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Community and Q&A

External wall details

Ray Smith | Posted in GBA Pro Help on

I have been in Canada, BC, for three years now having previously been a main contractor building very energy efficient homes in Europe based towards the PassivHaus standards. I am currently a certified energy advisor and have been asked by a client to help him out with his new house build. As the construction methods are different here I’d just like a little advice, or back up, for the following detail.
From the inside, drywall, Certain Teed Membrain, 2×6 studs filled with either cellulose or R22 Roxul, 1/2″ ply, 2″ styrofoam board, house wrap fully taped up as an air barrier. The client has told me that he wants to use stucco to the exterior and is concerned about the fixing of this. I am proposing to use 1×3 or 1×4 strapping battens over the styrofoam and then add another sheet of ply as backing for his stucco. This should keep the air barrier intact?
Many thanks.

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  1. GBA Editor
    Martin Holladay | | #1

    It isn't necessary to install two layers of plywood.

    On top of the foam, you can either install vertical strapping, followed by a WRB and welded-wire lath, or you can install one of the new products that integrate a three-dimensional drainage space and a WRB. Stucco installers in British Columbia should be familiar with these techniques.

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