That funny ribbed foam between the wood and the poured...

That funny ribbed foam between the wood and the poured concrete foundation is a gasket that prevents air leakage into a home. (2012) Credit: Tim Carter


You can fix many air leaks in the home, even on the coldest days of the year. You may be a little uncomfortable as you work, but you can have lots of success:

1. The first place to look: doors and windows. These two places can account for a significant amount of air leakage. Be sure the weatherstripping is in good shape and in contact with the doors and windows. If you have wood trim around doors and windows, air could be entering there. It's not uncommon for builders and remodelers to do a poor job of installing insulation between doors or windows and the rough openings. It may pay to remove the wood trim carefully to see if the narrow cavity is insulated.

2. If it's not, you can insulate around windows and doors with expanding foam. If you use this product, be sure you use one that is made for doors and windows. If you use the wrong one, the foam can expand too much and cause the window or door not to open and close properly. You can also carefully stuff strands of fiberglass insulation around windows and doors. Do not pack it too tightly.

3. Electrical outlets on exterior walls can be sources of air leaks. In the winter, you can stop some of the air with the following fix: Remove the cover plate. Take a wet-dry vacuum and carefully clean any dust from sides of the box and the plaster and drywall around the box. Usually there is a gap between the box and the wallcovering material. Caulk this gap. Then, put the plate back on.

4. Air leaks can happen through electrical service boxes, but these can't be sealed easily after a house is built. The entry hole where the electric cable enters the box can be sealed before the house is insulated and the drywall is up, but to do it afterward is highly problematic.

5. If you have access to your attic, go there with a good flashlight. If you have fiberglass insulation up there already, it can tell you where air leaks are. When you see black or dirty insulation, it's acting like an air filter in your furnace. Air is passing through the insulation, and the fiberglass is capturing the dirt. Trace the source of the air leak and seal it.

6. Be sure to turn off any lights in the attic and look for light leaks through the insulation. These light leaks are almost always air leak locations. Be careful around recessed lighting. Older recessed lights must not come into direct contact with insulation. You have to construct a special housing that creates an air space around the entire fixture before you insulate around it. Check with your fire prevention officer if in doubt about how to do this.

7. The building code in most places requires an air gap between chimneys and any wood framing. Check with your town. This gap can be a huge source of air leakage. You can stuff this gap in the attic with fiberglass batts to stop air from pouring down into your home.

8. Inspect your basement for air leaks where the wood framing is in contact with the foundation. Air leaks here can be sealed with caulk from the interior during winter months.

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