getting original geometry volume for structural framing from API

[natanatalili]

Hi all

I would like to get the original volume for concrete structure framing which are joined to structural slab from API.

I tried snoop a selected Structural framing element in a 3D view using Revit Lookup and i can successfully get the original geometry volume.

However, when the structural framing are connected between column/wall, I found that the original geometry volume is not correct.

Below images are the capture for the section views of those cases, showing the volume that I get from Revit Lookup and the expected volume which I calculated by hand.

I wonder why the original volume taken from Revit API is different from my calculation by hand?

Thanks