There is a bug *most likely the creators already know about it* where player made roofs don't disappear when you are inside and I think the reason this glitch happens is because most roofs in project zomboid are slanted so it counts it as a ground floor so thats why it doesn't disappear. its pretty annoying when your a creative player trying to make a awesome base and come to realize the roof/2nd floor isn't disappearing so placing down stuff inside is nearly impossible.