Roofs come in all shapes and sizes. Given the nature of roofs, there is a lot to think about when you place a roof onto your building. If it is a flat roof, pitch is definitely a consideration. Drainage to roof drains or scuppers is another consideration as well. But how about pitched roofs? Now we are in an entirely new realm of options, pitches, slopes, and everything else you can throw at a roof design. Also, there are always dormers that no pitched roof can live without! Do the dormers align with the eaves, or are they set back from the building?
This book can’t address every situation you will encounter with a roof system, but it will expose you to the tools needed to tackle these situations yourself. The techniques you will employ in this chapter start with the concept of adding a roof to the model by using the actual floor-plan footprint. As with floors, you will also build the roof’s composition for use in schedules, quantities, and material takeoffs.
The command you’ll probably use most often when working with roofs is the one to place a roof by footprint. Essentially, you will create a roof by using the outline of the building in plan view. There are three roof types you can place by using a footprint:
A flat roof. (Okay, no roof is actually flat, but you get the point.)
A gable roof, which has two sides that are sloped and its ends left open.
A hip roof, which has all sides sloped.
You have only these options while placing a roof by footprint because you are looking at the roof in the plan, which limits your ability to place a roof with nonuniform geometry. Later in the book, you will explore doing just that, but for now let’s start with placing a flat roof by using the footprint of the east wing.
Flat Roofs by Footprint
To begin, open the file you have been following along with. If you did not complete Chapter 6, “Floors,” go to the book’s web page at www.sybex.com/go/revit2012ner. From there you can browse to Chapter 7 and find the file called NER-18.rvt.
The objective of this procedure is to create a flat roof by outlining the building’s geometry in the plan:
1. In the Project Browser, double-click the Roof view in the Floor Plans section (be careful not to click Roof in the Ceiling plans).
2. Zoom in to the east wing.
3. In the view Properties, find the Underlay row and select None from the menu, as shown in Figure 7.1.
4. Click the Apply button.
5. On the Home tab, click Roof Roof By Footprint, as shown in Figure 7.2.
FIGURE 7.2 Clicking Roof By Footprint on the Home tab of the Design bar
6. On the Modify | Create Roof Footprint tab, be sure the Pick Walls button on the Draw panel is selected, as shown at the right of Figure 7.3.
7. On the Options bar, deselect Defines Slope.
8. In the Options bar, make sure the overhang is set to 0´ 0˝(0).
9. Deselect Extend Into Wall Core (if it is selected).
10. Hover your pointer over the leftmost vertical wall. Notice that it becomes highlighted. When you see the wall highlight, press the Tab key on your keyboard. Notice that all the perimeter walls highlight. When they do, pick (left-click) anywhere along the wall. This places a magenta sketch line at the perimeter of the building (see Figure 7.3).
FIGURE 7.3 Adding a sketch line to the perimeter of the building by picking walls
11. On the Modify | Create Roof Footprint tab, click Finish Edit Mode.
13. If you have the elevator shaft masonry walls sticking out of your roof, select all of them, and in the Properties dialog box, change the top constraint to Up To Level: Roof.
FIGURE 7.4 The roof has been added. You still have a lot of work to do, though.
With the roof added, step 1 is out of the way. Now we need to create a roof system. You will do this the same way you created your floor system in Chapter 6.
Creating a Flat Roof System
Although you can use this system for a pitched roof, the steps for a flat roof system differ slightly. In Revit Architecture, there are two ways to look at a roofing system. One way is to create it by using all of the typical roof materials and a large space for the structural framing. In this book, I do not recommend that approach. Creating a roof by using only the roofing components is necessary, but adding the structure will lead to conflicts when the actual structural model is linked with the architectural model. Also, it is hard for the architect to guess what the depth of the structural framing will be. In Revit, you want each component to be as literal and as true to the model as possible. The second way to look at a roofing system, as you are about to explore, is to build the roof in a literal sense—that is, to create the roof as it would sit on the structural framing by others.
The objective of this procedure is to create a roof system by adding layers of materials:
1. Select the roof. (If you are having trouble selecting the roof, remember the Filter tool.)
2. In the Properties dialog box, click Edit Type.
3. Click Duplicate.
4. Call the new roof system 4˝ Insulated Concrete Roof (100mm Insulated Concrete Roof).
5. Click OK.
6. Click the Edit button in the Structure row.
7. Change the material of Structure 1 to Concrete – Cast-in-Place Lightweight Concrete. (You do this by clicking in the cell and then clicking the […] button. You can then select the material from the menu.) After the material is selected, click OK.
8. Change the structure Thickness to 4˝ (100mm), as shown in Figure 7.5.
9. Insert a new layer above the core boundary. (You do this by clicking the number on the left side of the Layers Above Wrap row, and clicking the Insert button below the Layers section, as shown in Figure 7.5.)
FIGURE 7.5 Changing the material and adding a layer
10. Change the function of the new layer to Thermal/Air Layer [3].
11. Click in the Material cell.
12. Click the […] button to open the Materials dialog box.
13. Select Insulation / Thermal Barriers – Rigid Insulation for the material.
14. Click OK.
15. Change Thickness to 4˝ (100mm).
16. Click the Variable button. When you modify the roof, this insulation layer will warp, enabling you to specify roof drain locations.
17. Insert a new layer above Insulation.
18. Give it a Function of Finish 1 [4].
19. Select Roofing – EPDM Membrane.
20. Click OK.
21. Change Thickness to 1/4˝ (6mm), as shown in Figure 7.6.
24. Press Esc or click in open space to clear the roof selection.
Phew! That was a long procedure. It was worth it, though. You will be using this process a lot in Revit Architecture.
For the next procedure, you will add some roof drain locations and then taper the insulation to drain to those locations.
Tapering a Flat Roof and Adding Drains
If you went through the floor procedure in Chapter 6, you will see that the process for tapering a roof is similar to pitching a floor. You may have also noticed that creating a roof system is identical to creating a floor system.
To taper the roof insulation, you must first divide the roof into peaks and valleys, and then specify the drain locations based on the centering of these locations:
1. In the Project Browser, make sure you are in the Roof floor plan.
2. Select the roof. (You may have to use the Filter tool here.)
3. With the roof selected, select the Create Split Lines button shown in Figure 7.7.
4. Draw a line from the points shown in Figure 7.7.
FIGURE 7.7 Start splitting the radial portion of the roof.
5. Press Esc.
6. Select the roof.
7. Click the Add Point button, as shown in Figure 7.8.
8. Add two points at the midpoints marked as 1 and 2 in Figure 7.8.
FIGURE 7.8 Click the Add Point button and add the two points.
9. Click the Add Split Line button and draw a ridge across the entire length of the building, from point 1 to point 2, as shown in Figure 7.9.
10. Press Esc twice or click Modify. Then, on the Home tab, click Ref Plane, as shown at the top right of Figure 7.10.
11. Draw four reference planes spaced approximately the same as in Figure 7.10.
12. On the Annotate tab, click the Aligned Dimension button.
13. Add a dimension string starting at the exterior wall to the left and ending at the exterior wall to the right, as shown in Figure 7.10.
14. Click the blue EQ icon. This equally constrains the reference planes.
15. Press Esc twice or click Modify to terminate the command.
16. Select the roof.
FIGURE 7.9 Drawing a new ridge from the two points shown
FIGURE 7.10 Add a dimension string to the reference planes shown here.
17. Click Add Split Line, as shown in Figure 7.11. Make sure to clear the Chain option.
18. Draw four ridges at the intersections of the reference planes, as shown in Figure 7.11.
FIGURE 7.11 The ridges are in. All that is left is to create some points and start tapering the roof.
19. Press Esc.
20. On the Annotate tab, click the Detail Line button.
21. Draw a diagonal line from the two points shown in Figure 7.12.
22. Click Modify and then select the roof.
23. Click the Add Point button.
FIGURE 7.12 Add a temporary line, and then pick a point to pitch the insulation to.
24. Pick the midpoint of the diagonal line.
25. Notice that there is a node where you picked the point. To access the node, click the Modify Sub Elements button on the Shape Editing panel, as shown in Figure 7.13.
FIGURE 7.13 Click the Modify Sub Elements button to gain access to the points on the roof.
26. Pick the point that you just added. Notice that a blue elevation shows up, as shown in Figure 7.14. Click the elevation, and type -3˝ (-75mm).
FIGURE 7.14 Click here to taper the roof to this point.
27. Press Esc twice.
This process tapers the insulation only in this bay, as shown in Figure 7.15. The objective now is to do the same thing for every bay. Because you cannot copy a point, you need to move the temporary line to the next bay and add a new point.
To further investigate how this roof works, and to see the benefits of this approach rather than drafting the lines in, let’s cut a section through the roof and see how the detail looks:
1. On the Create panel of the View tab, click the Section button.
2. Add a section through the roof, as shown in Figure 7.17.
FIGURE 7.17 Adding a section through the roof at this point
3. In the Type Selector, make sure the type of section is a building section and change View Scale to 3/4˝ = 1´–0˝ (1:20).
4. Change the Detail Level to Fine.
5. Change the View Name option (under Identity Data) to Roof Taper Section (see Figure 7.18).
6. Click the Apply button.
FIGURE 7.18 Changing the properties of the section
7. Double-click on the section head (or you can find the section called Roof Taper Section in the Project Browser).
8. Adjust the crop region so you are looking only at the roof area, as shown in Figure 7.19.
FIGURE 7.19 By adding the points to the roof, you now have an almost perfect section.
This concludes modeling a flat roof. You can now move on to creating a pitched roof. Again, although these types of roofs can be easy to add in the beginning, more work will be required to get them exactly the way you want them.
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Roof By Footprint, as shown in Figure 7.2. 
