The traditional floor object is a sketch-based element comprised of any number of material layers as defined by the user. The top of the floor object is its reference with respect to the level on which it was created. As such, changes to a floor's structure will affect its depth down and away from the level. You can start modeling floors with generic types, which are similar to generic walls containing a single layer, and then change the generic floors to more specific assemblies later in the development of your project. To do this, simply select one or more floors and choose a different wall type from the Type Selector in the Properties Palette. You can also use the Match Type Properties tool located in the Clipboard panel of the Modify tab of the ribbon.

You can use floors in a variety of ways to meet the needs of a specific phase of design. In early phases, for example, you can create a floor type to represent the combined floor, structure, plenum, and ceiling assemblies of a building. Commonly referred to as the sandwich, a sample is shown in Figure 14.1.

Figure 14.1. A single floor type may be used to show the entire floor/ceiling sandwich in early design.

During intermediate phases of design, you can model ceilings so the floor types can include only the floor and a structural layer, as shown in Figure 14.2. Columns may be created, but more precise horizontal structural framing may not be modeled yet. The layer within the floor type represents an assumption of the maximum depth of structural framing.

Figure 14.2. This floor assembly includes an assumption for the depth of structural framing.

In later phases approaching and including construction, floors should be modeled as close to actual conditions as possible. You should accommodate detailed finish conditions for floors as well as coordination with a resolved structural system. Accurate modeling of these conditions will help support consistent quantity takeoffs and interference detection. Figure 14.3 illustrates an example of a more accurate floor slab.

Figure 14.3. Floor assemblies for construction should be accurate and separate from structural framing.

These floor assembly types are offered as suggestions for the sake of increased productivity. As such, they should be used with care, especially when performing quantity takeoffs for estimating. For example, the area of floor will be the only accurate value to be extracted from a floor sandwich model in early design, not a volumetric material takeoff. For more information on the use of models by others, we recommend referring to the AIA document E202 BIM Protocol Exhibit, which lists authorized uses of a model at various levels of development. You can download a sample of this document for free from www.aiacontractdocuments.org/bim.

Collaboration and the Ownership of Floors

Whether or not you are working under an integrated project delivery (IPD) contract, the so-called ownership of floors should be carefully considered for the collaboration process between an architect and a structural engineer. Floors can be one of the most contentious elements of a building design because they can be simultaneously construed as architecture and structure.

The model element author (MEA) for floors should be discussed and clearly defined for each phase in your project BIM execution plan. Remember that element ownership can pass between the architect and the structural engineer when it is appropriate for a given phase. For example, the architect may choose to be the MEA for floors in schematic design, but pass ownership to the structural engineer in design development and construction documentation.

The structural floor is new to Revit Architecture 2011and is similar to a traditional floor but has structural functionality such as the ability to indicate span direction and to contain structural profiles. For example, you can specify a composite metal deck profile, which will display in sections and details generated within your project.

If you are working with a project file that has been upgraded from a previous version of Revit, the only way to create a new structural floor is to create a new one by going to the Home tab, locating the Build panel, and choosing Floor

Figure 14.4. Structural parameter in a floor's instance properties

Once the Structural parameter check box has been selected for a floor, you can edit its type properties to add a structural decking layer. Let's create a new structural floor so you can explore how this is done:

Figure 14.7. Structural floor as represented in Coarse detail level (left) and Medium detail level (right)

This floor modeling method is used when you have generated an in-place mass or loaded a mass family. After you assign mass floors to a mass, you can use the floor by face method to assign and manage updates to floors, as shown in Figure 14.8. This type of floor modeling is discussed in greater detail in Chapter 9.

Figure 14.8. The Floor By Face tool can be used to manage slabs in more complex building designs.

A pad is technically not a floor but has similar properties to a floor. What differentiates a pad is its ability to cut into a toposurface and define the lowest limits of a building's basement or cellar. If desired, the pad can be configured to represent a slab on grade, as shown in Figure 14.9.

Figure 14.9. A pad can be configured as a slab on grade for a basement.

Slab Edge is a tool that allows you to create thickened portions of slabs typically located at the boundaries of floors. A slab edge type is composed of a profile family and a material assignment. It is important that the material assignment of the slab edge match that of the floor to which you will apply the slab edge in order to ensure proper joining of geometry. Let's explore the application of a slab edge to a floor at grade:

Figure 14.10. Thickened slab edge applied to the bottom of a floor

You can apply a great deal of flexibility to a floor assembly in early design. As we described earlier, you can create a floor for early design phases that accommodates the floor, structure, plenum, and ceiling in a single floor type. You can also apply a customized edge to this type of assembly for more creative soffit conditions at exterior walls, as shown in Figure 14.11.

Figure 14.11. Customized edge applied to a floor assembly in early design

Let's run through a short exercise so you can practice this skill:

Figure 14.15. The edge of the floor sandwich assembly for Level 1 has been customized.

Because floors, ceilings, and roofs are sketch-based objects, the method you use when creating the boundary lines is critical to the behavior of the element to those around it. The recommended method is to use the Pick Walls option, as shown previously in Figure 14.15.

By selecting the walls to generate the sketch for the roof, you are creating an intelligent relationship between the walls and the roof. If the design of your building later changes and the wall position is modified, the roof will follow that change and adjust to the new wall position without any intervention from you (Figure 14.16).

Figure 14.16. Using the Pick method: (A) original roof; (B) the entrance wall position has changed, and the roof updates automatically; (C) the angle of the wall to the right of the entrance has changed, and the roof changes to a new shape.

Also notice in Figure 14.16 that the illustrated roof was generated with overhangs beyond the exterior faces of the walls. You can specify an overhang or offset value for a floor, ceiling, or roof in the Options Bar before picking walls to define the sketch.

If your building design is using curtain walls, be careful with the location lines of these walls. The location line of a curtain wall is defined relative to the offsets specified in the mullion and panel families that comprise the curtain wall type. As discussed in Chapter 13, you have many options when defining the relative location line of your curtain wall types. Refer to the exercise in the "Structural Floor" section earlier in this chapter for an example of picking curtain walls with an offset based on a centered location line.

One of the easiest ways to divide a floor surface for thin finishes is using the Split Face and Paint tools. This method will require a floor to be modeled and an appropriate material defined with at least a surface pattern. Note that you can only schedule finishes applied with the Paint tool through Material Takeoff schedules. Let's explore this method with a quick exercise.

Figure 14.18. Completed application of carpet tile material to a split face on a floor

Thicker finish materials such as tile, stone pavers, or terrazzo can be applied as unique floor types and modeled where required. For large areas of finish such as a public atrium or airport terminal, you can simply assign these materials within the layers of a floor assembly. When you need to add smaller areas of thick floor finishes, there are two scenarios you may encounter: with a depressed floor and without.

In areas such as bathrooms, a thick-set tile floor may require the structural slab to be depressed in order to accommodate the thickness of the finish material. In the example illustrated in Figure 14.19, the main floor object has been cut with an opening at the inside face of the walls. Another floor has been modeled with a negative offset value to accommodate the thickness of the tile material, and the tile has been placed as a unique floor element.

If you don't need a finish but just a slab depression, you can create it with an in-place void extrusion. Simply click the Home tab on the ribbon and click Component

Figure 14.19. The thick tile finish and depressed slab are modeled as separate elements.

Finally, if the structural requirements allow a thick finish to be applied to a floor without dropping the structural slab, a finish floor element can be modeled directly in place within the structural slab. As shown in Figure 14.20, the tile floor has been graphically embedded in the structural floor using the Join Geometry tool. To do this, click the Modify tab on the ribbon and click Join Geometry. Make sure to pick the finish floor before the structural floor or you will get an error.

Figure 14.20. The thick tile finish floor has been joined with the structural floor.

Use the roof by footprint method to create any standard roof that more or less follows the shape of the footprint of the building and is a simple combination of roof pitches (Figure 14.21).

Figure 14.21. A simple roof created using the roof by footprint method

These roofs are based on a sketched shape that you define in plan view at the soffit level and that can be edited at any time during the development of a project from plan and axon 3D views. The shape can be drawn as a simple loop of lines, using the Line tool, or can be created using the Pick Walls method that also should result in a closed loop of lines.

To guide you through the creation of a roof by footprint and explain some of the main principles and tools, here is a brief exercise demonstrating the steps:

If the shape of the roof doesn't correspond to your expectations, you can select the roof and select Edit Footprint from the Mode panel in the Modify | Roofs tab to return to Sketch mode, where you can edit lines, sketch new lines, pick new walls, or the modify the slope.

To change the slope definition or angle of individual portions of the roof while editing a roof's footprint, select the sketch line of the roof portion for which you wish to change the slope and toggle (check) the Defines Slope button in the Options Bar, toggle the Defines Slope parameter in the Properties dialog box, or right-click and choose Toggle Slope Defining. If you mistakenly made all roof sides with slope but wanted to make a flat roof, you can Tab-select all sketch lines that form the roof shape and clear the Defines Slope box in the Options Bar.

Roof slope can be measured in different ways: it can be set as an angle or percentage rise. All slope measuring options can be found in the Manage tab by selecting Project Units in the Project Settings panel and then selecting Slope to open the Format dialog box (see Figure 14.25). If the current slope value is not in units you wish to have (suppose it displays percentage but you want it to display an angle), change the slope units in the Format dialog box—you will not be able to do that while editing the roof slope. Setting it here means specifying the way you measure slopes for the entire project.

Figure 14.25. Format dialog box for slopes

Here are some of the important Instance Properties you should be aware of and need to set properly; all are found in the Properties dialog box shown in Figure 14.26.

Figure 14.26. Roof instance properties

Figure 14.28. Rafter setting (left) and truss setting (right) for roofs

The roof by extrusion method is best applied for roof shapes that are generated by extrusion of a profile, such as sawtooth roofs, barrel vaults, and waveform roofs. Like the roof by footprint method, it is based on a sketch; however, the sketch that defines the shape of the roof is drawn in elevation or section view (not in plan view) and is then extruded along the plan of the building (see Figure 14.29).

Figure 14.29. An extruded spline-shaped roof

To briefly explain the concept: you create a roof by extrusion by defining a profile in elevation or 3D that is then extruded above the building. The extrusion is usually based on a work plane that is not perpendicular to the building footprint, as illustrated in Figure 14.30. If the shape of the building is nonrectangular in footprint or the shape of the roof you want to create is not to be rectangular, this tool will let you carve geometry from the roof to match the footprint of the building or get any plan shape you need using a plan sketch.

Figure 14.30. Extruded roof created at an angle to the building geometry

With sketch-based design, any closed loop of lines creates a positive shape, every loop inside it is negative, the next one inside that negative one will be positive, and so on. In Figure 14.31, a roof by extrusion was drawn at an angle to the underlying walls, but the final roof shape should be limited to a small offset from the walls. To clip the roof to the shape of the building footprint, the Vertical Opening tool was used to draw, in plan view of the roof, a negative shape that will remove the portions of the roof that extend beyond the walls.

Figure 14.31. The Vertical Opening tool with two sketch loops trims the roof to the inner loop.

The roof in-place technique accommodates roof shapes that cannot be achieved with either of the previously mentioned methods. It is the usual way to model historic roof shapes or challenging roof geometries such as those illustrated in Figure 14.32. The figure shows a barrel roof with half dome (Extrusion + 1/2 Revolve), a dome roof (Revolve only or Revolve + Extrusion), and a traditional Russian onion dome (Revolve only).

Figure 14.32. Examples of modeled in-place roofs

To create an in-place roof, select the Home tab in the ribbon and click Component

Figure 14.33. Organic-shaped roof created using the Swept Blend modeling technique

The Roof By Face tool is to be used when you have created an in-place mass or loaded a mass family. These types of roofs are typically more integrated with the overall building geometry than the examples we've shown for in-place roofs. You can find more detailed information about using the roof by face method in Chapter 9, "Advanced Modeling and Massing."

In Chapter 13, "Walls and Curtain Walls," you learned that a curtain wall is just another wall type made out of panels and mullions organized in a grid system. Similarly, sloped glazing is just another type of a roof that has glass as material and mullions for divisions. Using sloped glazing, you can make roof lights and shed lights and use them to design simple framing structures.

To create sloped glazing, make a simple pitched roof, select it, and use the Properties dialog box to change the type to Sloped Glazing. Once you have done that, activate a 3D view and use the Curtain Grid tool from the Build panel of the Home tab on the ribbon to start applying horizontal or vertical grids that define the panel sizes; then you can apply mullions using the Mullion tool in the Build panel. Figure 14.34 illustrates an example of a standard gable roof that has been converted to sloped glazing.

Figure 14.34. Sloped glazing is created by switching a standard roof to the Sloped Glazing type and assigning grids and mullions.

If your design calls for a sloped roof with an unusual footprint that does not easily lend itself to utilizing the Defines Slope property of boundary lines, slope arrows can be added within the sketch of the roof. First create the sketch lines to define the shape of a roof, but don't check Defines Slop in the Options Bar. Instead, choose the Slope Arrow tool from the Draw panel. Draw the slope arrow in the direction you want your roof to pitch. Select the arrow and in the Properties dialog box, you can set any of the parameters as shown in Figure 14.35. The Specify parameter can be set to either Height At Tail or Slope. If you choose Height At Tail, be sure to specify the Height Offset At Head parameter as the end result of the desired slope.

Figure 14.35. Defining the properties of a Slope Arrow added to an irregular footprint roof sketch

Creating a Dormer Step-by-Step

Roofs with dormers generally cause grief for architects, so we'll guide you through the creation of one:

1. Create the base of a building, set up three levels, and create a Roof By Footprint with Defines Slope checked for all sides.

2. Approximately in the position indicated below, on Level 2, create the four walls of a dormer. Set their height to a value that makes them extend above the roof. (For easier verification, create a cross-section through the dormer to check the height of the dormer walls and, if necessary, modify their height in the Element Properties so that they extend above the roof.)

   

3. Using the Roof By Footprint tool, create a pitched roof on top of the dormer walls.

4. If you switch to a side elevation view, you will notice that the dormer roof probably does not extend to meet the main roof, so you will need to use the Join/Unjoin Roof tool, located in the Modify tab in the Edit Geometry panel, to join the main roof and the dormer. Select the Join/Unjoin Roof tool, select the main roof as the target, and then select the edge of the dormer roof to extend.

   

5. From the Opening panel on the Home tab, select Dormer. Now pick first the main roof, then the dormer roof, and then select the sides of the walls that define the dormer. Select the inside faces of the walls. Unlike most sketches, in this case you will not need to provide a closed loop of lines. Finish the dormer opening.

   

6. The last thing to do is to go back to the section view you previously created and edit the elevation profile of the side walls to make sure they don't extend below or above the roofs. Note that you should not use the Top/Base Attach tool; instead, select the wall and use the Edit Profile tool available in the Mode panel of the Modify | Walls tab to edit its elevation profile and manually resketch the edge lines of the walls to get the triangular elevation profile as shown.

Your dormer opening is now correct. You will see that it has cut the roof in two directions, as a true dormer needs to.

As a final option, you can convert the front wall of the dormer to a storefront wall type or add a window.

Let's do an exercise that shows you how to make a roof with a sloped topping like the one shown in Figure 14.37 (shown in plan view).

Figure 14.37. A roof plan showing a roof divided in segments, with drainage points

Follow these steps:

What if you wanted the insulation to be tapered but not the structure? For that, the layers of the roofs can now have variable thickness. Let's see how to apply a variable thickness to a layer of the roof assembly.

Note that you will only be able to modify an adjustable layer of a floor or roof with a negative value to the next nonadjustable layer of the assembly. In the earlier exercise, for example, if you modified the drainage points by more than −0'-5" (−13cm), an error would be generated, and the edits to the roof would be removed. You must think about the design requirements of your roof or floor assembly when planning how to model adjustable layers. An alternative approach to the previous exercise might have been to increase the thickness of the insulation layer in the roof assembly to that required at the high pitch points. The drainage points could then be lowered relative to the boundary edges and ridge lines.