We are building a 700-sq.-ft. cottage on southern Vancouver Island, Zone 4 Marine
The plan is to use 4 inches polyisocyanurate – R22.6 – (glass fiber covering) exterior insulation no sheathing except for earthquake walls. No insulation in the 2×4 wall cavities, tyvek on the exterior of the foam and vapor barrier between the polyiso and the framing. ls this ok or will we have problems. We have to present our wall assembly plans to the city and the city wants a vapor barrier but we are not sure if this is necessary.
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