Maybe I've don't understood correctly.
What I want to say is this:
The roof is outside the room (yelow).
Or maybe you refer to point 3.3 from the mini-tutorial where I've explained a possibly use of reverse faces.
For my curiosity: can you share the last roof object?
----------------------------------------
A computer program does what you tell it to do, not what you want it to do. Murphy's Law
When all else fails, read the instructions. Murphy's Law
If you don't like "AS IS", DIY. Dorin's law
