Architect Richard Pedranti, HERS rater Pete Vargo, consultant Bryan Kehm, and builder Rob Ciervo tape plastic over the OSB sheathing during a blower-door test.
Michelle Sangster Architect Richard Pedranti, HERS rater Pete Vargo, consultant Bryan Kehm, and builder Rob Ciervo tape plastic over the OSB sheathing during a blower-door test.

Building codes are getting tougher about airtightness. In the 2012 International Energy Efficiency Code (IEEC), blower-door testing is required for new homes, and the limits have gotten stricter. While the 2009 code specified 7 ACH50 (7 air changes per hour at 50 pascals of pressure), the 2012 code calls for 5 ACH50 for southern homes and 3 ACH50 for homes in the northern U.S.

Many builders will have to change their ways to meet the 2012 code’s requirements. But code-compliant airtightness is a piece of cake compared with the stringent specification for the voluntary Passive House standard. Passive House allows no more than 0.6 ACH50—five to eight times tighter than the 2012 code. These days, Passive House builders...

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