In the winter time, our ceilings seem to lift off of the walls creating a gap between the crown molding and the tops of the walls. As summer creeps nearer, the ceilings settle back onto the walls. If we caulk the edges, come winter time, the gaps reappear. What could be causing this? My husband thinks it might have something to do with the heat in the attic and the roof not being vented properly. Thanks for any help We live in central North Carolina.