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Community and Q&A

Brick veneer and double stud walls?

Jonathan Rich | Posted in Energy Efficiency and Durability on

I am planning to build a home in southeastern Michigan (zone 5a), with a masonry veneer first floor and siding on the second floor.
I read the “Super Insulated House specs” blog, but I’m curious about the combination of double stud walls and the masonry veneer. Since this space can get wet due to penetration through the masonry, I would think this would eliminate a flash and batt/fill insulation technique, as the sheathing would only be able to dry to the outside. If rigid foam is to be applied external to structural sheathing, does this result in an inch for inch increase in the size of the foundation brick ledge? What would be the strategy to drain/ventilate the space between the masonry and the constructed wall? Should there be provisions to ventilate this space where the masonry and siding meet, or should the gap between the masonry and foam be made contiguous with rain-wall gap behind the siding. I think this approach would result in an offset, or building out the thickness of the wall for the second floor to keep the siding at about the same plane as the exterior of the masonry. Does anyone have an example wall section for a high R-value wall behind masonry?
Thanks,

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Jonathan,
    You ask a lot of questions; I'll try to bite off a few of them.

    The space behind brick veneer should always be ventilated. Open slots at the bottom of the wall act as weep holes and air inlets, and the top of the wall should be vented to the exterior or the soffit.

    The best type of wall sheathing behind brick veneer is foam sheathing. I think it probably makes more sense to install adequate foam thickness for your climate over 2x6 framing rather than building a double wall, in part because you really want the foam anyway.

  2. Brett Moyer | | #2

    Martin,

    Why is foam the best sheathing behind brick? We aren't talking about a hot humid climate here. Though I'm not completely familiar with the climate in southeastern Michigan, I doubt the walls are are going to experience much solar vapor drive. I could be wrong.

    Wouldn't the main concern be the drainage plane behind the brick veneer, not the sheathing type?

  3. John Brooks | | #3

    I question the strong preference for foam sheathing as well.

    As I listen to this podcast ... it seems to me that you can have a succesful assembly without foam sheathing.
    https://www.greenbuildingadvisor.com/blogs/dept/building-science/rain-control-energy-efficient-buildings-building-science-podcast#post_comments

    like Brett says...I could be wrong

  4. GBA Editor
    Martin Holladay | | #4

    Brett,
    Q. "Why is foam the best sheathing behind brick?"

    A. Inward solar vapor drive -- yes, even in Michigan. However, I agree that plywood can work fine. But brick veneer can hold a lot of water, and has been associated with many inward solar vapor drive problems.

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