Modeling a Floor

The traditional floor object is a sketch-based element that comprises 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 contain a single layer, and then change the generic floors to more specific assemblies later in the development of your project. 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 13.1.

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 13.2. 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.

In later phases of documentation 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 13.3 illustrates an example of a more accurate floor slab.

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 a 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 other disciplines, we recommend referring to the AIA document G202-2013 Project BIM Protocol Form, which lists authorized uses of a model at various levels of development. You can learn more about AIA contract documents at www.aia.org.

With a basic understanding of floors as elements of the building, let’s look at some properties of floors that allow expanded uses in the project model. These properties and floor types can help expand your use of floor systems to create better documentation.

Creating a Structural Floor

The structural floor 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. You can create a structural floor by selecting the floor element and clicking the instance property called Structural (Figure 13.4, fifth item from the top). Because Structural is an instance property, any floor type can become a structural floor.

After you select the Structural parameter check box 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:

1. Open the file c13-Floors-Start.rvt or c13-Floors-Start-Metric.rvt from the book’s web page (www.sybex.com/go/masteringrevitarch2016), and activate the Level 3 floor plan.
2. Go to the Architecture tab in the ribbon, and from the Build panel, select Floor ➢ Floor: Structural.
3. In the Draw panel of the contextual tab in the ribbon, make sure your options are set to Boundary Line with the Pick Walls tool, as shown in Figure 13.5.

4. In the Options bar, specify an offset of 0′-3″ (75 mm).

   This setting will place the floor boundary just within the inner face of the curtain wall mullions because the location line of the curtain wall is at the center of the mullions that are 5″ (125 mm) deep.

5. Begin picking the exterior curtain walls by selecting one of the north-south–oriented walls first.

   The first wall that you pick will determine the span direction of the structural floor. You can change this at any time by picking the Span Direction tool from the Draw panel and then selecting one of the boundary lines in the floor sketch.

6. Pick the remaining exterior walls to complete the floor boundary.

       After you finish defining the boundary lines of the floor, you will create a new floor type. If the Properties palette isn’t open, press Ctrl+1 on the keyboard, type PP, or click the Properties icon in the ribbon.

7. Click Edit Type in the Properties palette. Select Generic - 12″ or Generic - 300 mm as the active type and click Duplicate. Name the new type Structural Slab.
8. In the Edit Type dialog box, click the Edit button in the Structure row to open the Edit Assembly dialog box.
9. In the Edit Assembly dialog box, find the layer of the assembly that represents the generic floor you duplicated. This should be row 2. Change the material of this layer to Concrete – Cast-In-Place Concrete and change the thickness to 0′-6″ (150 mm).

10. Select row 3 and click the Insert button. There should now be four layers. Select the new row 3 and set its function to Structural Deck [1].

    The new Structural Deck properties appear below the layers, as shown in Figure 13.6.

11. The value for Deck Profile should default to Form Deck_Non-Composite: 2′ × 6″ or M_Form Deck_Non-Composite: 50 × 150 mm, but this depends on whether you have a structural deck profile loaded into your project.

    If you don’t have a structural deck profile loaded, finish the floor, select the Insert tab of the ribbon, and click Load Family. In your default Autodesk content library, find the Profiles folder and open the Metal Deck subfolder. Pick an appropriate deck profile and click Open to load it. Select the Structural Slab floor and click Edit Type in the Properties palette to continue the exercise.

12. Activate Wall Section 1 and you should see the completed slab at Level 3.

    Notice that you do not see the details of the structural decking when Detail Level is set to Coarse.

    If you activate the callout at Level 3 (Detail At Level 3), you will see the structural decking because the callout’s detail level is set to Medium. This difference is illustrated in Figure 13.7.

Modeling Floor by Face

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 13.8. This type of face-based modeling is discussed in greater detail in Chapter 8, “Advanced Modeling and Massing.”

Defining a Pad

A pad is technically not a floor but has properties similar to a floor. What differentiates a pad is its ability to cut into a toposurface or ground plane and define the lowest limits of a building’s basement or cellar. If desired, you can configure the pad to represent a slab on grade, as shown in Figure 13.9. The Pad tool can be found on the Model Site panel of the Massing & Site tab. If you don’t see this tab, you can access it by clicking the Application button and choosing Options ➢ User Interface.

For a more detailed exercise on creating building pads, refer to Chapter 3, “The Basics of the Toolbox.”

Creating a Custom Floor Edge

You can apply a great deal of flexibility to a floor assembly in early design. As we described previously, 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 13.12.

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

1. Open the file c13-Design-Floor.rvt from the book’s web page or continue with the file from the previous exercise and activate the view Section 1.
2. Select the floor at Level 1 and open the Properties palette. Change the type to Design Floor Sandwich.
3. Begin a new in-place component by going to the Architecture tab and selecting Component ➢ Model In-Place from the Build panel.

4. Set the Family Category to Floors and specify the name as Floor Edge-L1.

   You are now in Family Editing mode and the ribbon will have different tabs and panels.

5. Click the Create tab and select Void Forms ➢ Void Sweep from the Forms panel.

6. Click the Pick Path tool from the Sweep panel and choose all four top edges at the perimeter of the floor at Level 1.

      

   You can activate the 3D view Floors Only to complete the picking of all four edges, as shown in Figure 13.13.

7. Click the Finish Edit Mode icon in the Mode panel when all four edges of the floor have been picked.

8. Open the Properties palette if it isn’t already visible.

   You might need to reactivate the Select Profile mode if the Properties palette lists only Family: Floors. To do this, click Select Profile in the contextual tab of the ribbon.

9. In the Profile parameter, select SD Sandwich Edge : Type 1 from the drop-down list, as shown in Figure 13.14.

   The SD Sandwich Edge profile has been preloaded for the convenience of this exercise. If you would like to explore how this profile was created, expand the Families tree in the Project Browser and find Profiles ➢ SD Sandwich Edge. Right-click it and choose Edit from the context menu.

10. You may need to adjust the orientation of the profile so that it faces in toward the floor, as shown in Figure 13.15. To do so, make sure the profile is selected, and click the Flip button in the Options bar or check the Profile Is Flipped option in the Properties palette.
11. Switch to the Modify | Sweep tab in the ribbon and click the Finish Edit Mode icon from the Mode panel.
12. Switch to the Modify | Void Sweep tab in the ribbon and select Cut ➢ Cut Geometry in the Geometry panel. Pick the void sweep and then the floor at Level 1.

13. Click Finish Model in the In-Place Editor panel at the right end of the ribbon.

    Activate the Section 1 view, and you should see that the floor sandwich assembly at Level 1 has been customized in a similar way to the floor at Level 2 (Figure 13.16). You can experiment with adding embellishing detail components as shown in the section.

Using a Split Face for Thin Finishes

One of the easiest ways to divide a floor surface for thin finishes is to use 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. You can schedule finishes applied with the Paint tool only through Material Takeoff schedules. Let’s explore this method with a quick exercise:

1. Open the file c13-Design-Floor.rvt from the book’s web page or continue with the file from the previous exercise and activate the Level 1 floor plan.

   You will see an area of the floor that is bounded by a wall and two reference planes.

2. Click the Modify tab in the ribbon, activate the Split Face tool from the upper-right corner of the Geometry panel, and pick the floor in the Level 1 floor plan.

3. Draw a rectangle in front of the three interior walls, as shown in Figure 13.17.

   You can constrain—or lock—the sketch lines to the interior walls, reference planes, and floor edge. You may do so in this exercise, but use constraints sparingly in larger projects to avoid slower model performance and updating calculation time.

   Also notice that you generated a complete rectangular sketch instead of only three bounding lines. You do not need to draw the boundary line at the edge of the floor; however, if you don’t include that line and the floor shape is modified in the future, the split face may be deleted because it is no longer a closed-loop sketch.

4. Click the Finish Edit Mode icon in the Mode panel.
5. Return to the Modify tab in the ribbon and activate the Paint tool in the Geometry panel, just below the Split Face tool.

6. In the Material Browser, type carpet in the filter search at the top.

   This will minimize your choices, allowing you to select Carpet Tile from the filtered list (Figure 13.18).

7. In the Level 1 floor plan, click near the edge of the split face you created earlier to assign the material.

   The result should look like Figure 13.19.

8. Click the Done button in the Material Browser to exit the Paint command.

Modeling Thick Finishes

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 assign these materials within the layers of a floor assembly. When you need to add smaller areas of thick floor finishes, you may encounter one of two scenarios: 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 Figure 13.20, 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. Select the Architecture tab in the ribbon and click Component ➢ Model In-Place. Choose the Floors category and create a void extrusion where you need a slab depression. Remember to use the Cut Geometry tool to cut the void from the floor before finishing the family. As an alternative, you can create a floor-based generic family that contains a parametric void extrusion. You can download the file c13-Slab-Depression.rfa as an example of this type of family from the book’s web page.

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 13.21, the tile floor has been graphically embedded in the structural floor using the Join Geometry tool. To do this, click the Modify tab in the ribbon and click Join Geometry. Be sure to pick the finish floor before the structural floor or you will get an error.

Constructing a Roof by Footprint

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 13.25).

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, which 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:

1. In a new project using any default template, open a Level 1 plan view and create a building footprint similar to Figure 13.26.

   Make sure the height of the walls is set to Unconnected: 20′-0″ (6000 mm).

2. Activate the Level 2 plan; then select the Architecture tab in the ribbon and click Roof ➢ Roof By Footprint.
3. From the Draw panel in the Modify | Create Roof Footprint tab, select the Pick Walls tool (this should be the default).

4. When you’ve chosen to create a roof by footprint, the Options bar displays the following settings (change the Overhang value to 1′-0″ (300 mm)).

   

   To define whether you want a sloped or flat roof, use the Defines Slope check box in the Options bar. The Overhang parameter allows you to define the value of the roof overhang beyond the wall. When the Extend To Wall Core option is checked, the overhang is measured from the wall core. If the option is deselected, the overhang is measured from the exterior face of the wall.

5. After defining these settings, place the cursor over one of the walls (don’t click), and using the Tab key, select all connected walls.

   Your display should look like Figure 13.27.

6. Select the three walls within the alcove, open the Properties palette, and uncheck the Defines Roof Slope parameter, as shown in Figure 13.28.
7. Click the Finish Edit Mode icon in the Mode panel of the ribbon. If you are prompted with the question, “Would you like to attach the highlighted walls to the roof?” click the Yes button. Activate a 3D view, and your roof should like the image in Figure 13.25 shown previously.

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 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 want to change the slope and toggle (check) the Defines Slope button in the Options bar, toggle the Defines Roof Slope parameter in the Properties palette, 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. You can dynamically change the roof slope by selecting the roof and then selecting the blue grips (Figure 13.29) and dragging them either up or down to make the roof pitch steeper or shallower. This is a great way to make quick (although not precise) edits to the roof pitch.

Roof slope can be measured in two different ways: as an angle or as a percentage rise. You can find all slope-measuring options 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 13.30). If the current slope value is not in units you want 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.

Applying a Roof by Extrusion

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 13.31).

Roofs by extrusion do not have an option to follow the building footprint, but that is often needed to accommodate the requirements of the design. To accomplish this, you can use the Vertical Opening tool to trim the edges of an extruded roof relative to the building outline.

Let’s briefly review the concept behind the Vertical Opening tool: 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 shown in Figure 13.32. 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.

    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 13.33, 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.

Roof In-place

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 13.34. The figure shows a barrel roof with a half dome (Extrusion + 1/2 Revolve), a dome roof (Revolve only or Revolve + Extrusion), and a traditional Russian onion dome (Revolve only).

To create an in-place roof, select the Architecture tab in the ribbon and click Component ➢ Model In-Place from the Build panel. Select Roofs from the Family Category list and click OK. While you remain in the In-Place Family editing mode, you can create any roof shape using solids and voids of extrusions, blends, revolves, sweeps, and swept blends (Figure 13.35). More advanced editing techniques are discussed later in this chapter, in the section “Using Advanced Shape Editing with Floors and Roofs.”

Creating a Roof by Face

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 face-based methods in Chapter 8.

Creating a Sloped Glazing

In Chapter 12, 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 palette 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 Architecture tab in 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 13.36 illustrates an example of a standard gable roof that has been converted to sloped glazing. Refer to Chapter 12 for more information on using the Curtain Grid and Mullion tools.

Using Slope Arrows

If your design calls for a sloped roof with an unusual footprint that does not easily lend itself to using 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 Slope 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 palette, you can set any of the parameters, as shown in Figure 13.37. 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.

Using Additional Roof Tools

The following three roof tools (Figure 13.38) can be found under the Roof flyout:

• Roof : Soffit
• Roof : Fascia
• Roof : Gutter

Each of these tools behaves in a similar fashion—it uses a profile that is swept along the edge of the roof.

The difference between these tools is fairly simple. The Soffit tool will sweep a profile to the underside of a roof overhang parallel to the ground. The Fascia tool will sweep a profile along the vertical face of the roof edge, and the Gutter tool will sweep a profile along one of the edges of the roof. Try these tools on the roofs you’ve created in this chapter to better understand how they react to roof conditions. You can see how the Gutter tool looks using the default profile in Figure 13.39.

Don’t feel you’re limited to residential uses with these tools—as an example, the Gutter tool can be used to create a break metal cap for a flat roof parapet. Do be careful when you are picking an edge to apply the Gutter tool. The best approach is to pick in-plan views because the Gutter tool will default to the lower of the two edges so your gutters will be all placed at a consistent level.

Creating a Roof with a Sloped Topping

Let’s work through an exercise that shows you how to make a roof with a sloped topping like the one shown in Figure 13.41 (shown in plan view).

Follow these steps:

1. Open c13-Roof-Edit.rvt or c13-Roof-Edit-Metric.rvt from the book’s web page. Activate the Roof floor plan.
2. Select the roof that has already been prepared for you.
3. Activate the Add Split Line tool (the color of the rest of the model grays out while the roof lines are dashed green).

4. Sketch two ridge lines to divide the roof into three areas that will be independently drained.

   The ridge lines will be drawn in blue.

5. Using the same tool, draw diagonal lines within those areas to create the valleys.

   Make sure you zoom in closely when drawing the diagonal lines, and be sure that you are snapping in the exact same dividing points. (If you notice that the split lines are not snapped to the correct points, select the Modify Sub Elements tool, pick the incorrect lines, delete them, and try again.)

   You have split the roof surface into many regions, but they are still all at the same height and pitch. You should have a roof that looks like Figure 13.42.

   Press the Esc key or click the Modify button to stop the editing mode.

6. Switch to a 3D view.
7. To add a slope, you need to edit the height of the drainage points or the heights of the edges and ridges created by the split lines. For this exercise, you will raise the elevation of the boundary edges and ridges. Activate the Modify Sub Elements tool and select an edge of the roof (dashed green line). New controls that allow you to edit the text will appear, and you can either move the arrows up and down or type in a value for the height. Type in 1′-0″ (300 mm).
8. Repeat step 7 for all boundary edges and the two north-south split lines forming the ridges between the drainage areas.
9. Make a section through the roof—if possible, somewhere through one of the drainage points. Open the section; change Detail Level to Fine to see all layers.

The entire roof structure is now sloped toward the drainage point.

Applying a Variable Thickness to a Roof Layer

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.

1. Continuing with the c13-Roof-Edit.rvt or c13-Roof-Edit-Metric.rvt file from the previous exercise, select the roof, and in the Properties palette select Edit Type to view the roof’s type properties. Click Edit in the Structure row to edit the layers of the roof assembly.
2. Activate the preview. You will notice that in the roof-structure preview, you do not see any slopes. That is correct and will not change. This preview is just a schematic preview of the structure and does not show the exact sloping. Look for the Variable column under Layers, as shown in Figure 13.43. This allows layers of the roof to vary in thickness when slopes are present. Check the Variable option for the insulation material.

3. Go back to the section view and observe the changes in the roof assembly.

   As you can see, only the insulation is tapered, while the structure remains flat.

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 previous exercise, for example, if you modified the drainage points by more than –0′-5″ (–130 mm), 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.