Always get the outer faces of walls


I’m trying to create a definition that gets the outer face of walls from a revit project. Hopefully if this works, I’ll be using it to place a wall based family on the outer faces of the walls.

I came up with this definition but I’m stuck at a point, I don’t know how dynamo organizes surfaces in a list and I can’t find a way to always get the outer faces of walls.

In the picture below, I’m red tagging what I hope my definition could produce. Can anyone help please? Thanks.

you could use package to grab the wall’s EXTERIOR direction and then shoot a point from wall’s mid point in that direction. Now, if point is in a room you are targeting that means that wall’s Exterior is facing into the Room, otherwise outside of it. You probably noticed that surfaces in a wall geometry collection are organized in a certain way. That means that wall on exterior face is always #4 and wall on the interior face is always #2 (the actual order might be different but it should be consistent). I think you know where I am going with this. Instead of sorting walls by area like you are doing, i would leave them be - they already have an order - use that order to extract exterior facing surfaces. Archi-lab package has a node for collecting room’s boundary walls so you can use that as well.

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I have tried what you said, I can now see the exterior faces of each wall, so how can i extract them? any suggestions?



Hi Tarek,

There is a custom node called “Surface.FilterByOrientation” from “Clockwork Package” use that node to get outer faces of the walls. You can also use that node to get inner, upper & bottom as well. Good Luck!



Thanks alot, this is what I was looking for :slight_smile:



Thanks for providing this graph. I’m having some trouble getting purely the outside face. I am getting the outside face of the walls but when it turns the corner it gets the inside face. In other words it is getting the exterior of the wall but not the exterior of the building (see image). This is causing and incorrect area calculation. If working, this would be useful for code related issues like Spatial Separation and Wall to Glazing Ratio. I know many have been after this but has anyone been able to calculate the exterior face walls with consistency and accuracy? On other words, should I spend time on this or will I fall into a vortex of vectors and normals?

A possible solution.

Tried it and it works! Wow, didn’t think this was possible. Thanks! I’ll keep using it and let you know how it goes.