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Update on Blower Door Testing

I had previously written about Blower Door Testing to measure how well a completed home is air sealed. It is now a requirement in some of the communities that we build new homes in as a condition to receiving a certificate of occupancy. We recently performed a blower door test on a new house that we are building as soon as the house was tight to weather before the insulation was installed to help us determine how we could better air seal the building shell while it is still accessible.

This home includes the popular “ZIP” wall and roof sheathing and has all seams properly taped. It also has a 1″ DOW Tuff -R polyiso foam board applied to the outside of the sheathing with all seams taped. The windows and door perimeters were foam sealed, but no other wall sealing efforts had been completed prior to the testing.

Our test results were 1.89 ACH at 50 Pascals. Not too bad, but we have a pretty strict final target established of 1.0 ACH/50 that we would like to achieve. The test results have determined the need to air seal 38 square inches of leakage to achieve our target goals.

As the test was being conducted, we utilized an inferred camera to identify temperature changes in the building shell caused by air movement. When we found these areas, we used a smoke generating device to check if air movement was causing the differential. If so, we made a paint mark to identify the need to air seal that area.

We will conduct another blower door test after completing the air sealing and insulation installation to see how we did. So far, we have sealed all identified areas as indicated by our test. We went ahead and sealed the inside sheathing seams, top and bottom plates, gable rafters, and around window and door headers and studs, which had not indicated leakage but are areas that we would typically seal anyway. I will follow up with the results of the next blower door test after it has been completed.