I have 3+ car garage with a second floor that I am finishing off as living space. The space has kneewalls ~5 feet high, and I am trying to determine the best way of insulating the attic space/kneewalls. From research I’ve done, most seem to agree that the best solution is to insulate the roof rafters (bringing the kneewalls into the thermal boundary), as opposed to insulating the kneewalls themselves. In my scenario, since the living space is above an unheated garage (which has R-19 in the walls), I have already insulated the garage ceiling/2nd-level floor with R-30. One other factor that I’m not sure of it’s impact – there will be a small hvac system (gas) in the attic space to heat/cool the living space.
While I would be able to insulate the attic rafters in my scenario, wouldn’t I lose a lot of heat through the uninsulated kneewalls into attic space? So in addition to insulating the roof rafters in the attic, could I also insulate the kneewalls? All of the articles I have read on this give an either/or scenario, but none has mentioned doing both as a possibility. Where I live (upstate NY), I am most concerned with impact on heating, and not cooling.
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