How to get the external and internal face of individual walls with many inserts

I have several walls with many inserts, so there are many faces for each wall, and I can not use the list index to filter the faces because the face lists will have variable list members.
Could you kindly guide me about how can I get the exterior and interior faces of each wall?

I do appreciate your help and time in advance.


You need to first tell us what you would qualify as “internal” and “external”. Compared to what? A room? An element? We need more information.


Hi @Nick_Boyts
Thank you for writing back. What I meant is the Revit’s default external and internal faces for the family.
If we draw a wall clockwise then the exterior face of the wall is always pointing outside, in other words where you get the flip icon is the default exterior face of the wall in Revit.

Then that might be the best way to determine the interior/exterior face: via the wall direction. You would then also have to check to see if the wall faces have been flipped or not.

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Hi again,
Thank you again for your input.
How can the direction of the wall help me? I am a bit lost here! I can get the line direction but I don’t know how to check if the was is created in clockwise direction.

The direction would tell you whether it was drawn clockwise or not. The exterior face will always be the left side of the wall’s drawn direction (assuming it hasn’t been flipped).