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Wall construction Zone 3A w/h

je7W5JsovA | Posted in General Questions on

I am building a new home and would like to verify the correct placement of material. From the inside to outside: sheetrock > 2×6 > dense pack cellulose > OSB > foil faced polyiso foam > brick.
Covered back patio is same except hardie type siding instead of brick and polyiso with no foil face.

Would house wrap be redundant if placed over the OSB? Or is the polyiso foam overkill for this zone (which I think would then necessitate the house wrap)?

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  1. GBA Editor
    Martin Holladay | | #1

    A few comments:

    1. Polyiso behind brick is an excellent idea. It improves the thermal performance of your wall, and also stops inward solar vapor drive -- a problem with brick veneer walls.

    2. You didn't mention the air space between the polyiso and the brick. It's important.

    3. Every wall needs a water-resisitive barrier (WRB). You can use the polyiso as the WRB if you want, but doing so is tricky. Most builders prefer to use housewrap as a WRB. For more information on WRBs, see:

    All About Water-Resistive Barriers

    Using Rigid Foam As a Water-Resistive Barrier

  2. je7W5JsovA | | #2

    Thanks. Easy enough to put a WRB on top of sheathing then.
    The air space is about 1" between brick and foam.

    Been getting some resistance about dense pack cellulose, but not sure why, except guys here aren't using it and 'you really need to use foam'.

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