Adding Exterior Polyiso Foam Insulation to Zip Sheathing
I am currently building a home employing some techniques I’ve learned here. For insulation, I put R20 closed cell under basement slab and garage slab, R20 continues up basement walls where it meets ZIP R6 that is on all exterior walls and roof. In order to put the R6 on the roof, I unfortunately had to first put an entire deck of OSB down so the ZIP R6 would not compress on the rafters.
Now for the terrible part. I didn’t put the R6 on the the entire front wall of the home because I am putting a natural stone veneer on the front of the home and thought the R6 ZIP would have posed problems, so I put up regular Zip instead. This has bothered me immensely the whole time since I went through the trouble and spent a lot of money creating an entire circle of insulation around the home to avoid thermal bridging. The ZIP Huber rep stopped by my house and informed me that the R6 insulated sheathing can indeed support natural veneer stone. I beyond frustrated that I wasn’t smarter earlier. So now I need to put insulation on top of the regular zip wall that is on the the entire front of home. Do I put R3 ZIP over the zip, or put a piece of 1″ insulation right over the zip. I am worried about condensation. I can only add 1″ of material which is why I can’t put R6 up. Is R3 over zip going to create a swampy mess with condensate since it might not be able to dry to inside or outside since this would be literally a Zip sandwich? a ? Will putting up 1″ of rigid insulation be better so that it can dry to the outside?
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