I've asked around and got conflicting information. So here is what I think. We didn't involve any licensed professionals or municipal bureaucrats in the construction to date. It's possible that if we were subject to a building department inspection walls would have to be removed or modified. I expect this to be true for the ceiling as well. Obviously we have been willing to take that chance so far and I am willing to extend that risk to the ceiling. If it happens, we will deal with it, in the meantime we will enjoy a nicer space. In addition I believe the more complete the area is the less likely a fire inspector will be to call in an electrical or building inspector. I asked Leroy about it, he didn't seem to think a fire inspector would care.