Parts of BSP Brush disappearing

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:

How can I fix that?
Thanks in advance.

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 ? :wink:

I made one other staircase , doing the same thing and it worked fine.


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.