Exterior foam wall assembly without interior polyethylene
I am building a Net Zero home in Edmonton, Alberta Canada and plan on using 6″ of EPS or XPS rigid foam on the exterior of a traditional 2×6 wall sheathed with OSB and filled with Roxul batts resulting in about an R-40 wall.
The building code here calls for polyethylene on the interior and a maximum 1/3 rule for insulation on the exterior however the recommendation on this site is at least 4″ of exterior rigid foam and no poly for a wall like this(I assume my climate zone is 6). How can I convince the city to accept my design and how can I ensure air tightness without poly?
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