HAMMER: Strange glitchy geometry

I’m currently making a Map for my Garry’s Mod gamemode, and I created a whole in a roof but a piece of the roof remains? I can’t see it in Hammer and it has no collisions in-game. If anyone could help me remove or at least identify what it is, that would be great.

( http://imgur.com/a/s67KW )

i’m guessing you clipped the brush to make the hole, use multiple brushes and vertex edit the shape to make the hole :slight_smile:

Post a picture of the same area from hammer, with the brushes around the hole selected.

I ended up just deleting the whole roof and making a new hole. Works great now. That was pretty weird though.