Covering popcorn ceiling
We have a popcorn ceiling in our house with a cathedral ceiling. We would like to cover it with 2″ foam insulation and sheet rock over the insulation. We only have a 4″ of insulation above the current sheetrock and have a 2/12 pitch roof. Will this be a potential problem for condensation or mold?
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Q. "Will this be a potential problem for condensation or mold?"
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If you have 4 inches of fiberglass in your ceiling now, it has a nominal R-value of about R-14 (but it is probably not performing at that level).
Two inches of polyiso have an R-value of about R-13 (but the polyiso would likely outperform the fiberglass batts by a considerable margin).
Even in the warmest U.S. climate zones, building codes require a minimum of R-30 ceiling insulation. If possible, you should install more than 2 inches of rigid foam.