Air Sealing and Ventilation

Air Sealing a Cold, Drafty House

Air sealing is often one of the most cost-effective measures you can take to make your home more energy efficient and comfortable. Unless your house was built in the last 5 to 10 years, there are probably major air leaks in the living space and in the building shell. Older homes can be extremely leaky, which means the hot or cold air that your heater or air conditioner puts out is mostly blowing out of the house!

Air sealing needs to be evaluated and done by a professional because a home does need some ventilation so that the air isn't too stagnant. If an older home is sealed too tightly, a mechanical ventilation system — sometimes called an Energy Recovery Ventilator — may need to be added to ensure healthy air quality.

The right first step is to get an in-home energy audit to determine how much air leakage your home currently has and how much of that leakage can be safely sealed to maximize your utility bill savings and minimize your carbon footprint.

Testing to Reveal Air Leaks

A blower door test is one of the most common tools energy auditors use to figure out where air is leaking in and out of your home. The point of a blower door test is to depressurize your home by inserting a door with a built in fan that will blow air out your entryway. As the air inside your home is pushed outside through the front door, air from outside of your home will start to seep in through the cracks.

Auditors then use colored smoke to make the moving air visible. They will note the areas where air is seeping in during the blower door test so they can come back and seal them up later using foam, caulk or other sealants.

The most common problem areas blower door tests point out are found on exterior walls or walls that connect to garages, as well as ceilings and floors connecting to attics and crawlspaces. The windows, chimneys, vents, recess lights, attic hatches, electrical outlets and outdoor faucets found on these exterior walls are often high-leakage areas that can be easily sealed.

It's also important to note that air sealing and insulation go hand in hand. If you plan to add insulation to improve the efficiency of your house, be sure to talk with a professional about air sealing at the same time. Without air sealing, your new insulation may be much less effective.

Last Updated: April 2010

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