Insulating an Unvented Cape Attic
Hi! I’m looking for some advice on insulating a 3 story home built in 1905. it has a finished 3rd floor with a cape cod, unvented attic and an original tile roof. We’re in southern Ohio. The unfinished space on the 3rd floor has flooring (no open beams) and knob and tube under the floors. there is no knob and tube in the knee walls or the space above the 3rd floor.
My question is how should I insulate? I have a quote to blow-in across the unfinished floors (but then I lose storage), batt the knee walls, and across the 3rd floor ceiling. I have a separate quote to use 2″ of closed-cell foam to vapor seal the attic rafters and then across the 3rd floor ceiling, with batts/blow-in added for r-value. I’m told since it’s unvented and it’s closed cell, this will not create issues for my roof decking. The quotes are surprisingly not that different in price.
Any recommendations on which way to go? My priority is clearly to save energy/comfort inside, though I also do not want to compromise an original tile roof by rotting the roof deck (though closed cell seems ok in this setting).
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