About Blower Door Testing


DMT Foam focuses on the building envelope (outer walls, floor, ceiling or roof) as part of the energy efficiency equation. Our goal is to create an exact balance of how a heating/cooling system conditions the air and how the house uses (or wastes) the conditioned air.

We use blower door testing to measure a building or home's "airtightness" and to locate air leakage sites. The blower door test is a proven, objective means to identify air leaks in a home. It removes the guesswork of weatherizing and improving a building’s efficiency and comfort.


Our Blower Door Testing Process


To conduct the blower door test, DMT Foam technicians close all openings within the house. We then attach a special, calibrated fan within the frame of an exterior-door. The fan pulls air from the house and gauges measure the air flow through the fan. Other gauges measure the difference between indoor and outdoor air pressures. To calculate the leakage rate, we adjust the fan to maintain a constant pressure differential.

The number of air changes per hour (the complete replacement of the indoor air volume in an hour) at a standard pressure differential (pressure inside the house minus pressure outside the house, measured in Pascals) tells us how the house is performing. Five air changes per hour at 50 Pascals differential pressure (5 ACH50) is a reasonable performance standard.

During the test, outdoor pressure forces air through openings in the building envelope. Often, it is easy to feel these leaks with bare hands. Other times, we use a smoke pencil or infrared light to detect where cooler air is seeping into the house.

Once the leaks are found, we will help you determine the best and most cost-effective insulation solution for your project.