Get geometry of void from family instance


I am working with some window family instances inserted into walls.

I would like to ask if its possible to extract the geometry of the voids defining the window cuts?

I need this void geometry just inside the Dynamo space for now.

Best Regards,


Might be easier to ask the associated wall for the opening in the area of the window.


Thanks for the reply.

This is the particular case I have:

I am wandering if i can get this shape - the void I traced with red lines in paint :slight_smile:
I would just highlight it in the project file but its impossible so I had to use paint.

I tried something in the spirit of what you suggested but this node setup does not give me the the shape of the void(s).

(The “Element.Iserts” node I’m using is from the Clockwork package.)

I think that the family works in such a way that these voids do not exist in my Revit model in the first place. They exist as geometry in the family file but It seems as they don’t my Revit project file.

Maybe in the family settings I can define them to exist(be highlight-able) in project files?




I managed to generate the shape of the void cut:

I basically used some boolean operations that can be also applied to a large number of walls and windows.

With the following script:


TBH this method feels a bit workaround-ish to me. If the geometry is already defined in the window family, dynamo should offer a better, more straightforward, way of extracting its shape.

Thanks for the hint :slight_smile:

Best Regards,


This was effectively what I was hinting at.

Yes, but I believe that it is the Revit API which needs to add this functionality not Dynamo. To make things simpler you could make a simple custom node of the many nodes required to get the shape you’re after.

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I agree.

Thanks for the replies!

Update #2:

The method works OK until you stumble upon a model that gives one of the classic Dynamo errors (when generating the wall geometry) “trim_with_edge_loops…”:

In this particular case I’m not sure which wall geometry is causing the problem but i have some overlapping voids in some of the wall walls. (Some of which cut the walls only halfway trough its thickness.)

Judging from the open status this issue, I am not sure this is currently solvable -

My workaround is to use this node to avoid the warning and filter out those “null” walls (“Geometry+ “ from Clockwork):

After this ill just use the window bounding boxes to represent the inserts in the “null” walls.

Actually, I’m doing all of this because I have some issues with parts creation.

I suppose that whatever is causing the “trim_with_edge_loops…” problem is also causing this problem:

So, before we get more “window void” functionality from the Revit API, I find that it would be even more usefull if Revit gets a more robust “Make parts” command and Dynamo improves the Element.Geometry node. I’ve had problems with the Element.Geometry node in other scripts also.

That said, Im sure that’s no easy task.

I am using Revit 2019.2, Dynamo Core ver and Dynamo Revit ver

I haven’t tried newer versions.

Are my issues with these functionalities already improved in newer versions?

Please excuse if that’s the case.

Best Regards,