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Poly Iso insulation question


white collar hillbilly
May 28, 2020
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pole barn....

Picked up some reclaimed Poly-iso insulation with the "fiberglass"/fabric coating. Plan is to use to insulate the walls of the pole barn. Barn is already wrapped with the foil insulation. Wood (oak, in my case... milled at home) will be the finish surface over the poly-iso.
Question... do I need a plastic vapor barrier? Google-fu is providing mixed opinions...

Pic of POC... Yes - all wiring will be adjusted appropriately.

Click image for larger version Name:	20201101_204709966_iOS (2).jpg Views:	0 Size:	301.8 KB ID:	192095
What's on the other side of the foil? If you create a moisture trap in the wall the iso will get nasty in a hurry. At the same time I've been on plenty of roofs that had a full watertight seal under the insulation and a roof on top and nobody ever questioned it

Steel siding.

was kind of hoping that leaving the 1.5” air pocket would reduce risk of trapping moisture.

it does get very humid here and the may add wood heat in the future...
I'd let it breathe then. The iso does fine with normal humidity, you can store it outside tarped all summer and it's pretty much the same as when it's fresh from the factory
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