Roofs |
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Footprint Roofs |
| As previously stated, 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 11.31). |
Figure 11.31
Simple roof created using the “by footprint" method |
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These roofs are based on a sketched shape that you define in plan view at the soffit level and can be edited in plan and axon 3D views only. The shape can be drawn using the Line tool or can be cre-ated using the Pick Walls method. The best way to conceptualize this method is to understand that the sketched shape defining the main shape of the roof is really just a closed loop of lines, nothing more than that, regardless of whether it’s drawn or picked.
The Pick Walls method provides an intelligent selection method, so if you pick walls as refer-ences to generate the sketch lines, the lines will maintain a smart relationship with the walls. The Pick Walls method is the suggested approach for creating roofs by footprint. By picking the walls to generate the sketch for the roof, you are creating an exclusive relationship between the walls and the roof so that if the design of your building later changes (wall position, level height, etc.), the roof will follow that change and adjust to the new wall position (Figure 11.32). Like any change in Revit, this happens everywhere in all views (plan, section, 3D). |
Figure 11.32
Using the Pick method:
(A) original roof;
(B) entrance wall posi-tion changed, roof updates automatically;
(C) the angle of the wall right from the entrance changed, the roof changes to a new shape. |
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| To guide you through the creation of roof by footprint and explain some of the main principles and tools, here is a brief exercise demonstrating the steps: |
- Open a plan view and create a building footprint similar to Figure 11.33.
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Figure 11.33
Draw a simple set of walls. |
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- From the Design bar, click the Roof tool and choose Roof By Footprint.
- Select the Pick Walls tools.
- To define whether you want a sloped or flat roof, you will use the Defines Slope check box in the Options bar. The Overhang parameter allows you to define the value of the roof over-hang beyond the wall. When the “Extend into wall (to core)" option is checked, the overhang
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| is measured from the wall core. If the option is unchecked, the overhang is measured from the exterior face of the wall. When you’ve chosen to create a roof by footprint, the Options bar makes these tools available. |
- After defining these settings, place your cursor over one of the walls (don’t click), and using the Tab key, pick all connected walls. Your display should look like Figure 11.34.
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Figure 11.34
Roof sketch lines are automatically drawn after Tab-selecting the bounding walls and entering the com-mand, and they are offset from the walls by the value of Offset as defined in the Options bar. |
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- Click the Finish Roof button.
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If the shape of the roof doesn’t respond to your expectations, at any time you can select the roof and select Edit from the Options bar to change the shape of the roof sketch lines or their slope. To change the slope definition or angle of individual portions of the roof, select the sketch line and toggle the Defines Slope button in the Options bar, or click on the slope value that is displayed when you select the sketch line.
Here are some of the important instance properties you should be aware of and need to set prop-erly; all are found in the dialog shown in Figure 11.35. |
Base Level As in other Revit elements, this is the level at which the roof will be placed.
The roof will move with this level if it changes height.
Room Bounding When this is checked, the roof geometry will have an effect on calculating room
area and volume.
Related to Mass This property will be active only if a roof has been created with the By
Face method (Massing tools).
Base Offset From Level This option will lower or elevate the base of the roof relative to the base level.
Cutoff Level Many roof shapes require a combination of several roofs on top of each other—for this you would need to cut off the top of a lower roof to accommodate space and the creation of the next roof in the sequence. Figure 11.36 shows an excellent example of this technique.
Cutoff Offset When the Cutoff tool is applied, the Cutoff Offset value also becomes active and allows for setting cutoff distance from the level indicated in the Cutoff Level parameter |
Figure 11.35
Roof Properties dialog |
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Figure 11.36
Cutoff level applied to the main roof, and a secondary roof built on top of the main roof using the cutoff level as a base |
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Rafter Cut This defines the eave shape. You can select from Plumb Cut,
Two Plumb Cut, Two Plumb Square. When Two Plumb Square is selected as a choice, the Fascia Depth parameter is activated and you can set the value for the depth.
Rafter or Truss With Rafter, the offset of the base is measured from the inside of the wall.
If you choose Truss, the plate offset from the base is measured from the outside of the wall. Figure 11.37 is a typical example of a roof by rafter cut. |
Figure 11.37
Construction drawing of rafter detail |
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