Collision within a building

Hello,
I have got a model of a small building which I imported from blender with flipped normals, so that you only see the inside of the building.I have also got a player, with a collider and rigidbody, which can move. My question is what is the best way to add collision between the building and the player, i mean the floor and any wall within the building. Should I make tiny colldiers for every wall or how should I do it?
Thanks!

hi, for performance reasons, if you have very complex meshes, its recommended to use many little box colliders, take a look how is bridge done in boot camp demo… what i do in such cases is to create various empties and apply box collider to each one and place in their respective places…

this works great, unless you want to do a fighting game… that is a bit more complex…