Hey guys, this is a strange one.
I enabled all 2 sided options I could find. Lighting is blocked but my roof itself doesn’t receive lightmass baking.
When I do the opposite, my roof receives shadow from the inside, but the light penetrates the room…
??? Can anyone tell me what I missed? The LightingTroubleshootingGuide didn’t offer me clues.
I believe “Use Two Sided Lighting” is intended for things like paper and foliage, and not walls. I’m not sure if use two sided lighting even bakes unqiue lighting for both sides of a mesh, which you would need for a mesh like that. With lightmass, it’s typically best to avoid meshes that don’t have any depth and aren’t closed off, especially for walls.
Just make mesh that has some wall thickness. I also think that lightmass was not designed to handle all those weird cases.
Yeah I stopped trying 
I just added a shell on every roof and the problem is fixed. Gives me extra polygons but it ain’t too bad.
