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Community and Q&A

AirTightness without Sprayfoam

homedesign | Posted in Energy Efficiency and Durability on

I am searching for Airtightness strategies that are achieving 1.5 ACH50 or better.
I am also trying to avoid sprayfoam for a variety of reasons.

If you are achieving good airtightness without spray foam please comment here

or join this discussion at the JLC Building Science Forum
Thank You,
John Brooks

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  1. GBA Editor
    Martin Holladay | | #1

    Here's a link to a GBA case study house that achieved 0.7 ACH@ 50 Pa — almost as tight as a Passivhaus — using cellulose insulation rather than spray foam.

    Almost all of the superinsulated houses of the late 1970s and 1980s — beginning with the landmark houses in Saskatoon and Regina (Saskatchewan) — achieved excellent airtightness results without spray foam. What it took was attention to detail, using gaskets, caulk, and (often) Tremco-sealed interior polyethylene "air/vapor barriers," as the detail was referred to then.

  2. Allison A. Bailes III | | #2

    I got to 1.7 ACH50 in a SIP house I built, and that was before I'd ever seen or done a Blower Door test. I think the biggest contributor to the leakage was the band joist, which I didn't do a great job with. If I were to do that house over again, I could easily get below 1.0 ACH50 by doing a better job with the band and installing tighter doors.

  3. NH Green Builder | | #3

    Use the Certainteed Optima Blown in Blanket (BIB) dense pack fiberglass system for walls and sloped ceilings. Consider a layer of rigid foam on the exterior. Use Huber Zip Wall system. Use sill sealer and caulk under all exterior wall plates and caulk/seal gaps in exterior wall framing (consider a blower door test before sealing up to find any weak spots). Use ridid foam blockers for rim (band) joists. You should be well under your target.

  4. will goodwin | | #4

    The CANADIAN HOMEBUILDERS ASSOCIATION BUILDERS MANUAL covers using poly, drywall and housewrap for an air barrier.

  5. GBA Editor
    Martin Holladay | | #5

    Thanks for the suggestion.

    For those who want to get the manual, here's a link for ordering information:

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