Vapor retarder on interior if exterior has vapor barrier?

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Vapor retarder on interior if exterior has vapor barrier?

This question stems from a different conversation on here and we need some more help.

We're in Zone 5A. Our exterior has plywood, tar paper, 1" of foil-faced polyiso foam, and red cedar shake. The framing is 2x6 wood construction.

The interior will be heated with wood stoves only. We know to never have 2 vapor barriers. What we're wondering is if we need an additional vapor retarder on the interior? If so, what sort of barrier do we need? (Spray foam is prohibitively expensive).

We were planning on having R-21 cellulose insulation and then 1/2" gypsum on the interior. Would too much moisture get in in the winter?

Asked by Cathy O
Posted Mon, 12/03/2012 - 22:54
Edited Tue, 12/04/2012 - 09:12

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