Dense-Pack Cellulose Cathedral Ceiling
My roof (zone 3B) needs insulation, but between Martin’s concerns and the inexperience of the contractors in this market, I am conceding that 5″ of polyiso foam isn’t going to happen. I think that 3.0″ nail base (R15) can though (with taped seams). I’d like to get closer to the code minimum of R30 for the assembly. I would rather not tear out the finished interior vaulted ceiling (cedar shingles on battens on felt paper, I know, strange), but the lousy interior air barrier (i.e. the felt paper) concerns me. Given that 4″ of dense-pack cellulose is air permeable, how big of moisture risk would I be taking in this climate with this assembly?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part