Making your home more airtight will make it less expensive to heat and cool, while also improving interior comfort. Air sealing is the process of sealing leaks in a home's building envelope to limit the amount of air that leaks out of and into the house. Conditioned (heated or cooled) interior air leaking out of the house is called exfiltration. Outside air that leaks in is called infiltration. Most air exfiltration takes place through the attic. The basement or crawl space is a major source of air infiltration.
Air leaks cost you money. It's like leaving a window open. Add up the area of all the gaps, cracks and openings where energy can escape in a typical house and you'll easily equal the area of an open window. Gaps can be small, like those around an electrical outlet in an exterior wall. They can be large, like the holes that plumbers often drill in floors and framing to install pipes. And they can be long, like the gap on the outside of the house where the eave soffit is supposed to meet the exterior wall.
Air sealing saves you money. Sealing leaks in a home's building envelope, a process called air-sealing, increases comfort and energy efficiency while decreasing your fuel bills. Air-sealing can be simply described: Find leaks, then sealing them. But this is easier said than done. Finding air leakage demands specialized equipment (such as a blower door), skilled detective work and the ability to access parts of the house most homeowners can't easily reach or don't want to. Once leaks are properly identified, it's important to select the right specialty products and use professional techniques to seal them.
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
- Cracks, gaps & holes in drywall or plaster
- Electrical outlets and switches, especially on exterior walls
- Gaps around window and door trim and baseboard moldings
- Dropped ceilings & soffits
- Leaky basement windows
- Rim joists in the basement or crawl space