Air leakage occurs when uncontrolled or outside air enters and conditioned air leaves your house through cracks and openings. 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 your home’s durability, increase comfort by reducing drafts and cold spots, and create a healthier indoor environment. In addition, the potential energy savings from finding and repairing these leaks in a home can be valuable.
Detecting Air Leaks
You can start with a careful visual inspection inside and out. Look for gaps and cracks at the common points of air leakage (i.e., knee wall doors, dryer vents, attic hatches, electrical outlets, cable TV and phone lines, sill plates) and pay close attention to the windows, doors, and other openings of your home. A home’s biggest air leaks are usually located in large areas, such as the attic or basement. But small leaks do exist and can become a big problem, too. Check for gaps along baseboards, edges of flooring, and junctures of walls and ceilings. Also check in areas where two different building materials meet (i.e., all exterior corners, where siding and chimneys meet, and areas where the foundation and the bottom of exterior brick or siding meet).
Repairing Air Leaks
Caulking and weatherstripping are two simple and effective do-it-yourself air-sealing techniques that offer quick returns on investment. Caulk is a flexible material generally used to seal air leaks through cracks, gaps, or joints less than one-quarter-inch wide between stationary building components such as around door and window frames. Weatherstripping is generally used to seal components that move, such as doors and operable windows. Before caulking air leaks or applying weatherstripping in an existing home, you will need to assess your ventilation needs to ensure adequate indoor air quality.
Ventilation refers to the exchange of indoor and outdoor air. Without proper ventilation, an otherwise insulated and airtight house will seal in harmful pollutants, such as carbon monoxide, and moisture that can damage a house.
In homes that use combustion appliances— appliances like stoves and fireplaces that burn natural gas, oil, propane, kerosene, or wood — you must always be aware of the danger of indoor air pollution and be certain the appliance has an adequate air supply when sealing a home. Otherwise, gases can accumulate in a poorly ventilated home and threaten your health and safety.
Generally, one square inch of vent opening is required for each 1,000 Btu of appliance input heat. Burn marks or soot around the appliance burner or at the vent collar, or visible smoke anywhere while the appliance is operating, indicate poor ventilation.