Moderating temperature swings in an unconditioned attic
I have a decent-size walk-in attic accessible through a weatherized door. The air barrier and 15 inches of cellulose insulation are installed in the cavity between the attic subfloor and the dropped ceiling below. Thus, the attic is outside the thermal envelope of the house.
We actively use the attic space for storage, but my wife dislikes the large temperature swings of the attic. In zone 5, the temperatures can range from well-below freezing to squelching hot. My wife worries about the impact on some of her more sensitive belongings.
I really don’t want to bring the attic into the conditioned space. That would mean moving the air barrier and insulation to the roof deck, either above or below. Aside from the expense and work involved, the total heat load for the house would go up substantially.
My question: Can modify the attic space to make it “moderately conditioned,” with temperature swings from say 50 to 80 degrees or so. I thought about sealing up the vents and installing fiberglass bats between the rafters and wall studs. The primary thermal and air barrier will remain at the attic floor.
Am I creating a dangerous situation?
I also thought about installing reclaimed polyiso insulation to the undersides of the rafters. This would allow the roof sheathing to continue to be vented.
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