home air leaks & home air sealing basics
Home's air leaks can be a source of discomfort, moisture, unhealthy air and high energy bills. But most air leaks aren't necessarily the most noticeable.
People are more aware of small openings and cracks around doors and windows, fireplaces or chimneys, than of infiltration and energy losses associated to the attic, crawlspaces and basements, or ducts and plumbing... But these are, in many cases, the major sources of air leakage.
Stopping air leaks in windows and doors (or around them) by caulking and weather-stripping them is important but often insufficient.
The image, from DOE, shows the average importance of the most typical home's air leaks.
See:
Window and Door Air Sealing
Dropped Ceilings Sealing
Caulking Electric
Attic Air Leaks and Sealing
Air Sealing Bathtub Plumbing
Sill Plate and Rim Joist Air Sealing
Chimney and Fireplace Caulking
Sealing Exterior Walls
Finding Home Air Leaks
Image: Dow Chemical
Home Air Sealing Materials
There are several types of air sealing materials, responding to different needs:
1- Caulks - silicone, urethane, latex....- for small gaps and holes;
2 -Air sealing foams (polyurethane based, but not only) for medium openings, say, between 1/4 inch /5 mm and 3 inches/60 mm wide);
3 - Air barriers for larger openings and to air seal large surfaces in wood and steel frame homes;
4 - Several types of weatherstripping materials to air seal movable parts in doors and windows...
The quality and the properties of these different types of air sealing materials also vary a lot, making the choice more difficult...
See also:
Foam Sealants;
Sealing Products;
Caulking Products
Caulking Tips
Caulk and Sealant Manufacturers
The best of caulking and air sealing
Insulation vs. Home Air Sealing
Insulation doesn't provide air sealing (a very common proof is on well insulated attics with dirty insulation: a telltale sign that the insulation layer is behaving like a filter, and isn't preventing air leakage).
There are very few materials able to fulfill both functions, though some polyurethane foams may provide both sealing and insulation...
See: Insulation vs. Air sealing materials
Tests & Home air leaks
You can carry out yourself some easy tests to identify air leakage sources in your home. But you may need or want a professional energy audit, involving insulation and air leakage.
See: Home Audit Basics
Air tight Homes
Do not rely on air leakage for home ventilation. You will get too much cold air during bad weather conditions or too less in hot and non-windy conditions.
More important, in cold climates bet on an airtight home and on a mechanical ventilation system. That's the best way to get energy savings and a much smaller heating and cooling system.
See: Airtight Homes
Structural Air Sealing
Most air leakage problems can be avoided by doing it rightly the first time. Many structural home's air leaks are due to construction flaws.
If building a wood or steel frame home, pay attention to air and vapor barriers. The home's shell (floor and foundations, walls and ceiling) should benefit from a continuous air barrier...