I tried searching past threads but came up short. I have old cellulose in attic, and want to increase insulation. Ceiling is sheet rock over plaster. I can get a good price for soem rigid foam, but if I apply that perpendicular to the ceiling joists, will I trap moisture underneath? I could leave a small gap between boards, and not get that much air infiltration ( convection) Thanks.
No announcement yet.
Rigid foam over cellulose