Reducing the amount of air that leaks in and out of your home is a cost-effective way to cut heating and cooling costs, improve durability, increase comfort, and create a healthier indoor environment. Caulking and weatherstripping are two simple and effective air-sealing techniques that offer quick returns on investment, often one year or less. Caulk is generally used for cracks and openings between stationary house components such as around door and window frames, and weatherstripping is used to seal components that move, such as doors and operable windows.
Air leakage occurs when outside air enters and conditioned air leaves your house uncontrollably through cracks and openings. It is unwise to rely on air leakage for ventilation. During cold or windy weather, too much air may enter the house. When it's warmer and less windy, not enough air may enter, which can result in poor indoor air quality. Air leakage also contributes to moisture problems that can affect occupants’ health and the structure’s durability. An added benefit is that sealing cracks and openings reduces drafts and cold spots, improving comfort.
The recommended strategy is to reduce air leakage as much as possible and to provide controlled ventilation as needed. Before air sealing, you should first:
For a thorough and accurate measurement of air leakage in your home, hire a qualified technician to conduct an energy assessment, particularly a blower door test. A blower door test, which depressurizes a home, can reveal the location of many leaks. A complete energy assessment will also help determine areas in your home that need more insulation.
Without a blower door test, there are ways to find some air leaks yourself.
On the outside of your house, inspect all areas where two different building materials meet, including:
Inside your home, inspect around the following areas for any cracks and gaps that could cause air leaks:
You can then apply air sealing techniques and materials, including caulk and weatherstripping. If you're planning an extensive remodel of your home that will include some construction, review some of the techniques used for air sealing in new home construction and consider a home energy audit to identify all the ways your home wastes energy and money.
Note that air sealing alone doesn’t eliminate the need for proper insulation to reduce heat flow through the building envelope.
U.S. Department of Energy