Insulating a cathedral ceiling without disturbing plaster

Questions, answers and advice for people who own or work on houses built during the 20th century.

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Joined: Fri Mar 09, 2018 3:45 pm

Insulating a cathedral ceiling without disturbing plaster

Post by MHDashwood »

I just received a quote for insulating the second-floor cathedral ceiling of our 2000 sq. ft. 1951 cape cod: $14,000.
Anyone else done a project like this? Was this in the ball park for your costs?

The proposed plan involves removing a 1' x 30' strip of plaster on the ceiling and injecting closed cell spray foam. The cost estimate includes removing the plaster, removing existing insulation, and disposing of all that. And then, injecting the foam and then replacing the removed plaster with drywall and mudding. Sanding and painting would be a separate expense.

Closed cell is a good option in our climate (upper midwest) where summer humidity and ice dams are major problems. But I am shocked at the cost of this estimate. At this price, I can't imagine that this is the best use of our (limited) resources. If we are committing to spending this kind of money, aren't we better off going in from above? For example, removing, injecting the foam, and replacing the roof deck with better insulating materials? Or is that even physically possible? The insulation company seems to be concerned about working on our rooftop, despite the lack of a strong roof angle (it's about 2/12 or 9.46 degrees). But they haven't clarified exactly why they are proposing this course of action.

I'm also going to call a roofer we trust to get a "second opinion" but I thought this community might also have helpful ideas. Thank you.

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