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Air barrier details and water management details in Arizona: a video

Martin Holladay | Posted in Energy Efficiency and Durability on

We didn’t produce this video — it was actually produced by Builder magazine — but it features two people known to GBA readers, Dan Morrison and Peter Yost.

Dan and Peter visit a construction site in Arizona, and inspect air barrier details and water management details.

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Replies

  1. John Brooks | | #1

    Hi Martin,
    how well did these homes "Test" on a blower door?

  2. GBA Editor
    Martin Holladay | | #2

    John,
    I don't know. On one of the company's web pages, Meritage Homes brags that "The Home Energy Rating is completed from on-site visits using test equipment like the blower door and duct tester, and from blueprints on new homes" -- but I don't see an actual report of the results.

    In 2011, Meritage Homes won an award (and EnergyValue Housing Award) for a brick veneer home in Gilbert, Arizona. That home had an air leakage rate of 2.0 ach50. For more information on that home, see 2011 EnergyValue Housing Award Report, pages 32 and 33.

  3. John Brooks | | #3

    Martin,
    The EVHA House you linked to with the 2.0-ACH50 score seems to have a different type wall with staggered double stud walls.

    I guess I was expecting to see some air barrier details in the video....
    Perhaps.. details that showed how the different Air Barrier materials "connected" to one another.

    One reason that I'm curious how the House "tested"....
    It's obvious that the house has spray foam in the wall cavities and between roof rafters.
    But ...
    It doesn't look like they attempted any "Caulk & Seal" between framing members?
    Maybe they were going to come back and caulk & seal later?

    I am also curious how the stucco "connects" to the other air barrier materials to "complete the exterior air barrier transition from the wall to the conditioned attic" ???

  4. Expert Member
    Dana Dorsett | | #4

    They also didn't exactly fill those stud bays with the open cell foam either, eh? Did the foam even hit that square inch of sheathing (or sheathing foam?) in the upper left bay with the missing seam caulk? I'd bet it sticks out like hot coal on an infra-red imaging scan.

    Stucco applied directly to the EPS on the exterior makes it sorta-reasonably air tight though (at least temporarily) even without the detailing the framing seams. There's tight/tighter/tightest, but no such thing as perfection in the air sealing biz.

    Homes in AZ are often built without structural sheathing, only shear-panels (like the one in the video) or cut-in-bracing, with an inch of foam on the outside onto which stucco gets applied. In these homes it's easier & quieter for thieves to kick-in or cut holes in the walls than it is to break a window or door to gain entry (and it happens.) As the stucco ages and inevitably cracks the less-robustly braced walls, the air tightness is compromised, even if it's blowing less than 3ACH/50 on the day the builders walked away. The o.c. foam on this home makes it somewhat more robust on long term air tightness than those using the more common R13 batts, but this type of construction doesn't strike me as very high performance or sustainable, given how non-robust the basic structural aspects are.

    What's the upcharge for skinning it fully in OSB or ply? Too much, por que:

    Unstated is the local market conditions in that region of the US that drives home builders to cut ever more corners, including (but not limited to) undocumented foreign labor (usually Mexican or central American), who are too often bilked of even the substandard wage promised by even less-scrupulous builders, who can then charge even less for a home. Anybody paying union-scale and building to a decent standard on performance & structural capacity has a tough time competing when competing price expectations are set so low. It has to be a tough place for a home builder with higher standards to do business, so I suppose the fact that they give air sealing any thought at all gets to be considered "high performance", relative to the competition. But I can't imagine building a house that I intended to live in for decades that way.

    This is in no way a knock on Meritage Homes (the practices of whom I am agnostic), only to point out how tough it is to compete on price/performance in AZ compared to some other US markets.

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