You could call it the $6,500 problem, because that’s what it’s going to cost Kacey Zach to re-insulate a cathedral ceiling with closed-cell polyurethane foam and hang new drywall.
Writing at Green Building Advisor’s Q&A forum, Zach explains the situation: a cathedral ceiling framed with 2x12s and insulated with fiberglass batts to R-38 “with no regard to air sealing.”
The result? Nasty ice dams where two sections of roof intersect. “I’ve gotten quotes to spray foam the ceiling to R-38 with closed-cell foam for $4400,” Zach writes. “I also got quotes to re-drywall the ceiling after it is all done for $2k. I could be into this project for nearly $6500…yikes! Do I have any other less costly options?”
That’s the subject of this Q&A Spotlight.
Despite the cost, foam is the best option
Even though the closed-cell foam isn’t cheap, GBA Senior Editor Martin Holladay thinks it’s Zach’s best bet for curing the problem.
“It can be installed from below — a job that will require new ceiling drywall — or it can be done from above — a job that will require new roofing,” Holladay says. “If your current bids seem high to you, you can always contact other contractors for more bids. But I wouldn’t be surprised if the job ended up costing what you were told.”
Zach thinks the foam will be between 6 inches and 7 inches thick, and plans on filling the rest of the cavity with R-19 fiberglass batts. In order to spread the costs out, Zach wonders if it’s OK to leave the insulation exposed for the winter and tackle the drywall later.
Unfortunately, that’s not an option, Holladay says. Exposed foam is a fire hazard that must be covered with…
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