Hi, I'm working on a mod that adds a new dungeon to Skyrim but I'm having a problem with collision. I've found tutorials on how to add collision to objects, but none of them cover internal architecture like hallways and rooms where the normals face inwards. They only cover convex objects.

I tried using chunkmerge to duplicate my hall geometry and followed the nifskope tutorial to the letter, but when I shoot arrows into my custom hallway they only collide with the ceiling, I pass through the walls and floor. I looked at the collision data in the CK by previewing my mesh and pressing F4, and it is mapped onto the geometry perfectly. Yet, the collision for the walls and floor won't work. Has this happened to anyone else? Any ideas how to fix it?