If your new home has ductwork running through unconditioned spaces—like an attic, uninsulated basement, or crawlspace—it’s essential to test the ductwork for air tightness. This test is required by Pennsylvania residential building code and ensures your home is as energy-efficient as possible. To perform the test, we use a duct blaster, a small but powerful fan attached to the air handler or a central return grill. The fan pressurizes the ductwork, and we measure air leakage using pressure gauges to identify any weak spots.

The 2018 building code in Pennsylvania sets a high standard for ductwork tightness, requiring that it meet 4 CFM (cubic feet per minute) of leakage per 100 square feet of conditioned space with the fan running at standard pressure. This test is required only if any portion of the duct work runs through unconditioned areas such as attics and garages. Achieving this level of airtightness requires both a well-sealed air handler and well-sealed ductwork.

For homes that are permitted under the 2021 building code, there are some changes – all air handling duct work must be tested anywhere in the house.  If any portion of the ductwork Is outside of the thermal barrier, as in an attic, the requirements are still 4 CFM of leakage per 100 square feet.  If all of the ductwork is within the thermal envelope, as in a heated basement, then the requirement is 8 CFM per 100 square feet.