Zip wall insulation ratio question
I am considering using insulated “Zip System R-sheathing” on a project to save some labor$$. From a building science standpoint I am somewhat unsure. I am in Zone 7.
Ideally, I would have something in the neighborhood of a 2/3 out to 1/3 in or 1/2 out to 1/2 in insulation ratio to avoid condensation problems. The Zip wall product places the foam (1 1/2″, claimed R-6.6) on what at first glance seems to be the inside of the wall plane….so theoretically on the “wrong side” with regard to the ratios (more stud cavity insulation).
Or is it perhaps okay due to the hydrophobic character of the bonded insulation being the (hopefully not) condensing surface?
Long story short: Anyone have any input if this would be a safe wall assembly (2×6 w/blown in glass or cellulose w/ R6.6 Zip R, rainscreen outside, all taped obviously)? I am trying to achieve something in the neighborhood of R 30, maybe R-35.
And….has anyone sprayed closed cell foam against the foam of a R Zip panel (chemical compatibility)?
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