Us technical consultants just love being put on the spot and that’s exactly what happened to me this week whilst onsite (Thanks – you know who you are!)
The issue: in Revit, the standard windows all have a single size opening; Interior and Exterior structural openings are the same.
My client works with a certain hotel chain whose windows have a smaller external reveal so that the outer brick creates a weather seal. Also, they need to annotate this, so it’s not just a case of popping in a schedule reporting parameter with a formula - it needs to be modelled.
Create a new window using the standard window family template.
This will give you a generic piece of wall and an already placed opening, controlled by a few dimensions.
Now delete the existing opening. The reason for doing this is that the opening object always cuts through the entire wall – you can’t lock its cutting depth to reference planes and control it with parameters.
Place reference planes and dimensions driven by parameters to control the inner and outer reveals (test them to ensure they work correctly). In this example I am not modelling the actual window geometry so you can easily see the process of what’s happening.
With that done, switch to the Elevation Interior view and create a Void Extrusion (Create tab> Forms> Void Forms> Extrusion) to be locked to the reference planes defining the internal opening.
In a plan view, drag the void extrusion so that it snaps to the inside of the wall, and the refence plane defines the reveal depth. Lock both faces in place.
Repeat this for the external opening.
Now use the Cut Geometry tool (Modify tab> Geometry> Cut) to remove both void extrusions from the wall.
You should now have something like this:
Test the controlling parameters to ensure that both openings behave as required. If they do then you can model the window geometry and add any 2D detailing etc.
Hold on; why delete the original opening and not just add one void instead I hear you say?
Well, because you can’t have an opening and a void in the same family. Revit wil let you get all the way to cutting the void from the wall before it tells you.
Before saving your new window family, make sure that you check the Cut with Void When Loaded option in the properties.
Load into your projects, and voila:
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