I recently had the opportunity to attend a BS and Beer meeting in Kansas City, MO where the meeting took place in a home under construction. The home was being built by Aarow Building (Jake Bruton) of Columbia, MO (they recently opened an office in Kansas City). The home is a single level, slab on grade with around 3,250 square feet. At the time of the meeting, the home was just finishing the mechanical, electrical, and plumbing systems and about to move to the insulation phase. A perfect time for a mid-build blower door test.
The purpose of a mid-build blower door test is to confirm that the home is on track to meet the air tightness metric (Jake informed me that all his new homes are contractual bound to achieve 1 ACH50 or less) and to find any missed opportunities in the air sealing of the home. The mid-build testing can be simple, get the home to negative or positive 50 Pascals of pressure and record the CFM rate, this type of testing is called “single point”. If you feel the CFM rate (or the calculated air changes per hour at 50 Pascals number) is too high, set the fan on “cruise control” and go find the air leak locations. There’s no need to perform multi-point testing this early in the build, (a type of blower door testing where CFM rates are measured at progressively lower pressure points, usually starting at 60 Pascals), save that type of testing for the final blower door test. Continue reading “An Airtight Home, What Do the Blower Door Numbers Mean?”