Ok so, I am building a home, and have been pretty excited about it because I really like how it's coming along. Now, I've gone to place a roof, and it won't let me, because it says my rooms are not enclosed? All the walls are together where they need to be...So I don't get it. I can't place the flat surface room things either, it just tries to drop them in the middle of the room downstairs.

I don't want to have to scrap this house, I've been working on it for hours. Anyone know what I am missing here?