having an aggregate vent area not less than 1/20 of the floor area at that level, of which at least half (1/40) should be equally provided between two opposing walls.

•    Any surface finish applied to a floor of the car park need not be non-combustible.

•    Car parks that are not open sided may have some, more limited, natural ventilation. Each storey should be ventilated by permanent openings which have an aggregate free vent area not less than 1/40 of the floor area at that level, of which at least half should be split equally and provided between two opposing walls (1/160 on each side).

•    Wet fire mains should be provided in buildings with a floor at more than 50m above fire and rescue service vehicle access level.

•    In lower buildings where fire mains are provided, either wet or dry mains are suitable.

•    Buildings with a floor at more than 18m above fire and rescue service vehicle access level, or with a basement at more than 10m below fire and rescue service vehicle access level, should be provided with firefighting shafts containing firefighting lifts (see Figure 7.5.5).

•    Smoke outlets, connected directly to the open air, should be provided from every basement storey, except for any basement storey that has:

    a floor area of not more than 200m².

    a floor not more than 3m below the adjacent ground level.

•    The combined clear cross-sectional area of all smoke outlets should not be less than 1/40 of the floor area of the storey they serve.

•    The amount of combustible material per unit of floor area will affect the standard of fire resistance specified.

•    The height of the top floor above ground will affect the ease of escape and of firefighting operations and the consequences should large scale collapse occur.

•    Most elements of structure in a single-storey building may not need fire resistance. However, fire resistance will be needed if the element:

    is part of (or supports) an external wall and there is provision to limit the extent of openings and other unprotected areas in the wall

    is part of (or supports) a compartment wall, including a wall common to two or more buildings

    supports a gallery.

•    The Target CO₂ Emission Rate (TER) is the minimum energy performance requirement for a new building and is expressed in terms of the mass of CO₂ emitted per year per square metre of the total useful floor area of the building.

•    The limiting standard for the properties of a floor is 0.25W/m²K.

•    Buildings with a total useful floor area greater than 1000m² should have automatic energy meter reading and data collection facilities.

•    Buildings with less than 500m² total useful floor area are exempt from the requirement to be pressure tested.

•    A factory-made modular building of less than 500m² floor area, with a planned service life of more than two years at more than one location, and where no site assembly work is needed other than making linkages between standard modules using standard link details, is exempt from the requirement to be pressure tested.

•    The concurrent notional U-value for a floor is 0.22W/m²K whether side-lit, top-lit or unlit.

•    Stand-alone buildings other than dwellings with a total useful floor area of less than 50m² are exempt from the energy efficiency requirements.

•    Conservatories or porches at ground level, where the floor area is less than 30m², are exempt from the energy efficiency requirements.

•    Where a proposed extension has a total useful floor area that is both greater than 100m², and greater than 25 percent of the total useful floor area of the existing building, the work should be regarded as a new building and the guidance in Approved Document L2A followed.

•    The requirement for consequential improvements, if appropriate, should also be met by following the guidance in Section 6 of Approved Document L2B.

•    Where a swimming pool is provided in a building, the U-value of the basin (walls and floor) should be no worse than 0.25W/m²K, as calculated according to BS EN ISO 133705.

•    Care should be taken to avoid thermal bridging, particularly around basin wall and floor junctions with foundations.

•    Where controlled services or fittings are being provided or extended if the area of openings in the newly created building is more than 25 percent of the total floor area, the area of openings should either be reduced to be not greater than 25 percent, or the larger area should be compensated for in some other way.

•    Work on fixed internal lighting is not notifiable if the floor area that is to be provided with new fixed lighting is not greater than 100m².

•    The work should still meet the standards set out in the compliance guide.

•    The U-value for new floors is 0.22W/m²K.

•    When upgrading thermal elements of floors:

    the threshold U-value of 0.70W/m²K

    the improved value of 0.25W/m²K.

•    Internal floor surfaces adjacent to the threshold of an accessible entrance should be made of materials that do not impede the movement of wheelchairs, e.g. not coir matting.

•    Changes in floor materials in accessible entrance should not create a potential trip hazard.

•    Where mat wells are provided, the surface of the mat should be level with the surface of the adjacent floor finish.

•    The floor surface in an entrance lobby should help to remove rainwater from shoes and wheelchairs.

•    Any manual controls for powered door systems should be located between 750mm and 1000mm above floor level.

•    Any reception desk or counter should be designed to accommodate both standing and seated visitors such that

•    at least one section of the counter is at least 1500mm wide, with its surface no higher than 760mm, and there is a knee recess, not less than 700mm, above floor level.

•    The floor surface in an entrance hall or reception area should be slip resistant.

•    In order to help people with visual impairment to appreciate the size of a space they have entered, or to find their way around, there should be a visual contrast between the wall and the ceiling, and between the wall and the floor.

•    In corridors:

    floors should be level or predominantly level (with a gradient no steeper than 1:60), with any section with a gradient of 1:20 or steeper designed as an internal ramp and in accordance with Table 7.5.6 and Figure 7.5.6

    where a section of the floor has a gradient, in the direction of travel, steeper than 1:60, but less steep than 1:20, it rises no more than 500mm without a level rest area at least 1500mm long (with a gradient no steeper than 1:60)

    any sloping section should extend the full width of the corridor or, if not, the exposed edge is clearly identified by visual contrast and, where necessary, protected by guarding

    floor surface finishes with patterns that could be mistaken for steps or changes of level should be avoided

    floor finishes should be slip resistant.

•    Junctions of floor surface materials at the entrance to the lobby area should not create a potential trip hazard.

•    In refreshment facilities, bars and counters all floor areas, even when located at different levels, should be accessible.

•    In refreshment facilities, changes in floor level are acceptable provided the different levels are accessible.

•    Part of the working surface of a bar or serving counter should be permanently accessible to wheelchair users, and at a level of not more than 850mm above the floor and, where necessary, part at a higher level for people standing.

•    The worktop of a shared refreshment facility (e.g. for tea making) should be at 850mm above the floor with a clear space beneath at least 700mm above the floor (see Figure 7.5.7).

•    A wheelchair-accessible threshold should be located at the transition between an external seating area and the interior of the facility.

•    In lifting devices and platforms:

    the landing call buttons are located between 900mm and 1100mm from the floor of the landing and at least 500mm from any return wall

    the floor of the lifting device should not be of a dark colour and should have frictional qualities similar to, or higher than, the floor of the landing.

•    In passenger lifts:

    car controls should be between 900mm and 1200mm above the car floor

    landing call buttons should be between 900mm and 1100mm from the landing floor.

•    People using or waiting for a lifting platform should have audible and visual information to tell them that the platform has arrived, and which floor it has reached.

•    In audience and spectator facilities the floor of each wheelchair space should be horizontal.

•    Wheelchair spaces at the back of a stepped terraced floor are provided in accordance with Figure 7.5.8 or 7.5.9 (the latter is best suited to entertainment buildings, such as cinemas).

•    In lecture/conference facilities, wheelchair users should have access to a podium or stage by means of a ramp or lifting platform.

•    There are exceptions to height requirements for some outlets, e.g. those set into the floor in open-plan offices.

•    Patterned walls in lecture/conference facilities, poor interior lighting or very bright natural backlighting should not have a detrimental effect on the ability of people to receive information from a sign language interpreter or a lip speaker.

•    Where a balcony is provided in a wheelchair-accessible bedroom, the door should have a level threshold and no horizontal transoms between 900mm and 1200mm above the floor.

•    Wall-mounted socket outlets etc. should be between 400mm and 1000mm above the floor.

•    Switches for permanently wired appliances should be between 400mm and 1200mm above the floor, unless needed at a higher level for particular appliances.

•    Switches or controls that require precise hand movements should be between 750mm and 1200mm above the floor.

•    Simple push button controls should not be more than 1200mm above the floor.

•    Pull cords for emergency alarm systems should be set at 100mm and another set between 800mm and 1000mm above the floor.

•    Floor, wall and ceiling surface materials should be chosen to help visually impaired people appreciate the boundaries of rooms or spaces and identify access routes.

•    The surface finish of sanitary fittings and grab bars should contrast visually with background wall and floor finishes

•    There should be visual contrast between wall and floor finishes.

•    Where the wall cladding is more than the height of two risers (or 380mm if not part of a stair), or as a vehicle barrier, then account should be taken of the additional imposed loading, as stipulated in Approved Document K.

•    External, internal load bearing and parapet walls must extend to the full storey height.

•    Walls should comply with BS EN 1996-2 and BSI Published Document PD 6697.

•    If a requirement of this part is considered too onerous, in a particular case it may be possible for a minor departure to be made.

    Judgement and experience, or calculation, may be used in respect of the aspect of the wall which is subject to the departure rather than for the entire wall.

•    BS EN 1996-1-1 gives design strengths for walls where the suitability for use of masonry units of other compressive strengths is being considered.

•    The single leaf of external walls of small single-storey non-residential buildings and annexes need be only 90mm thick, notwithstanding paragraphs 2C38 of Approved Document A (summarized below).

•    Walls of small single-storey non-residential buildings and annexes should be solidly constructed in brickwork or blockwork.

•    Where the floor area of the building or annexe exceeds 10m² the walls should have a mass of not less than 130kg/m².

•    One or two major openings not more than 2.1m in height are permitted in one wall of the building or annexe only.

•    Walls should have a minimum thickness of 90mm.

•    Walls which do not contain a major opening but exceed 2.5m in length or height should be bonded or tied to piers for their full height at not more than 3m centres (Figure 7.6.1a).

•    Walls with one or two major openings should in addition have piers as shown in Figures 7.6.1b and 7.6.1c.

•    Where ties are used to connect piers to walls they should be flat, 20mm x 3mm in cross section, in stainless steel, placed in pairs and be spaced at not more than 300mm centre vertically.

•    Walls should be tied horizontally at no more than 2m centres to the roof structure at eaves level, base of gables and along roof slopes as shown in Diagram 19 with straps fixed in accordance with paragraphs 2C35 and 2C36, summarized below.

•    Where straps cannot pass through a wall they should be adequately secured to the masonry using suitable fixings.

•    Wall ties should comply with BS EN 845-1 and should be material references 1 or 3 in BS EN 845-1 Table A1 austenitic stainless steel.

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

    clay bricks or blocks to BS EN 771-1

    calcium silicate bricks or blocks to BS EN 771-2

    concrete bricks or blocks to BS EN 771-3 or BS EN 771-4

    manufactured stone to BS EN 771-5.

    square dressed natural stone to the appropriate requirements described in BS EN 771-6.

•    Smoke alarms/detectors should be mounted at least 300mm from walls.

•    Units designed for wall-mounting may also be used provided that the units are above the level of doorways opening into the space.

•    Where an air circulation system circulates air only within an individual flat with an internal protected stairway or entrance hall, transfer grilles should not be fitted in any wall enclosing a protected stairway or entrance hall.

•    The wall between each flat and the corridor should be a compartment wall.

•    Smoke-control vents should be located on an external wall with minimum free area of 1.5m².

•    Storeys may be divided into two refuges by compartment wall.

•    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.

•    Loadbearing walls and compartment walls are treated as elements of structure although the latter are not necessarily loadbearing.

•    External walls, such as curtain walls or other forms of cladding which transmit only self-weight and wind loads and do not transmit floor load, are not regarded as loadbearing.

•    The enclosures (walls or partitions) of an inner room should be stopped at least 500mm below the ceiling.

•    A suitably sited vision panel not less than 0.1m² should be located in the door or wall of an inner room.

•    Progressive Horizontal Evacuation (PHE) in a care home requires those areas used for the care of residents to be subdivided into protected areas separated by compartment walls and compartment floors (see Figure 7.6.3)

•    Each storey, used for the care of residents, should be divided into at least three protected areas by compartment walls.

•    Where an external escape route is beside an external wall of the building, that part of the external wall within 1800mm of the escape route should be of fire-resisting construction, up to a height of 1100mm above the paving level of the route.

•    All walls, partitions and other enclosures that need to be fire-resisting to meet the provisions in this Approved Document (including roofs that form part of a means of escape) should have the appropriate performance given in Tables A1 and A2 of Appendix A.

•    If a protected stairway projects beyond, or is recessed from, or is in an internal angle of, the adjoining external wall of the building then the distance between any unprotected area in the external enclosures to the building and any unprotected area in the enclosure to the stairway should be at least 1800mm (see Figure 7.6.4).

•    Escape routes over flat roofs should be adequately defined and guarded by walls and/or protective barriers which meet the provisions in Approved Document K (Protection from falling, collision and impact).

•    Surface linings of walls should meet the requirements of Table 7.6.1.

•    When a classification includes ‘s3, d2’, this means that there is no limit set for smoke production and/or flaming droplets/particles.

•    Wall coverings which conform to BS EN 15102 (Decorative wallcoverings – roll and panel-form products), which achieve at least Class C-s3, d2 and are bonded to a Class A2-s3, d2 substrate, will also be acceptable.

•    For the purpose of the performance of wall linings, a wall includes:

    the surface of glazing (except glazing in doors)

    any part of a ceiling which slopes at an angle of more than 70° to the horizontal.

•    A wall does not include:

    doors and door frames

    window frames and frames in which glazing is fitted

    architraves, cover moulds, picture rails, skirtings and similar narrow members

    fireplace surrounds, mantle shelves and fitted furniture.

•    Parts of walls in rooms may be of a poorer performance than specified in the Approved Document but not poorer than Class 3 (National class) or Class D-s3, d2 (European class), provided the total area of those parts in any one room does not exceed one half of the floor area of the room; and subject to a maximum of 20m² in residential accommodation and 60m² in non-residential accommodation.

•    Any flexible membrane covering a structure (other than an air supported structure) should comply with the recommendations given in Appendix A of BS 7157.

•    Wall and ceiling surfaces exposed within the space above the suspended ceiling (other than the upper surfaces of the thermoplastic panels) should comply with the general provisions of paragraph 6.1 and Table 7.6.1, according to the type of space below the suspended ceiling.

•    Elements of structure such as structural frames, beams, columns, loadbearing walls (internal and external), floor structures and gallery structures should have at least the fire resistance given in Appendix A, Table A1.

•    A building should be subdivided into compartments separated from one another by walls and/or floors of fire-resisting construction.

•    Special forms of compartmentation to which particular construction provisions apply, are:

    walls common to two or more buildings

    walls dividing buildings into separated parts

    construction enclosing places of special fire hazard.

•    Any walls bounding a protected shaft are considered to be compartment walls.

•    A wall common to two or more buildings should be constructed as a compartment wall.

•    Parts of a building that are occupied mainly for different purposes should be separated from one another by compartment walls and/or compartment floors.

•    This does not apply where one of the different purposes is ancillary to the other.

•    In buildings containing flats, every wall separating a flat from any other part of the building should be constructed as compartment walls.

•    Every wall enclosing a refuse storage chamber should be constructed as a compartment wall.

•    The following walls should be constructed as compartment walls and compartment floors in buildings of a non-residential purpose group (i.e. office, shop and commercial, assembly and recreation, industrial, storage or other non-residential):

    every wall needed to sub divide the building to observe the size limits on compartments given in Table 7.6.2 (see Figure 7.6.5)

    in a shopping complex, every wall described in Section 5 of BS 5588-0 as requiring to be constructed to the standard for a compartment wall

    if the building comprises shop and commercial, industrial or storage premises, every wall provided to divide a building into separate occupancies, (i.e. spaces used by different organizations whether they fall within the same purpose group or not).

•    Every compartment wall should form a complete barrier to fire between the compartments they separate.

•    Every compartment wall should have the appropriate fire resistance indicated in Table 7.6.3.

•    Any part of an external wall which has less fire resistance than the appropriate amount given in Table 7.6.3 is considered to be an unprotected area.

•    Compartment walls that are common to two or more buildings should run the full height of the building in a continuous vertical plane.

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

•    Compartment walls used to form a separated part of a building should run the full height of the building in a continuous vertical plane.

•    The two separated parts can have different standards of fire resistance.

•    Compartment walls in a top storey beneath a roof should be continued through the roof.

•    Where a compartment wall meets another compartment wall or an external wall, the junction should maintain the fire resistance of the compartmentation.

•    At the junction of a compartment floor with an external wall that has no fire resistance (such as a curtain wall), the external wall should be restrained at floor level to reduce the movement of the wall away from the floor when exposed to fire.

•    Compartment walls should be able to accommodate the predicted deflection of the floor above by either:

    having a suitable head detail between the wall and the floor that can deform but maintain integrity when exposed to a fire; or

    designing the wall to resist the additional vertical load from the floor above as it sags under fire conditions and thus maintain integrity.

•    A compartment wall should be taken up to meet the underside of the roof covering or deck, with fire-stopping where necessary at the wall/roof junction.

•    The compartment wall should be continued across any eaves cavity.

•    To reduce the risk of fire spread over a roof, a zone of the roof 1500mm wide on either side of the wall should have a covering of designation AA, AB or AC on a substrate or deck of a material of limited combustibility, as set out in Figure 7.6.6 (a).

•    In buildings not more than 15m high, combustible boarding used as a substrate to the roof covering, wood wool slabs, or timber tiling battens, may be carried over the compartment wall provided that they are fully bedded in mortar or other suitable material over the width of the wall (see Figure 7.6.6(b)). This applies to, buildings or compartments in residential use (other than institutional), office buildings, assembly and recreation buildings.

•    As an alternative to paragraphs 8.29 or 8.30, the compartment wall may be extended up through the roof for a height of at least 375mm above the top surface of the adjoining roof covering.

•    Where there is a height difference of at least 375mm between two roofs or where the roof coverings on either side of the wall are AA, AB or AC, this height may be reduced to 200mm (see Figure 7.6.6 (c)).

•    Any openings in a compartment wall which is common to two or more buildings, or between different occupancies in the same building, should be limited to those for:

    a door which is needed to provide a means of escape in case of fire and which has the same fire resistance as the wall and is fitted in accordance Approved Document

    the passage of a pipe.

•    Openings in compartment walls (other than those described in paragraph 8.32) should be limited to those for:

    doors which have the appropriate fire resistance which are fitted in accordance with Approved Document B2 Appendix B

    the passage of pipes, ventilation ducts, service cables, chimneys, appliance ventilation ducts or ducts encasing one or more flue pipes

    refuse chutes of non-combustible construction

    atria designed in accordance with BS 5588-7

    protected shafts which meet the relevant provisions.

•    Cavity barriers should be provided at the junction between an external cavity wall and every compartment floor and compartment wall.

•    Cavity barriers should be provided at the junction between an internal cavity wall and every compartment floor, compartment wall, or other wall or door assembly which forms a fire-resisting barrier.

•    Any compartment wall should be carried up through a ceiling or roof cavity to maintain the standard of fire resistance.

•    You should not complete a line of compartmentation by fitting cavity barriers above them.

•    The provisions in Table 7.6.4 do not apply to any cavity described below:

    in a wall which should be fire-resisting only because it is loadbearing

    in a masonry or concrete external cavity wall shown in Figure 7.6.8

    formed behind the external skin of an external cladding system with a masonry or concrete inner leaf at least 75mm thick, or by overcladding an existing masonry (or concrete) external wall, provided that the cavity does not contain combustible insulation and the building is not put to a residential or institutional use.

•    Where any single room with a ceiling cavity or underfloor service void exceeds the dimensions given in Table 7.6.4, cavity barriers need only be provided on the line of the enclosing walls/partitions of that room, as long as:

    the cavity barriers are no more than 40m apart

    the surface of the material/product exposed in the cavity is Class 0 or Class 1 (National class) or Class C-s3, d2 or better (European class).

•    Cavity barriers in a stud wall or partition, or provided around openings may be formed of:

    steel at least 0.5mm thick

    timber at least 38mm thick

    polythene-sleeved mineral wool, or mineral wool slab, in either case under compression when installed in the cavity

    calcium silicate, cement-based or gypsum based boards at least 12mm thick.

•    No more than 25 percent of the length of a compartment wall should consist of door openings.

•    An external wall of a protected shaft does not need to have fire resistance.

•    Provisions for fire resistance of external walls of firefighting shafts and of external walls to protected stairways are contained in BS 5588-5.

•    Openings in other parts of the enclosure to a protected shaft should be limited to the following:

    If part of the enclosure to a protected shaft is a wall common to two or more buildings, only the following openings should be made in that wall:

    a door which provides a means of escape in case of fire and has the same fire resistance as that required for the wall

    the passage of a pipe.

    Other parts of the enclosure should only have openings for:

    doors which have the appropriate fire resistance

    the passage of pipes

    inlets to, outlets from and openings for a ventilation duct, (if the shaft contains or serves as a ventilating duct)

    the passage of lift cables into a lift machine room (if the shaft contains a lift)

    if the machine room is at the bottom of the shaft, the openings should be as small as practicable.

•    External walls of the building should have sufficient fire resistance to prevent fire spread across the boundary.

•    The provisions are closely linked with those for space separation (Section 13 of Approved Document B3 (below)).

•    The limits depend on the distance of the wall from the relevant boundary.

•    Some or all of the walls may have no fire resistance (unless they are loadbearing).

•    The relevant period of fire resistance for external walls depends on the use, height and size of the building concerned.

•    If the wall is 1000mm or more from the relevant boundary, a reduced standard of fire resistance is accepted in most cases and the wall only needs fire resistance from the inside.

•    The combustibility of external walls of buildings that are less than 1000mm from the boundary and the external walls of high buildings and those of the assembly and recreation purpose groups should be restricted.

•    The surface’s susceptibility to ignition from an external source should be reduced.

•    Internal and external loadbearing walls should maintain their loadbearing function in the event of fire.

•    The external walls of the building should have the appropriate fire resistance given in Table 7.6.3 (unless they are an unprotected area).

•    Where a portal-framed building is near a relevant boundary, the external wall near the boundary may need fire resistance to restrict the spread of fire between buildings.

•    Where the external wall of the building cannot be wholly unprotected, the rafter members of the frame, as well as the column members, may need to be fire protected.

•    The external envelope should not provide a medium for fire spread if it is likely to be a risk to health or safety.

•    External walls should either meet the guidance given in paragraphs 12.6 to 12.9 (below) or meet the performance criteria given in the BRE Report (BR 135).

•    The total amount of combustible material may also be limited in practice by the provisions for space separation.

•    The external surfaces of walls should comply with Figure 7.6.10.

•    Where a mixed-use building includes assembly and recreation purpose group(s) accommodation, the external surfaces of walls should meet the requirements of Figure 7.6.10.

•    In a building with a storey 18m or more above ground level, any insulation product, filler material (not including gaskets, sealants and similar) used in the external wall construction should be of limited combustibility.

•    This restriction does not apply to masonry cavity wall which complies with Figure 7.6.6.

•    Cavity barriers should be provided.

•    If an external wall of a building where Table 7.6.4 does not apply, the maximum dimensions of cavities and the surfaces which face into cavities should meet the requirements in Figure 7.6.8.

•    A wall is considered to face a boundary if it makes an angle with it of 80° or less (see Figure 7.6.9).

•    The boundary which a wall faces, whether it is the actual boundary of the site or a notional boundary, is called the relevant boundary (see Figure 7.6.9, 7.6.10)

•    Any part of an external wall of a stairway in a protected shaft is excluded from the assessment of unprotected area.

•    If an external wall has the appropriate fire resistance, but has combustible material more than 1mm thick as its external surface, then that wall is counted as an unprotected area amounting to half the actual area of the combustible material (see Figure 7.6.11).

•    A material with a Class 0 rating (National class) or Class B-s3, d2 rating (European class) (see Appendix A, paragraphs 7 and 13) need not be counted as unprotected area.

•    Any part of an external wall of a stairway in a protected shaft is excluded from the assessment of unprotected area.

•    If an external wall has the appropriate fire resistance, but has combustible material more than 1mm thick as its external surface, then that wall is counted as an unprotected area amounting to half the actual area of the combustible materia (see Figure 7.6.11). (A material with a Class 0 rating (National class) or Class B-s3, d2 rating (European class) need not be counted as unprotected area).

•    Small unprotected areas in an otherwise protected area of wall are considered to pose a negligible risk of fire spread and may be disregarded.

•    Figure 7.6.12 shows the constraints that apply to the placing of such areas in relation to each other and to lines of compartmentation inside the building.

•    These constraints vary according to the size of each unprotected area.

•    Parts of the external wall of an uncompartmented building which are more than 30m above mean ground level, may be disregarded (see Figure 7.6.14).

•    A wall within 1000mm from any point on the relevant boundary (including a wall coincident with the boundary) will meet the provisions for space separation if:

    the only unprotected areas are those in Figure 7.6.14 or referred to in paragraph 13.12

    the rest of the wall is fire-resisting from both sides.

•    A wall at least 1000mm from any point on the relevant boundary will meet the provisions for space separation if:

    the extent of unprotected area does not exceed that discussed in paragraph 13.15

    the rest of the wall (if any) is fire-resisting from the inside of the building.

•    There are two methods for calculating the acceptable amount of unprotected area in an external wall that is at least 1000mm from any point on the relevant boundary.

    Method 1: used for small residential buildings which do not belong to purpose group 2a (institutional type premises).

    Method 2: used for most buildings or compartments where Method 1 is not appropriate.

•    Method 1 applies only to a building intended to be used for block of flats or other residential purposes (not institutional), which is 1000mm or more from any point on the relevant boundary.

•    To determine the maximum unprotected area:

    the building should not exceed three storeys high (excluding basements)

    the building should not be more than 24m in length

    on each side of the building:

    the distance of the side of the building from the relevant boundary; and

    the extent of the unprotected area should be within the limits in Figure 7.6.13

    Any parts of the side of the building in excess of the maximum unprotected area should be fire-resisting

•    Method 2 applies to buildings or compartments for any use and which is not less than 1000mm from any point on the relevant boundary.

    The building or compartment should not exceed 10m in height except for an open-sided car park in Purpose Group 7(b).

    Each side of the building meets the provisions for space separation by:

    the distance of the side of the building from the relevant boundary; and

    the extent of unprotected area, are within the appropriate limits given in Table 7.6.6 of Approved Document B2.

    any parts of the side of the building in excess of the maximum unprotected area should be fire-resisting.

•    If the roof passes over the top of a compartment wall polycarbonate and PVC rooflights with a Class 1 rating may be regarded as having an AA designation.

•    Natural smoke outlets should be at high level in the ceiling or wall of the space they serve.

•    Flame spread over wall surfaces is controlled by providing for the lining materials which meet performance levels in tests appropriate to the materials or products involved.

•    A thermoplastic material in isolation cannot be assumed to protect a substrate, when used as a lining to a wall.

•    Most elements of structure in a single-storey building may not need fire resistance.

•    Fire resistance will be needed if the element:

    is part of (or supports) an external wall and there is provision to limit the extent of openings and other unprotected areas in the wall

    is part of (or supports) a compartment wall, including a wall common to two or more buildings

    supports a gallery.

•    The limiting standard for the properties of a wall is 0.35W/m²K.

•    Where a swimming pool is being provided in a building, the U-value of the basin (walls and floor) should be no worse than 0.25W/m²K, as calculated according to BS EN ISO 133705.

•    Care should be taken to avoid thermal bridging, particularly around basin wall and floor junctions with foundations.

•    The concurrent notional U-value for a wall is 0.26W/m²K, whether side-lit, top-lit or unlit.

•    New buildings other than dwellings which are roofed constructions having walls and which use energy to condition the indoor climate must comply with the energy efficiency requirements unless they are exempt.

•    A building means the whole of a building or parts of a building designed or altered to be used separately.

•    The following new buildings or parts of new buildings other than dwellings are exempt:

    buildings which are used primarily or solely as places of worship

    temporary buildings with a planned time of use of two years or less, industrial sites, workshops, non-residential agricultural buildings with low energy demand

    stand-alone buildings other than dwellings with a total useful floor area of less than 50m²

    car ports, covered yards, covered ways and some conservatories or porches attached to existing buildings.

•    Building work in most existing buildings other than dwellings will need to comply with the energy efficiency requirements of the Building Regulations.

•    The following classes of buildings are exempt from this requirement:

    buildings which are:

    listed

    in a conservation area

    included in the schedule of monuments

    where compliance with the energy efficiency requirements would unacceptably alter their character or appearance

•    Special considerations apply to:

    historic buildings and buildings used primarily or solely as places of worship

    buildings with low energy demand

    modular and portable buildings.

•    Any changes to the building fabric or fixed building services should comply with Approved Document L2B.

•    The exemption for conservatory and porch extensions only applies where the existing walls, doors and windows which separate the conservatory from the building are retained or, if removed, are replaced by walls, windows and doors which meet the energy efficiency requirements.

•    Where a conservatory or porch is not exempt from the energy efficiency requirements then reasonable provision would be to provide effective thermal separation between the heated area in the existing building, i.e. the walls, doors and windows between the building and the extension should be insulated and draughtproofed to at least the same extent as in the existing building.

•    The overall U-value of curtain walling should be no greater than the better of 1.8W/m²K or a limiting U-value U_limit given by:

U_limit = 0.8+ [{1.2+ (FOL x 0.5)} × GF]

•    The U-value for new walls is 0.28W/m²K.

•    To avoid the air barrier and the insulation layer being not contiguous, either the insulation layer should be contiguous with the air barrier at all points in the building envelope, or the space between them should be filled with solid material such as in a masonry wall.

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

•    When assessing whether the area proportion constitutes a major renovation of a building, the surface area of the whole of the external building envelope should be taken into account i.e. external walls, floor, roof, windows, doors, roof windows and rooflights.

•    When upgrading thermal elements:

    Walls with cavity insulation should have:

    a threshold U-value of 0.70W/m²K

    an improved value of 0.55W/m²K.

    Walls with external or internal insulation should have:

    a threshold U-value of 0.70W/m²K

    an improved value of 0.30W/m²K.

•    A ramped access should have a surface width between walls, upstands etc. of at least 1.5m.

•    A stepped access should have flights with a surface width between enclosing walls, strings or upstands of not less than 1.2m.

•    Handrails should be spaced away from the wall and rigidly supported in a way that avoids impeding finger grip.

•    There should be a clearance of between 50 and 75mm between the handrail and any adjacent wall surface.

•    A space alongside the leading edge of a door should be provided to enable a wheelchair user to reach and grip the door handle, then open the door without releasing hold on the handle and without the footrest colliding with the return wall.

•    Manually operated non-powered entrance doors should have an opening force at the leading edge of the door of not more than 30N at the leading edge from 0° (the door in the closed position) to 30° open, and not more than 22.5N at the leading edge from 30° to 60° of the opening cycle.

•    Manually operated non-powered entrance doors should have an unobstructed space of at least 300mm on the pull side of the door between the leading edge of the door and any return wall.

•    Glazed screens in front of the reception point, or light sources or reflective wall surfaces, should not compromise the ability of a person with a hearing impairment to lip read or follow sign language.

•    Internal doors should have:

    an unobstructed space of at least 300mm on the pull side of the door between the leading edge of the door and any return wall, unless the door has power-controlled opening or it provides access to a standard hotel bedroom.

    door frames that contrast visually with the surrounding wall

    glass or fully glazed doors that are clearly differentiated from any adjacent glazed wall or partition by the provision of a high-contrast strip at the top and on both sides.

•    In order to help people with visual impairment to appreciate the size of a space they have entered, or to find their way around, there should be a visual contrast between the wall and the ceiling, and between the wall and the floor.

•    Landing call buttons should be located between 900mm and 1100mm from the floor of the landing and at least 500mm from any return wall.

•    Handrails should be provided on at least one wall of the lifting device with its top surface at 900mm (nominal) above the floor and located so that it does not obstruct the controls or the mirror.

•    The use of visually and acoustically reflective wall surfaces should be avoided.

•    Passenger lift car controls should be located between 900mm and 1200mm (preferably 1100mm) from the car floor and at least 400mm from any return wall.

•    Landing call buttons are located between 900mm and 1100mm from the floor of the landing and at least 500mm from any return wall.

•    Lift landing and car doors should be distinguishable visually from the adjoining walls.

•    The use of visually and acoustically reflective wall surfaces should be minimized within the lifting platform to prevent discomfort for people with visual and hearing impairment.

•    Lifting platform controls should be located between 800mm and 1100mm from the floor of the lifting platform and at least 400mm from any return wall.

•    Landing call buttons should be located between 900mm and 1100mm from the floor of the landing and at least 500mm from any return wall.

•    Doors should be distinguishable visually from the adjoining walls.

•    Walls in lecture/conference facilities should not have a detrimental effect on the ability of people to receive information from a sign language interpreter or a lip speaker.

•    Wall-mounted socket outlets, telephone points and TV sockets should be between 400mm and 1000mm above the floor (preferably at the lower end of the range).

•    Switches for permanently wired appliances should be between 400mm and 1200mm above the floor, unless needed at a higher level for particular appliances.

•    All switches and controls that require precise hand movements should be between 750mm and 1200mm above the floor.

•    Simple push button controls should not be more than 1200mm above the floor.

•    The appropriate choice of wall surface materials and finishes should help visually impaired people appreciate the boundaries of rooms or spaces, identify access routes and receive information.

•    The surface finish of sanitary fittings and grab bars should contrast visually with background wall finishes.

•    There should be visual contrast between wall and floor finishes.

•    The transfer space in unisex wheelchair accessible toilets should be kept clear to the back wall.

•    In unisex wheelchair accessible toilets, where the horizontal support rail on the wall adjacent to the WC is set with the minimum spacing from the wall, an additional drop-down rail is provided on the wall side at a distance of 320mm from the centre line of the WC.

•    Where the horizontal support rail on the wall adjacent to the WC is set so that its centre line is 400mm from the centre line of the WC, there is no additional drop-down rail.

•    In WC compartments within separate-sex toilet washrooms, there should be a 450mm diameter manoeuvring space between the swing of the door, the WC pan and the side wall of the compartment.

•    There should be a vertical grab bar on the rear wall and space for a shelf and fold-down changing table.

•    Wheelchair-accessible changing and shower facilities should be provided with wall-mounted drop-down support rails and wall-mounted slip-resistant tip-up seats (not spring loaded).

•    Smoke alarms/detectors that are ceiling-mounted should be at least 300mm from walls and light fittings.

•    The sensor in ceiling-mounted devices should be between 25mm and 600mm below the ceiling (25 to 150mm in the case of heat detectors or heat alarms).

•    The enclosures of an inner room should be stopped at least 500mm below the ceiling.

•    The partitions in a means of escape should be carried up to the soffit of the structural floor above, or to a suspended ceiling.

•    The potential for smoke to bypass the subdivision in a corridor should be restricted by enclosing the cavity on the lower side by a fire-resisting ceiling which extends throughout the building, compartment or separated part.

•    The choice of materials for 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.

•    Subject to the variations and specific provisions described in paragraphs 6.2 to 6.16 of Approved Document B Volume 2 (below), the surface linings of ceilings should meet the classifications in Table 7.7.1.

•    For the purposes of the performance of ceiling linings, a ceiling includes:

    the surface of glazing

    any part of a wall which slopes at an angle of 70° or less to the horizontal

    the underside of a mezzanine or gallery

    the underside of a roof exposed to the room below.

•    A ceiling does not include:

    trap doors and their frames

    the frames of windows or roof lights

    architraves, cover moulds, picture rails, exposed beams and similar narrow members.

•    A suspended ceiling can contribute to the overall fire resistance of a floor/ceiling assembly.

•    Such a ceiling should satisfy paragraph 6.1 of Approved Document B Volume 2 (above).

•    It should also meet the provisions of Table 7.7.1 and Table 7.7.2.

•    The need for cavity barriers in concealed floor or roof spaces can be reduced by the use of a fire-resisting ceiling below the cavity.

•    Such a ceiling should comply with Figure 7.7.1.

•    Thermoplastic materials which cannot meet the performance given in Table 7.7.1 can be used in windows, rooflights and lighting diffusers in suspended ceilings if they comply with the provisions described in paragraphs 6.13 to 6.15 of Approved Document B Volume 2 (below).

•    Flexible thermoplastic material may be used in panels to form a suspended ceiling if it complies with the guidance in paragraph 6.16 of Approved Document B Volume 2 (below).

•    Lighting diffusers which form part of a ceiling and are not concerned with diffusers of light fittings which are attached to the soffit of, or suspended beneath, a ceiling are not subject to this requirement.

•    Lighting diffusers are translucent or open structured elements that allow light to pass may be part of a luminaire or used below rooflights or other sources of light.

•    Thermoplastic lighting diffusers should not be used in fire-protecting or fire-resisting ceilings, unless they have been satisfactorily tested as part of the ceiling system that is to be used to provide the appropriate fire protection.

•    Ceilings to rooms and circulation spaces (but not protected stairways) may incorporate thermoplastic lighting diffusers if the following provisions are observed:

    wall and ceiling surfaces exposed within the space above the suspended ceiling should comply with paragraph 6.1 (above) and Table 7.7.1 according to the type of space below the suspended ceiling

    TP(a) (rigid) diffusers may be used with no restrictions.

    TP(b) or Class 3 diffusers should be limited in extent as follows:

    the maximum area of each diffuser panel or rooflight must not exceed 5m²

    the minimum separation between diffuser panels and rooflights should be 3m

    the maximum total area or diffuser panels and rooflights as percentage of the floor area of the space shall not exceed:

    50 percent in rooms

    15 percent in circulation spaces.

•    The ceiling of a room may be constructed either as a suspended or as a stretched skin membrane from panels of a thermoplastic material of the TP(a) flexible classification, provided that it is not part of a fire-resisting ceiling.

•    Each panel should not exceed 5m² in area and should be supported on all its sides.

•    Transfer grilles should not be fitted in any wall, door, floor or ceiling enclosing a protected stairway or entrance hall.

•    The shaft of a vent should extend at least 2.5m above the ceiling of the highest storey served by the shaft.

•    Extract ventilators should be located as high as practicable and preferably not less than 400mm below the ceiling level.

•    PSVs should be located in the ceiling of a room.

•    New thermal elements in a pitched roof insulation at ceiling level should be 0.16W/m²K.

•    Upgraded thermal elements in a pitched roof insulation at ceiling level should have a threshold U-value of 0.35W/m²K and an improved U-value of 0.16W/m²K.

•    In order to help people with visual impairment to appreciate the size of a space they have entered, or to find their way around, there should be a visual contrast between the wall and the ceiling.

•    Attention to surface finishes should be coupled with good natural and artificial lighting design.

•    Straps should be fixed using one of the following methods:

    Walls should be strapped to floors above ground level, at intervals not exceeding 2m as shown in Figure 7.8.2, by tension straps conforming to BS EN 845-1.

    The tension straps should be material reference 14 or 16.1 or 16.2 (galvanised steel) or other more resistant specifications.

    The declared tensile strength of tension straps should not be less than 8kN.

    Tension straps need not be provided:

    when a concrete floor has at least 90mm bearing on the supported wall

    where floors are at or about the same level on each side of a supported wall, and contact between the floors and wall is either at 2m intervals or continuous

    where contact is intermittent, the points of contact should be in line or nearly in line on plan.

•    Gable walls should be strapped to roofs by tension straps (Figure 7.8.3) as described above.

•    Vertical strapping at least 1m in length should be provided at eaves level at intervals not exceeding 2m.

•    Vertical strapping may be omitted if the roof:

    has a pitch of 15° or more

    is tiled or slated

    is of a type known by local experience to be resistant to wind gusts

    has main timber members spanning onto the supported wall at not more than 1.2m centres.

•    Portal frames are often used in single-storey industrial and commercial buildings where there may be no need for fire resistance of the structure.

•    It is considered technically and economically feasible to design the foundation and its connection to the portal frame so that it would transmit the overturning moment caused by the collapse, in a fire, of unprotected rafters, purlins and some roof cladding, while allowing the external wall to continue to perform its structural function.

•    In a portal framed building there should be some form of roof venting to give early heat release.

•    A ceiling includes the underside of a roof exposed to the room below but does not include the frames of rooflights.

•    Cavity barriers are required in some concealed roof spaces; this requirement can be reduced by the use of a fire-resisting ceiling below the cavity.

•    If more than one escape route is available from a storey, or part of a building, one of those routes may be by way of a flat roof provided that it complies with the provisions:

    the roof should be part of the same building from which escape is being made

    the route across the roof should lead to a storey exit or external escape route

    the part of the roof forming the escape route and its supporting structure, together with any opening within 3m of the escape route, should be fire-resisting.

    the route should be adequately defined and guarded by walls and/or protective barriers which meet the provisions in Approved Document K (Protection from falling, collision and impact).

•    It is not permitted for an escape route from an institutional building, or part of a building intended for use by members of the public to be by way of a flat roof.

•    Where more than one escape route is available from a storey, some of the escape routes from that storey may be by way of an external escape stair (provided that there is at least one internal escape stair from every part of each storey).

•    The external stair should serve a floor not more than 6m above a roof or podium which is itself served by an independent protected stairway.

•    An area in the open air such as a flat roof which is sufficiently protected (or remote) from any fire risk and provided with its own means of escape is a satisfactory refuge.

•    Roofs that form part of an escape should have a minimum of 30 minutes fire resistance.

•    A stair connecting ground floor or paving level with a flat roof not more than 6m above or below ground level is not required to be constructed of materials of limited combustibility.

•    Mechanical ventilation exhaust points should be away from combustible roofing materials.

•    Rooftop plant should have the following maximum travel distances:

    escape route not in open air in one direction 18m

    escape route not in open air in more than one direction 45m

    escape route in open air in one direction 60m

    escape route in open air in more than one direction 100m.

•    Plastic rooflights with at least a Class 3 rating may be used provided the limitations in Table 7.8.1, Figure 7.8.4 and Figure 7.8.5 are observed.

•    Guidance on the use of PTFE-based materials for tension-membrane roofs is given in a BRE report Fire Safety of PTFE-Based Materials Used in Buildings (BR 274, BRE 1994).

•    Thermoplastic materials can be used in rooflights in suspended ceilings.

•    Rooflights to rooms and circulation spaces (with the exception of protected stairways) may be constructed of a thermoplastic material if:

    the lower surface has a TP(a) (rigid) or TP(b) classification

    the size and disposition of the rooflights accords with the limits in Table 7.8.1 and the guidance in B4 to Approved Document B2.

•    Lighting diffusers may be part of a luminaire or used below rooflights.

•    Roofs are not treated as elements of structure unless they serve the function of a floor.

•    Compartment walls in a top storey beneath a roof should be continued through the roof space.

•    A compartment wall should meet the underside of the roof covering with fire-stopping at the wall/ roof junction where necessary (see Figure 7.8.6).

•    A zone of the roof 1500mm wide on either side of the wall should have a covering of designation AA, AB or AC on a substrate or deck of a material of limited combustibility (see Figure 7.8.6)

•    Combustible boarding used as a substrate to the roof covering, wood wool slabs, or timber tiling battens, may be carried over the compartment wall provided that they are fully bedded in mortar or other suitable material over the width of the wall in the following buildings:

    buildings or compartments in residential use (not institutional)

    office buildings

    assembly and recreation buildings (see Figure 7.8.6).

•    A compartment wall may be extended up through the roof for a height of at least 375mm above the top surface of the adjoining roof covering (see Figure 7.8.6)

•    Where there is a height difference of at least 375mm between two roofs, or where the roof coverings on either side of the wall are AA, AB or AC, this height may be reduced to 200mm.

•    A compartment wall should carry on up through a ceiling or roof cavity to maintain the standard of fire resistance.

•    A cavity that exists above or below any fire-resisting construction on an escape route should either be:

    fitted with cavity barriers on the line of the enclosure to the protected escape route; or

    enclosed on the lower side by a fire-resisting ceiling which extends throughout the building/ compartment.

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

    both surfaces of the insulating layer have a surface spread of flame of at least Class 0 or 1 (National class) or Class Cs3, d2 or better (European class)

    both surfaces make contact with the inner and outer skins of cladding (see Figure 7.8.7).

•    In institutional and other residential buildings, a cavity that exists above or below partitions between bedrooms because the enclosures are not carried to full storey height, or, (in the case of the top storey) to the underside of the roof covering, should either be:

    fitted with cavity barriers on the line of the partitions

    (cavities above the partitions) enclosed on the lower side by a fire-resisting ceiling which extends throughout the building, compartment or separated part.

•    Cavity barriers should be used to sub divide any cavity, including any roof space, so that the distance between cavity barriers does not exceed the dimensions given in Table 7.8.2.

•    Table 7.8.2 sets out maximum dimensions for undivided concealed spaces.

•    Extensive concealed spaces should be subdivided to comply with the dimensions given.

•    Table 7.8.2 does not apply to any cavity described below:

    any floor or roof cavity above a fire-resisting ceiling which extends throughout the building or compartment, subject to a 30m limit on the extent of the cavity

    by over cladding an existing concrete roof, provided that the cavity does not contain combustible insulation and the building is not put to a residential or institutional use

    between double-skinned corrugated or profiled insulated roof sheeting, if the sheeting is a material of limited combustibility and both surfaces of the insulating layer have a surface spread of flame of at least Class 0 or 1 (National class) or Class C-s3, d2 or better (European class) and make contact with the inner and outer skins of cladding (see Figure 7.8.7).

•    Any surface finish applied to a roof of a car park, or within any adjoining building, compartment or separated part to the structure enclosing the car park need not be made of non-combustible material if the finish meets the guidance in Approved Document B2.

•    The roof of the building shall adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building.

•    In existing portal framed buildings there may be some form of roof venting to give early heat release. (e.g. PVC rooflights covering some 10 percent of the floor area and evenly spaced over the floor area.)

•    A roof is not subject to the requirements on space separation unless it is pitched at an angle greater than 70° to the horizontal.

•    Vertical parts of a pitched roof such as dormer windows would not need to meet the provisions unless the slope of the roof exceeds 70°.

•    It is a matter of judgement whether a continuous run of dormer windows occupying most of a steeply pitched roof should be treated as a wall rather than a roof.

•    Roof coverings near a boundary should protect against the spread of fire over the boundary.

•    Roof coverings may consist of one or more layers of material but does not refer to the roof structure as a whole.

•    Fire properties of roofs should meet the requirements of Tables 6.8.3 and 6.8.4.

•    The size and disposition of rooflights should accord with the limits in Table 7.8.5 and with the guidance in Tables 7.8.6 and 7.8.7.

•    Table 7.8.6 sets out the limitations on the use of plastic rooflights which have at least a Class 3 (National class) or Class D-s3, d2 (European class) lower surface.

•    When used in rooflights, a rigid thermoplastic sheet product made from polycarbonate or from unplasticised PVC, which achieves a Class 1 (National class) rating for surface spread of flame can be regarded as having an AA (National class) designation or B_ROOF(t4) (European class) classification, other than for the purposes of Figure 7.8.6.

•    Table 7.8.7 sets out the limitations on the use of thermoplastic materials with a TP(a) rigid or TP(b) classification (see also Figure 7.8.8).

•    Surrounding roof covering should be a material of limited combustibility for at least 3m distance.

•    Rooflights should be at least 1500mm from the compartment wall.

•    The method of classifying thermoplastic materials is given in Appendix A to Approved Document B2.

•    Test methods for roof coverings are specified in BS 476-3: or BS EN 13501-5.

•    The notional performance of some common roof coverings is given in Table 7.8.8.

•    Rooflights are controlled on a similar basis to plastic rooflights

•    The separation distance is the minimum distance from the roof to the relevant boundary.

•    Table 7.8.9 sets out separation distances according to the type of roof covering and the size and use of the building.

    There are no restrictions on the use of roof coverings designated AA, AB or AC (National class) or B_ROOF (t4) (European class) classification.

    Roof covering products defined in Commission Decision 2000/553/EC of 6September 2000 implementing Council Directive 89/106/EEC can be used without restriction.

•    When used in rooflights, unwired glass at least 4mm thick can be regarded as having an AA designation (National class) designation or B_ROOF(t4) (European class) classification.

•    Thatch and wood shingles should be regarded as having an AD/BD/CD designation or E_ROOF(t4) (European class) classification in Table 7.8.8 if their performance cannot be established.

•    Provision shall be made for any windows, skylights ceilings or roofs to be safely accessible for cleaning.

•    Windows, skylights and ventilators which can be opened by people in or about the building shall be so constructed or equipped that they may be opened, closed or adjusted safely.

•    Work in historic buildings that warrants sympathetic treatment, and where advice from others could be beneficial, includes restoring the historic character of a building that has been subject to previous inappropriate alteration, e.g. replacement rooflights.

•    Installation of thermal insulation in a roof space or loft space is not notifiable as long as this is the only work carried out and the work is carried out voluntarily and not in order to comply with any requirement in the Building Regulations.

•    A proposed extension should incorporate roof windows/rooflights that meet the standards.

•    The area of windows and rooflights in an extension should generally not exceed the following values:

    Residential buildings – 20 percent of the roof area

    Places of assembly, offices and shops – 20 percent of the roof area

    Industrial and storage buildings – 20 percent of the roof area

    Vehicle access doors and display windows and similar glazing – not applicable

    Smoke vents – as required.

•    If an existing roof window or rooflight which separates a conditioned space from an unconditioned space or the external environment has a U-value that is worse than 3.3W/m²K, the guidance in paragraphs 4.23 to 4.28 of Approved Document L2B (below) should be followed.

•    The application of the term controlled fitting to a roof window or rooflight refers to a whole unit, i.e. including the frame.

•    Replacing the glazing while retaining an existing frame is not providing a controlled fitting, and so such work is not notifiable.

•    Where roof windows or rooflights are to be provided, reasonable provision in normal cases would be the installation of draughtproofed units whose performance is no worse than:

    roof ventilators (including smoke extract ventilation) U-value of 3.5W/m²K

    roof windows and rooflights U-value of 1.8 W/m²K for the whole unit.

•    If a rooflight is enlarged or a new one created, the area of the windows and pedestrian doors and of rooflights expressed as a percentage of the total floor area of the building should not exceed 20 percent or should be compensated for in some other way.

•    U-values of windows, roof windows, rooflights and doors are calculated using the methods and conventions set out in BRE Report BR 4436, and should be based on the whole unit.

•    The U-values for roof windows and rooflights given in Table 7.8.10 are based on the U-value having been assessed in the vertical position.

•    If a particular unit has been assessed in a plane other than the vertical, the standards given in the Approved Document should be adjusted following the guidance given in BR 443.

•    In certain classes of building with high internal gains, a less demanding U-value for glazing may be an appropriate way of reducing overall CO₂ emissions.

•    If this case can be made the average U-value for rooflights can be relaxed from the values given above (4.24) but the value should not exceed 2.7W/m²K.

•    Replacing existing roof windows or rooflights which have a U-value worse than 3.3W/m²K following the guidance in paragraphs 4.23 to 4.28 (above) is considered to be practical and economically feasible in ordinary circumstances.

•    Where the installed capacity per unit area of a heating system is increased existing roof windows or rooflights within the area served and which have U-values worse than 3.3W/m²K should be replaced following the guidance in paragraphs 4.23 to 4.28 (above).

•    Where the installed capacity per unit area of a cooling system is increased and the area of windows and roof windows within the area served exceeds 40 percent of the façade area, or the area of rooflights exceeds 20 percent of the area of the roof and the design solar load exceeds 25W/m²K, then the solar control provisions should be upgraded.

•    In existing buildings the Target CO₂ Emission Rate (TER) is based on a building of the same size and shape as the actual building, constructed to a concurrent specification.

•    If the actual building is constructed entirely to this specification it will meet the TER and therefore pass Criterion 1.

•    Table 7.8.11 provides a summary of the concurrent notional building specifications for each category of building.

•    More detailed information can be found in the National Calculation Methodology (NCM) modelling guide.

•    Openings in compartment walls or compartment floors may be made for chimneys, appliance ventilation ducts or ducts encasing one or more flue pipes that meet the provisions in Section 9 of Approved Document B2.

•    If a ventilation appliance is installed in a room containing a natural-draught open-flued combustion appliance or service, such as a gas fire which uses a chimney as its flue, the work will remain notifiable building work.

•    The combustible content of such stairways should be restricted.

•    Where direct escape is impossible, it should be possible to reach a place of relative safety, such as a protected stairway, which is on a route to an exit, within a reasonable distance.

•    Protected stairways provide virtually ‘fire sterile’ areas and should lead to places of safety outside the building.

•    People inside a protected stairway may be considered to be safe from immediate danger from flame and smoke.

•    Flames, smoke and gases must be excluded by using fire-resisting structures or by an appropriate smoke-control system, or by a combination of both these methods.

•    A stairway or shaft that passes directly from one compartment to another should be enclosed in a protected shaft.

    Protected shafts should be restricted to stairs, lifts, escalators, chutes, ducts and pipes.

    Sanitary accommodation and washrooms may be included in protected shafts.

•    If a basement storey contains a habitable room, either an external exit door or window or a protected stairway leading from the basement to a final exit should be provided.

•    A kitchen in student accommodation that is not separated from the stairway by a door should have an interlinked heat detector or heat alarm as well as smoke alarms.

•    Smoke alarms should not be fixed over stairs in student accommodation.

•    The foot of the access stair in a gallery should be no more than 3m from the door to the room containing the gallery.

•    The head of an access stair should be less than 7.5m from any point on a gallery.

•    Any cooking facilities in a room containing a gallery should be remote from the stair to the gallery and positioned such that they do not prejudice the escape from the gallery.

•    There should be direct access from all habitable rooms in a multistorey flat to an internal protected stairway leading to a final exit.

•    A multistorey flat (above 4.5m) without its own external entrance at ground level should have a protected stairway.

•    An alternative exit from a flat should lead to a final exit or common stair.

•    Where an air circulation system circulates air within an individual flat and an internal protected stairway, the following precautions should be taken:

    the protected stairway enclosure should not contain transfer grilles

    ducts passing through the enclosure should be of rigid steel construction

    joints between the ductwork and the enclosure should be fire-stopped

    ventilation ducts to or from the protected stairway should not serve other areas

    mechanical ventilation which recirculates air and serves both the stairway and other areas should be designed to shut down on the detection of smoke within the system.

•    Every flat should have access to alternative escape routes.

•    A single escape route from a flat entrance door is acceptable if:

    the flat is in a storey served by a single common stair (Figure 7.10.1) and every flat is separated from the common stair by a protected lobby or common corridor or has a maximum travel distance for escape in one direction of 7.5m; or

    the flat is situated in a dead-end part of a common corridor served by two (or more) common stairs (Figure 7.10.2 a and b) and the maximum travel distance for escape in one direction is 7.5m.

•    Escape routes in common areas should comply with the following:

    escape in one direction only – there should be no more than 7.5m between a flat entrance door and a common stair

    escape in more than one direction – there should be a maximum 30m from a flat entrance door to a common stair.

•    People should not have to pass through one stairway enclosure to reach another.

•    It is acceptable to pass through a protected lobby of one stairway in order to reach another.

•    In small single-stair buildings, the escape shown in Figure 7.10.3 may be used provided that:

    the top floor of the building is no more than 11m above ground level

    there are no more than three storeys above the ground level storey

    the stair does not connect to a covered car park (unless it is open sided)

    the stair does not serve ancillary accommodation (unless the ancillary accommodation is separated from the stair by a protected lobby, or protected corridor, which has not less than 0.4m² permanent ventilation or is by a mechanical smoke-control system)

    there is a high level openable vent at each floor level with a minimum free area of 1m².

•    There should be some means of ventilating common corridors/lobbies and stairs.

•    In buildings, other than small ones, the corridor adjoining the stair should have a vent.

•    The vent from the corridor/lobby should be as high up as practicable with the top edge at least as high as the top of the door to the stair.

•    There should be a vent, with a free area of at least 1.0m² from the top storey of the stairway to the outside.

•    In single-stair buildings smoke vents on the fire floor and at the head of the stair should be actuated by smoke detectors in the access space to the flats.

•    In buildings with more than one stair, smoke vents may be actuated manually and the control system should ensure that the vent at the head of the stair opens either before, or at the same time, as the vent on the fire floor.

•    On detection of smoke in the common corridor/lobby, the vent(s) on the fire floor, the vent at the top of the smoke shaft and to the stairway should all open simultaneously.

•    Mechanical ventilation may be provided to protect the stair(s) from smoke.

•    Guidance on the design of smoke-control systems is available in BS EN 12101-6.

•    Door(s) should be positioned so that smoke will not affect access to more than one stairway.

•    A separate ventilation system should be provided for each protected stairway.

•    A single common stair may be acceptable in some cases.

•    Access to more than one common stair is preferred.

•    A stair of acceptable width for everyday use is sufficient for escape purpose.

•    Common stairs should have a satisfactory standard of fire protection.

•    A stair may also serve as a firefighting stair.

•    A firefighting stair should be at least 1100mm wide.

•    Every common stair should be within a fire-resisting enclosure.

•    The appropriate level of fire resistance for common stairs is given in Table 7.10.1.

•    If a common stair forms part of the only escape route from a flat, it should not also serve any covered car park, boiler room, fuel storage space or other ancillary accommodation of similar fire risk (except in small buildings).

•    A common stair which does not form part of the only escape route from a flat may also serve ancillary accommodation if it is separated from the ancillary accommodation by a protected lobby or a protected corridor.

•    If the stair serves an enclosed (non-open-sided) car park, or place of special fire hazard, the lobby or corridor should have not less than 0.4m² permanent ventilation or be protected from the ingress of smoke by a mechanical smoke-control system.

•    Every protected stairway should discharge:

    directly to a final exit; or

    via a protected exit passageway to a final exit.

•    Two adjacent protected stairways should be separated by an imperforate enclosure.

•    A protected stairway should be relatively free of potential sources of fire.

•    A protected stairway may be used as a lift well or for an electricity meter.

•    In single-stair buildings, meters located within the stairway should be enclosed within a secure cupboard which is separated from the escape route with fire-resisting construction.

•    If a protected stairway projects beyond, or is recessed from, or is in an internal angle of, the adjoining external wall of the building which has little fire resistance, then the distance between an unprotected area in the external enclosures and unprotected area in the enclosure to the stairway should be at least 1800mm (Figure 7.10.4).

•    Gas service and installation pipes or associated meters may only be installed in a protected stairway if they comply with the Pipelines Safety Regulations 1996, SI 1996 No 825 and the Gas Safety (Installation and Use) Regulations 1998 SI 1998 No 2451.

•    Doors to a protected stairway should be fitted with an automatic release mechanism, otherwise the stairway should not form part of the primary circulation route.

•    Where more than one escape route is available from a storey part of the escape may be via an external escape stair provided that:

    there is at least one internal escape stair from every part of each storey

    the external stair serves a floor not more than 6m above either the ground level or a roof or podium which is itself served by an independent protected stairway

    it is not to be used by members of the public in an Assembly and Recreation building

    it serves only office or residential staff accommodation in an institutional building.

•    If the building has a single access stair, that stair may be external if it serves a floor less than 6m above ground level.

•    All access doors to the stair should be fire-resisting and self-closing.

•    Any part of the external envelope of the building within 1800mm of (and 9m vertically below) the flights and landings of an external escape stair should be of fire-resisting construction.

•    Any part of the building (including any doors) within 1800mm of the escape route from the stair to a place of safety should be protection by fire-resisting construction unless there is a choice of routes from the foot of the stair.

•    Any external stair more than 6m tall should be protected from the effects of adverse weather.

•    In buildings with not more than three storeys above the ground storey, stairs may serve both flats and other occupancies, provided that the stairs are separated from each occupancy by protected lobbies at all levels.

•    In buildings with more than three storeys above the ground storey, stairs may serve both flats and other occupancies provided that:

    the flat is ancillary to the main use of the building and has an independent alternative escape route

    the stair is separated from any other occupancies on the lower storeys by protected lobbies (at those storey levels)

    any automatic fire detection and alarm system in the main part of the building also covers the flat

    any security measures do not prevent escape at all material times.

•    Rooflights in protected stairways may not be constructed of a thermoplastic material.

•    In buildings without sprinklers then every part of every storey that is more than 18m above fire and rescue service vehicle access level should be no more than 45m from a fire main outlet contained in a protected stairway.

•    Additional fire mains may be required in escape stairs.

•    Special measures are needed to prevent a basement fire endangering upper storeys.

•    An escape stair that is the only escape route from an upper storey of a building should not be continued down to serve any basement storey unless it is a small building.

•    The basement should be served by a separate stair.

•    If an upper storey of a building has more than one escape stair, only one of the stairs need be terminated at ground level.

•    Other stairs may connect with the basement storey(s) if there is a protected lobby or a protected corridor between the stair(s) and accommodation at each basement level.

•    In basements and enclosed (non-open-sided) car parks, the lift should be approached by a protected lobby or corridor, unless it is within the enclosure of a protected stairway.

•    Vents should be provided in stairways from basements.

•    Where a flat serves as a workplace for its occupants and for persons who do not live on the premises, the following additional fire precautions will be necessary:

    the maximum travel distance to the flat entrance door or an alternative means of escape (not a window) from any part of the working area should not exceed 18m

    any windowless accommodation should have escape lighting which illuminates the route if the main supply fails. Standards for the installation of a system of escape lighting are given in BS 5266-1.

•    In multistorey buildings, more than one stair may be needed for escape.

•    Every part of each storey will need to have access to more than one stair.

•    Where there is a dead end, an alternative stair should be accessible.

•    The escape from any storey which has more than one escape stair should not pass through one stairway to reach another.

•    It is acceptable to pass through a protected lobby to reach another stair.

•    If a storey or room has two- or more storey exits, it should be assumed that a fire might prevent the occupants from using one of them.

•    The remaining exit(s) need to be wide enough to allow all the occupants to leave quickly.

•    If a ground floor storey shares a final exit with a stair via a ground floor lobby, the width of the final exit should be sufficient to enable a maximum evacuation flow rate equal to or greater than that from the storey exit and stair combined using the following formula:

W = ((N/2.5) + (60S))/80

where:

W = width of final exit in metres

N = number of people served by ground floor storey exit

S = stair width in metres

•    In a multistorey buildings there should be a sufficient number of adequately sized and protected escape stairs.

•    The number of escape stairs needed in a building will be determined by:

    the constraints on the design of horizontal escape routes