Foamboard and WRB for Unconditioned Enclosure
Cold edge of Zone 4. See picture of 600 sq ft unconditioned walk-out storage space/proposed art studio (no further finishing) under suspended garage. Stays cool enough in summer with portable dehumidifier connected to floor drain. For most of winter, with indoor temps usually 40-50F, a space heater should be sufficient when using as art studio. During severe, sub-zero cold period last winter, did drop to around freezing inside, but a rare occurrence.
Walls are 12 ft high, about 50-50 concrete-wood framing. You can see R-26 blown-in walls. I’ve read here that fluff need to be closed in to be effective.
While I would like to put up foamboard, the fire-rated stuff is very expensive and usually special order. Would a vapor barrier, such as Tyvek work? I see Tyvek is Class A fire rated, which I think means it’s as good as you can get for a wallcovering. They make Tyvek FireCurb in Europe. It’s self-extinguishing with other fire features.
Also, notice the bare steel I-beams at top of walls. No insulation at all. I’m thinking I should wedge some foamboard into the beams. Would this be best? Thanks.
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