UNIONS: How do I fix this bug?

I’m attempting to make a door using unions, at the start it’s all good. When I play/test the game I cannot go through the door. How do I fix this instead of using collisions?

Union hitboxes are always messed up on roblox.


I don’t use Union because they all way’s mess up try looking up after way to do it or just keep trying until it work’s can I see how it looks when you test it and see the Union and how you use it? I may help if I can see how you use it.

If i were you i would only get into the habit of only unioning things that players aren’t walking through such as doorways, hallways, tunnels, blah blah. Using standard parts vs. unions won’t yield any insane performance either. If you are just using negated parts to union a hole in the wall then thats just not really good practice and doesn’t really give you alot of control of your build. Its more-less a shortcut. On a side-note, i think there are plugins to see the hitbox’s of unions. Something like “Decomposition geometry”. Not 100% sure.


Unions don’t handle concave shapes well. The collision geometry is simplified to improve performance. You’re recommended not to use unions for purposes like this.