Outsulation hits a road bump: 1/2-inch polyiso sheathing
So I had my entire plan laid out, for an exterior crawl space insulation. Excavate to footer, waterproof, insulate with 4″ EPS, French drain, stone fill, copper termite flashing, then 4″ foam from sill plate up 4′ onto the house. Main reason for foam above silk was to make insulating rim joist easier than doing foam from inside. I’m replacing all the exterior doors. I have excavator coming next Friday, so I was pulling siding off up to 4′ aboveboard sill. When pulling a siding nail, the prybar went through the exterior wall. I thought, oh great, rotten osb. I now have siding pulled half way up all along the front of the house, and I only have OSB on the corners. The rest of the sheathing is 1/2″ polyiso. I am concerned with the vapor barrier that poly ISO would be. I didn’t even consider this would be on the house. Eventually 4″ of foam on whole house.
1. Should I leave the poly ISO or replace with plywood? Since I intend to use 4″ EPS foam.
2. If I keep polyiso can I airseal it at the seams like I was going to do to the osb I thought was there? Or will this cause an issue with dewpoint?
3. I already have tyvek drainwrap, I can still use this over the polyiso but under the EPS?
4. Will the case of 3m 8067 tape I have fix/repair any holes/breaks in the face layer I created?
5. Should I give up and just insulate the crawl from the inside?
My main concern is with dewpoint/moisture issues, cavity fiberglass behind poly ISO looks fine.
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