Hello,
I am trying to make a road using BSPs however something rather odd is happening with them. If I remove faces of a BSP that I don’t need (bottom, sides, etc) and I place another BSP next to it, it will interfere with the one next to it or with itself, making some parts of the BSP disappear like so:
havent seen that one before. but id recommend not deleting faces, instead use subtractive brushes for areas your trying to have free space
I’m having similar but different issue:
Created spiral case, extrude bottom faces to grow downwards a bit, but on build for this level, result was no visible front face, only left right and back are visible, as seen below:
What would cause this ? 
I made one other staircase , doing the same thing and it worked fine.
thx
I could not do this by choosing multiple faces, yet individually one by one, I was able to extrude them all just fine for desired outcome.
thx
