probably such a stupid question but I have a basement drawn out with walls in place. I want to draw a ceiling (rectangle across the whole thing) and then pull it up 10". However, when I draw the rectangle for the ceiling all of the walls below "intersect" with the new face. Then, when I pushpull up on the ceiling to extrude it 10", it leaves holes where the walls below are. I'd like this face to be independant somehow if possible. Is there a way to do this or am i missing something obvious?