Vapor Retarders/Double Air Barriers
May I ask to ensure we haven’t missed anything in thoughts on building our home. I was under the impression we would use Closed Cell Spray foam for the entire assembly, but my husband is now thinking Open Cell for the above grade walls. Will these assemblies work?
Unvented Cathedral Ceiling
Metal Roof/Air Gap/Asphalt Felt/ZIP Roof Sheathing/Closed Cell (still negotiating the amount)/Back Venting/USG Ultra Light Drywall
Vented Unconditioned Ceiling
Metal Roof/Air Gap/Asphalt Felt/ZIP Roof Sheathing/Air Gap/Fiberglass Insulation with Kraft Paper (Kraft needs to be on which side, I get confused where everyone states “warm in winter” side)/DensArmor Drywall
Brick Veneer/Rain Screen Gap/ZIP Sheathing/Open Cell Spray Foam/(Vapor Retarder needed?)/DensArmor Drywall
I worry about the Open Cell Spray Foam and the need for a Vapor Retarder in Climate Zone 5. I will not put plastic in the walls, that caused damage in our last home. I am reading up on the Primer that can be applied to the drywall to act as a vapor retarder, so that might be an option.
GBA Detail Library
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