Blower Door Testing: Is My House Leaky or Tight?

When you hear of leaks in your home, you probably think of those involving water and plumbing, but what about air leaks? Homes that experience excessive air leakage are difficult to heat and cool. Too much air flowing in and out of your house can cause several problems such as wasted energy and high cooling and heating costs, moisture condensation, uncomfortable drafts from the outdoors and poor air quality flowing throughout your home. In fact, air leakage can account for up to 30 percent of your cooling and heating costs. The only way to know whether your home is leaky or tight is to measure its air leakage rate with a blower door test conducted by a trained professional. This test provides a highly accurate and cost-effective method for determining your home’s air leakage performance.

A blower door is a powerful fan that mounts into the frame of an exterior door. The “door” comes with a built-in fan and multiple gauges that measure air pressure. The fan removes air from your house, lowering the pressure inside. In turn, higher-pressure outdoor air will work its way through cracks and unsealed openings, making the leaks easier to measure and locate.

Before a blower door test can be performed, the following preparation is required:


  • Close all exterior doors and windows
  • Open all interior doors
  • Remove any ashes from open fireplaces or cover the ashes with damp newspapers
  • Walk-through your home with the auditor to point out areas that you know are drafty or difficult to condition comfortably
  • Close any fireplace dampers, doors and woodstove air inlets
  • Turn off the clothes dryer and all bathroom and kitchen exhaust fans

Once the blower door is set up and operating, many leaks can be found by feeling around with your bare hands or with the use of an infrared camera. The infrared camera finds air leaks through temperature differences. To use the camera alone, the temperature outside and temperature inside have to be very different, but since it’s difficult to plan an audit around the temperature outside, it is best to use the blower door and camera together. By creating a pressure difference that allows the air to move, it is not necessary for there to be a large temperature difference to be able to see the air movement through the cracks and holes allowing for a much better chance to find all the problem areas. View our video about this process.

After the blower door test is completed and the air leakage rate for your home is determined and evaluated, the auditor will assist you in identifying improvements that will potentially save the most on your energy costs and recommendations to improve comfort and indoor air quality can then be made.

When you have a home energy audit conducted by CAEC’s Energy Services Representative, a Certified Residential Energy Auditor, you can choose which level works best for you and your budget. The initial cost of either audit is reimbursed when ESR-recommended improvements are made to the home within a 12-month period of time. The Basic Audit cost is $75 and the Advanced Audit (includes blower door test) cost is $100. For more information, see our energy audit page for more details or call (800) 545-5735 ext. 2178 or (334) 351-2178.