Options to insulate a cathedral ceiling
I have a friend who is converting a attatched cariage house to a finished living space in the Boston area. The second floor is wide open with a cathedral cieling framed with true 2×6’s. The rafters rest on the wall plate abought 4′ off the floor and the ridge is abought 16′ above the floor at roughly a 12/12 pitch. Each floor measures 17×26. My friend understands that he needs greater depth in the rafters to get the nessasary R value and figures he needs to sister new framing to achive this. My question is could he spay foam a couple of inches followed by dense packing the remainder, AND THEN attatch ridgid foam board to make up the R’s needed on the underside of the old joist’s? Followed by drywall or beaded paneling. Or would it be cheeper to just frame out to the desired depth.
Replies
He could spay foam the whole thing( 5") and get a R-35, not sure on the cost in your area but it would be easier. I'm not sure on the dense pack and foam board idea. What I don't like about it is screwing the GWB over the foam and if it would float out nice or not.
To answer your question though I think furring it down would be cheaper but more of a pain.
Dave
Spray foam the whole darn thing full, without a doubt!
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