Locating Air Leaks 4 - Plug the Big Holes Locating Air Leaks 4 - Plug the Big Holes

Don't worry about finding and sealing all the little holes in your attic, since your biggest savings will come from plugging the large ones. Once in the attic, refer to your sketch to locate the areas where leakage is greatest (where your walls, interior and exterior, meet the attic floor, the soffits and other dropped-ceiling areas, and behind attic kneewalls). Look for dirty insulation - this indicates that air is moving through it. Soffits may be filled with insulation or covered with cardboard or fiberglass batts. Push back the insulation and scoop it out of the soffits. The insulation will go back over the soffit once the stud cavities have been plugged and the soffits covered.

1. Create Stuffed Bags

Fold the bag and stuff it into the open stud cavity. Add more insulation to the bag if it doesn't fit tightly. Plug all open studs spaces. Then cover soffit.

2. Plug Open Stud Cavaties

Cut a 16 in. long piece from a batt of unfaced fiberglass insulation and fold it at the bottom of a 13-gallon plastic garbage bag.

3. Cover Soffits & Chaseways

Cut a length of reflective foil or other blocking material about 6 in. longer than the opening to be covered. Apply a bead of caulk around the opening. Embed the foil in the cualk and staple or nail it in place if needed. Then cover the area with insulation.

4. Sealed Behind Kneewalls

Cut a 24 in. long piece of from a batt of fiberglass insulation and place it at teh botton of a 13-gallon plastic garbage bag. Fold the bag over and stuff it into the open joist space under the wall. Again, cover with insulation when you're done.


If You Have a Finished Attic, Seal Behind the Kneewalls

Finished rooms built into attics often have open cavities in the floor framing under the side-walls or kneewalls. Even though insulation may be piled against or stuffed into these spaces, they can still leak air. Again look for signs of dirty insulation to indicate air is moving through. You need to plug these cavities in order to stop air from traveling under the floor of the finished space. (See photo 4.)

Caution: Some attics have vermiculite insulation, which may contain asbestos, a health hazard. Vermiculite is a lightweight, pea-size, flaky gray mineral. Don't disturb vermiculite insulation unless you've had it tested by an approved lab to be sure it doesn't contain asbestos. Contact your local health department for the name of an approved lab.

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