I use to notice, after putting the roof on and then going inside, even in build mode or live mode, it was all open and no ceiling :)and when I went to the floor section, and did the angle thing, there was no grid to put the tiles on the ceiling. So what I did, is click the roof down one click until you see the grid from top view. I would put the cheapest flooring down and then go into the house and level it out and then you can see the ceiling. I was able to put any design I wanted at that point for my ceiling. If this doesn't make sense, you will have to excuse my explanation this morning, only one cup of coffee so far. I can do screen shots, but that is the way I do it anyway.