Attics, Knee Walls, Eaves
Leaks at key places where framing comes together—attics, knee walls, cantilevers, and eaves—can account for a home’s biggest heat losses. These hard-to-reach spots may not have enough insulation, or what’s there might be installed incorrectly. Not surprisingly, Torrey's infrared camera showed missing or underperforming insulation in all these places.

Again, Tom will come back and remove the dirt-coated fiberglass Torrey found so he can insulate the eaves and the knee walls with expanding foam. Since Maddy and Paul will place their new, efficient HVAC equipment in the attic, Tom will also coat the underside of the roof sheathing. Torrey notes that for attics that don't double as mechanicals rooms, it's better to seal the flat attic floor; blown-in cellulose provides great results for this application, he says. For homeowners who can't afford all-new insulation, Torrey recommends a hybrid approach for gaps in these framing details. "Sometimes it's a long crack, sometimes large chaseways," he says. A combination of expanding foam, rigid boards, and blown-in cellulose can assure that an air barrier and insulation work as one.

Windows tend to leak, but not necessarily through thin glass. "Typically, air moves through headers and below sills," Tom says. So, not surprisingly, the infrared camera showed no insulation in the cavities above and below the windows at this house. Torrey then took out a candle-size smoke stick, which emits a wispy column of nontoxic white powder when it's squeezed, to help locate small drafts. When he held it up to the window casing the trail of smoke quickly bent toward the trim and disappeared behind it, telling him that there were uninsulated voids. The renovation plan calls for replacement windows that fit inside the existing frames. But first, Tom will drill a series of ½-inch holes all the way around the inside of the jamb—top, bottom, and sides—so he can inject expanding foam into the cavities.
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