Revit Architecture: Roof by Extrusion

In this Revit Architecture tutorial, I show you how to create an Extruded Roof form using the “Roof by Extrusion” tool.

For the purposes of this tutorial, I am going to use the following simple building model on which to create our Extruded Roof…..

 

OK, let’s begin. Switch to the “Architecture” menu and choose “Roof”. When the drop-down appears below this tool, choose “Roof by Extrusion”……

 

 

Now just before we go any further I want to explain exactly what we are using the “Roof by Extrusion” tool for. This tool allows us to sketch a 2D profile in an Elevation (or Section) View and then create a horizontally-extruded view from it. The first step in this process is to choose a plane on which we are going to sketch the 2D profile of our Roof. When the following panel appears (straight after you have selected the “Roof by Extrusion” tool), make sure that the “Pick a Plane” option is active. This will then get Revit to detect the various planes it finds as you move you cursor around in the active view…..

So in a 3D View I can hover my cursor above the model and Revit highlights the various planes that it finds. I am going to use the end of the building as the plane on which I will sketch the 2D Roof Profile. You can see in the image below the end wall highlighting in blue as I hover over it……

 

Go ahead and select the plane you wish to sketch on. As soon as you do this Revit then brings up another panel….

 

This panel is allows you to choose the Level that you want you Roof referenced to. It also allows you to apply any offset to the height of the Level. Both of these parameters can always be changed afterwards, so don’t worry too much about your choices at this point.

With your working plane set and your choice of Reference Level made it’s time to start sketching the Roof Profile. Revit switches to Sketch Mode at this point- the good old “Green Tick and Red Cross” confirms that you are now in Sketch Mode…..

 

 

You now need to choose the drawing tools you are going to use to create the sketch profile. So referring to the above image: Choose a tool from the draw palette (1) and then sketch the Roof Profile in the active view (2).

 

 

 

In the above image you can see that I chose the “3 point arc” tool and I have drawn a “wave shape” as my Roof Profile. PLEASE NOTE: You only sketch the shape you want for the TOP of your Roof. You do NOT create a closed loop. You do NOT sketch around what will be the perimeter of your roof in section. In the above image, the profile you see (2) is the COMPLETE profile for this roof. I say again, do NOT create a Closed Loop- Revit will not accept it for this type of sketch. When you are happy with your Profile sketch, go ahead and hit the Green Cross. This will instruct Revit to proceed and create the 3D geometry for your roof form…..

 

 

 

In the above image you can see the roof geometry in Elevation. Notice how the roof is “built down” from the profile sketch you created. You can change the Roof Type at any point- but the upper surface of your Roof Type will always be coincident with the Sketch Profile.

 

 

In the above image we can see our Roof Form in 3D. So far, so good. But if we take a look at our roof in plan…..

 

 

…we can see that it is a pure rectangle and does not follow the perimeter of the building. This is because it is a simple extruded form. However, we can make it follow the building line by “notching out” the areas we do not want- 1, 2 and 3 in the image above.

 

 

 

To cut away at our Roof form in plan, first select it. You will now see some Editing tools on the Ribbon. Go ahead and choose “Vertical” on the “Opening” panel. If you can’t see this tool it is probably because you do not have the roof element selected.

 

 

Once you have activated the “Vertical (Opening)” tool, choose a tool with which to sketch the opening profile. I am going to use the Rectangle tool (1, in the image above). Then sketch the areas that you want to cut out of your roof. I have sketched 3 separate rectangles (see “2” in the above image). It does NOT matter that these rectangles overhang the original roof form in plan. Go ahead and hit the Green Tick to get Revit to create these Vertical Openings (you can also think of them as void forms). Here is the resultant roof form in plan…..

 

 

If we switch to a 3D view we can see that the walls under our roof do not yet meet its underside…..

 

 

 

We can easily rectify that by the use of the “Attach Top/Base” tool…..

 

 

First you need to select the roof element (1). Then choose “Attach Top/Base” on the Ribbon menu (2). And finally select the element you want to attach to- the Roof in this case (3). You will now see that this wall neatly meets the underside of the curved Roof….

 

 

Notice how this only worked for the single wall that we selected. Note (in the above image) that the adjacent wall does not yet meet the roof. So you have to perform the above process for all the walls that are situated beneath the roof form. Thankfully you can do them all in one go- just put a selection fence around your model and then use the “Filter” to select JUST the Walls. Now you can attach ALL you walls to the curved roof in one go.

Key Points

  • The Roof by Extrusion tool is used to create wave form type roofs
  • You create a sketch of the upper Profile of your roof in a side view (i.e. Elevation of Section)
  • You can select a Reference Plane to sketch your profile on- as long as you have a NAMED one in your model
This tutorial is taken from "The Complete Beginner's Guide to Revit Architecture" FREE online course.
This tutorial and over 80 others are available as a PDF Ebook. For details please Click Here
Posted in Autodesk Revit.