My house is a cape so the 2nd floor has Inclined Ceilings. I noticed that when it rains a lot the ceiling bubbles, like a thin layer pops out. Then when it gets dry it all goes away. The house is from 1951, I don't know when that ceiling was installed, it could have been in the 60's. So I was thinking I install my paint guy to install a thin layer of drywall on top of it? I would replace it, however I recently had blown in insulation in the attic space (above the ceiling). So I can't remove it. Thanks!