Garage/Attic insulation dilemma
I’m finishing an 896 square foot garage in SW Washington (zone 4C) that has in-floor radiant heat. It has a 10’ ceiling built with attic trusses and therefore a 12’ x 32’ inhabitable space running down the center above the garage which we plan to use for heated storage.
I have already insulated the attic space to R-31 in the ceiling (batts and foam board) and R-21 in the sidewalls. I plan to insulate the garage and would like to use the radiant heat to keep the garage at between 55 to 65 degrees for working during the winter months.
Because of the heated livable space above and the moderate temperatures planned for the radiant heating in the garage, I’m unsure if I should insulate the entire ceiling to R-30, the ceiling below the inhabitable floor space, or just the ceiling of uninhabitable attic space. In any case, my intent would be to have the vapor barrier to the winter side of the inhabitable attic space and to the winter side of the garage in the uninhabitable attic spaces.
Any recommendations are appreciated.
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