Attic Insulation Overhaul

Old 08-26-22, 08:49 PM
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Attic Insulation Overhaul

House is colonial in central Massachusetts. 30x40 with a 10' peak in attic. I am installing a new attic based heat pump with electric strip heater to service 2nd floor. Current insulation is 6" of fiberglass batt that is 40 years old. I am leaning towards a hybrid approach. I am currently mitigating an attic mold problem. I want to encapsulate with 2" of closed cell foam in the 2x6 rafters. This will ward off future mold and make the attic a conditioned space helping the new hvac. Then the diy kicks in. I was thinking of filling the remaining space in the 2x6 rafters with 3" of rockwool then hanging 2 to 4 inches of foam board over that. The alyernative would be to fill the rafter bays with foamboard. I was thinking rockwool would be easier because it could be compressed some if the sprayfoam thickness was irregular. Thoughts on either approach? Should I involve foil facing somewhere? Do I have to cover foamboard with sheetrock because of fire? Are there any foamboard products that are fire rated? Let loose and shoot holes in anything I may have said
Old 08-26-22, 09:00 PM
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I don't think you need to cover the foamboard in an attic (not living space and the drywall ceiling below is the 1/2 hr fire barrier) but with the mechanical up there they might require it... you would need to check with your local inspector to be sure. But yes, Thermax is a fire rated foil faced foam you could consider... along with their foil tape on the seams. Use that and there should be no problems either way.

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