Replies

1. GBA Editor
   Martin Holladay | Sep 09, 2009 12:02pm | #1

   John,
   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.
   https://www.greenbuildingadvisor.com/homes/passive-house-methods-help-build-future

   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 | Sep 09, 2009 03:06pm | #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 | Sep 09, 2009 08:46pm | #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 | Sep 15, 2009 06:38am | #4

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

5. GBA Editor
   Martin Holladay | Sep 15, 2009 07:16am | #5

   Will,
   Thanks for the suggestion.

   For those who want to get the manual, here's a link for ordering information:
   http://www.buildermanual.com/