Join Paul F. Aubin for an in-depth discussion in this video Attaching walls to roofs, part of Revit 2018: Essential Training for Architecture (Imperial).
- [Voiceover] For many of the traditional forms of roofs like hips, gables, shed roofs, a footprint roof will achieve the job quite nicely such as this example right here, but in cases where you want to do a barrel vault or some certain kinds of canopies and so on, you might choose to use a different form of roof, an extrusion roof. So in this example here, on the backside of this building here I want to add a canopy and I'm gonna use the extrusion roof for that. Now I can hold my Shift key down and drag the wheel to spin this around. I can also use the view cube to help me do that so what I'm going to do is click the top corner of this view cube right here and that will spin the model around in orient and it's this surface right here that I want to work on.
Now I could work directly in 3D but sometimes it's a little easier to make the sketch if you're looking right at that plane so instead I'm actually going to open up the west elevation and I want to draw the shape of this extrusion roof directly on the surface of this wall. Now when we go to the architecture tab, the default button for the roof is roof by footprint, but if you click the drop-down button next to it, you'll see the other options and in this case roof by extrusion is the option that we want. Now that will display the work plane dialogue and you've got a few options here.
If we had some named work planes in the model like grids or reference planes, we would be able to choose them here, but I don't have any in this case so I'll choose the default option here of pick a plane. When I click OK, this will allow me to select a surface of any existing object so I'm going to actually click the surface of this brick wall and that will make that the work plane. Now even though I have established a work plane, Revit still needs to associate the roof object with a level so it will offer me a choice of the two levels that are in this project: level one down here and level two here.
I think level two seems the most logical so I'll go ahead and click OK on that and now I'm in sketch mode. So at this point, you can use any of the sketch drawing tools you want to draw the shape of the roof. Now in this case I'm going to make sort of a curved form. So I'm going to choose the start and radius arc and I'll pick my first point maybe right about here, draw it up at a slight angle. Now I'm setting the radius and I'll just kind of make a slight curve like that. Then I'll make another point maybe over here and I'll kind of pull it down until it snaps tangent to the first curve.
Now you don't have to draw exactly the same shape that I'm drawing, just something like that, but I'm going to click the modify tool and the important thing to understand about the extrusion roof sketch is unlike all the other sketch objects that we've looked at so far in this chapter, this is an open curve so you only need to draw, even just a single segment would be fine, but you can draw several connected segments, but you do not want to join it back on itself. The reason for that will become evident when I click Finish here because what it does is it actually creates the thickness of the roof based on whatever roof type you have selected so in this case it's generic 12 inch roof and I'm going to make it a little bit thinner.
I'm going to go to the generic nine inch roof, but do you see how the thickness is being controlled by the type? So the only thing that it's getting from the sketch here is the curvature. Now it looks a little bit strange, especially when you deselect it because the bricks are showing right through. So let's go to 3D view to understand what's going on there. I'm going to do that on the project browser. Expand 3D views. Double-click the curly bracket 3D and of course you could use the default 3D view tool here as well and what you'll see is that when you do an extrusion roof, Revvit guesses how far to extrude it based on the context of the building model.
So in this case it saw the depth of the overall building and it just used that as the depth of the extrusion. Now if I click the roof, you can see that it has an extrusion start, which is at zero and an extrusion end which in this case is -45 feet. So it just did it project it back in to the building. Now there's a couple ways you can manipulate this. You can use these small grips here and stretch it and I'm going to stretch this end all the way outside the building and now it's kind of floating away from the building, which may be my design intent, but now I want to kind of make those numbers a little bit more rational.
So for the extrusion start, it's now nine foot nine so I'm going to make that 10 feet and then for the extrusion end, I could set it to zero and that would pull it in to the work plane or you can actually use the align command right here in 3D. So when I go to align, notice that I'm able to highlight the face of the wall and then I can highlight the face of the roof and it will snap right to it. Now if I were to select the roof, you'll see that actually made it zero so it's really up to you which method you want to use, but that gives me this nice little free form curving roof here.
So an extrusion roof will have a straight extrusion along some distance that you can set numerically or you can use those grips and the shape of the roof is something that you sketch using the typical sketch mode tools.
First, get comfortable with the Revit environment, and learn to set up a project and add the grids, levels, and dimensions that will anchor your design. Then author Paul F. Aubin helps you dive into modeling: adding walls, doors, and windows; using joins and constraints; creating and mirroring groups; linking to external assets and DWG files; and modeling floors, roofs, and ceilings.
Paul also shows advanced techniques for modeling stairs and complex walls, adding rooms, and creating schedules. Finally, discover how to annotate your drawings so all the components are clearly understood, and learn how to output sheets to DWF, PDF, or AutoCAD.
- Understanding BIM and the Revit element hierarchy
- Navigating views
- Creating a new project from a template
- Adding walls, doors, and windows
- Adding plumbing fixtures and other components
- Linking AutoCAD DWG files
- Rotating and aligning Revit links
- Working with footprint and extrusion roofs
- Adding openings
- Adding railings and extensions to stairs
- Creating stacked and curtain walls
- Hiding and isolating objects
- Adding rooms
- Creating schedule views and tags
- Adding text and dimensions
- Creating new families
- Using reference planes, parameters, and constraints
- Plotting and creating a PDF