Blender Plan Made Into Level Walk Through Walls

Hi guys, I am having some issues with a blender model I made of a level built from a plan.

When it is in unity I can walk through the walls, not all of them but some of them. My player is a unity cube at this time, nothing changed just a rigidbody and a script.

I have toggled Generate Colliders on the mesh, this has made it so I can walk through some of the walls and not all of them.

I am not sure what it is that is making this happen.

Trying to get this fixed save so much time!

Make sure your mesh has all the faces pointing the right way. Having them flipped will result in you being able to pass through it. Also, add a “Mesh Collider” to the object. It’s good for buildings.