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Double stud wall with batt insulation in Toronto

lowelllodesign | Posted in Green Building Techniques on

Mr. Martin Holladay,

I am an Architect in Toronto. I may be involved in a small interior alterations in which part of the exterior wall needs to be reinsulated. The existing construction of the wall is aluminum side, wood sheathing and 2″x4″ studs with no insulation. To bring this wall up to code I need R-24. The contractor is looking to build cheap so he wants to build a second stud wall to create double stud wall and insulate with batts only and vapour barrier. My question is will the exterior sheathing gets cold with so much insulation? Is there a chance of condensation?



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  1. GBA Editor
    Martin Holladay | | #1

    Most aluminum siding hangs loosely, so this wall can probably dry to the exterior.

    I know that Canadians like interior vapor barriers, but in Toronto, you really only need an interior vapor retarder, not a vapor barrier -- especially if this house might ever be air conditioned. A smart retarder like MemBrain makes more sense than interior polyethylene.

    For more information on moisture accumulation in sheathing, see How Risky Is Cold OSB Wall Sheathing?

  2. lowelllodesign | | #2

    Thanks again Martin!

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