Depends on what you are colliding with. Pick one to func_wall. If its a complex design, used func_wall in connecting brushes... e.g. flanges in a pipe.
like so
========= pipe =========| pipe into wall
change to
========[]| flange in between, which is a func_wall
and i believe both are cut up if one isn't func_wall'ed
Comments
like so
========= pipe
=========| pipe into wall
change to
========[]| flange in between, which is a func_wall
and i believe both are cut up if one isn't func_wall'ed