This post originally appeared on the Green Building Advisor Website.
A couple years ago I was asked to perform a blower door test on a new home. The home was small with a footprint of only 1130 square feet. When the test was completed, the test report indicated an air leakage rate of 91 CFM at the test pressure of 50 Pascals, .33 ACH50. Completely unexpected for this code-built house. (I actually measured the volume of the home again and ran the test two more times before I was convinced I had an accurate test.) The contractor contacted me some time later and indicated the homeowners were noticing air coming through the exterior light switches when the dryer was operating. The dryer was producing close to the same negative pressure as my blower door every time it was being used, a negative pressure of about 50 Pascals. Is this a problem?