Air Sealing

Air sealing is the process of sealing leaks in a home's building envelope to limit the amount of conditioned air that leaks out of the house and the amount of unconditioned outside air that leaks in.

During a home energy audit (aka home energy assessment), air leakage is measured during a blower door test.

This test not only determines how much air leakage is occurring; it also enables technicians to pinpoint leak locations.

What's so important about air sealing?

Not air sealing a home is like
leaving a window open.

Many houses have two or three times the amount of air leakage that building scientists recommend for optimum energy efficiency and indoor air quality. With excessive air leakage, you're always losing air that you just paid to heat, cool or dehumidify, and replacing it with outside air that needs to be heated, cooled or dehumidified.

The warmest air in the house rises naturally by convection the same process that causes a hot air balloon to rise. As this warm air escapes into the attic and out of the house, a matching volume of outside air gets sucked into the house through leaks in lower areas especially basements and crawl spaces. This combination of air exfiltration and air infiltration is called the Stack Effect a major factor in energy loss and high utility bills.

Air sealing can reduce heating & cooling costs by 20% or more

Sealing air leaks to make your house more airtight will make your living space more comfortable and more affordable to heat and cool. Air sealing is essential for certain types of insulation to perform effectively, so it's usually combined with insulation upgrades.

Air sealing targets common air leakage locations

Here are some of the locations where air leakage occurs in a typical house:

• Plumbing and wiring penetrations through floors, walls and ceilings
• Chimney penetrations through insulated ceilings and exterior walls
• Attic access hatches, doors and drop-down stairs
• Recessed lights and fans in insulated ceilings
• Weatherstripping around windows and exterior doors
• Holes in drywall or plaster
• Electrical outlets and switches, especially on exterior walls
• Trim around windows and doors; baseboard moldings
• Dropped ceilings above bathtubs and cabinets
• Hollow cores in concrete block walls

Back to previous page