1. Exterior Doors
If you can see light or are able to slide a dollar bill around your door, it’s leaking air. Inspect the seals and sweeps at the bottom; if they’re worn, replace them with ones that have pliable sealing gaskets that fit snugly against the threshold. Add weather stripping and foam gaskets around doorjambs.
2. Windows
Use incense as a low-tech leak finder. On a cold, windy day, turn off your heater, turn on any exhaust fans, and hold a lit stick near a window. If the smoke gets pulled outside or blown into the room, you’ve located a leak that needs caulking or weather stripping. Then consider the windows themselves: If you have older single-pane windows, you can insulate them by installing inexpensive low-E glass storm windows. These can reduce heat loss through glass by up to 30%. Plastic film insulator kits are an even more budget-friendly seasonal solution. (A hairdryer is likely required to install.)
3. Attics
Check to see whether your attic access panel or door is insulated. “If it’s uninsulated, it’s basically like an open door,” Schollmeier says. Cut 2-inch-thick rigid foam insulation into three or four panels sized slightly smaller than the door or cover. Glue them onto the covering in layers, then seal around the lip of the opening with rubber weather stripping ($7, The Home Depot).
4. Basements
Rim joists—the band of wood that rests on a basement’s foundation walls—are often left uninsulated. Cut rigid foam insulation to fit against the joist, filling any gaps wider than 1/4 inch with expanding foam. Seal the edges with acrylic caulk ($4, The Home Depot).
5. Small Stuff
Add store-bought foam gaskets ($2, The Home Depot) behind the outlet and switch plate covers on exterior walls. Look around for the places where utilities enter your house. Fill gaps around plumbing or wires with caulk or insulating foam ($14, Walmart).
