Sealing air leaks saves on utility bills

Nobody wants to spend good money to heat the outdoors. But that’s what you could be doing if your house has excessive air leaks.

The more air that flows in through little cracks, holes and gaps in your home’s exterior, the more you have to heat — or, in summer, cool. When that conditioned air escapes to the unheated attic or the outside, you’ve wasted energy and money.

Home energy experts say sealing those openings is one of the most cost-effective ways to cut your heating and cooling bills. Best of all, it can decrease drafts and make your home more comfortable.

Following are common sources of air leaks in the home and methods for sealing them. It’s not a complete list, but it covers leaks that are reasonably easy for do-it-yourselfers to handle.

Only you know your capabilities, however. Some jobs may be better left to a pro.

It’s also worth noting that air sealing goes hand in hand with insulation, which stops heat loss but not air flow. That’s a separate topic, but it’s one worth exploring if you want to minimize your energy costs and make your home more comfortable.

We compiled the information with help from David Gordon, Gary Canter and David Schiever of HomeEnergyMD and its parent company, Regency Window Co. in Twinsburg, Ohio; Matt Pickston of Pro Energy Consultants of Sagamore Hills, Ohio; and the government’s Energy Star program.

—Windows and doors: Air often enters the home through spaces around window frames, window sashes and exterior doors. Adding weatherstripping and door sweeps allows windows and doors to seal more tightly. Various types of weatherstripping are available, including adhesive foam strips, gaskets and spring-type seals.

Caulking around window and door casings stops air that may enter through gaps that are hidden by the trim. Use paintable caulk, and choose clear caulk for woodwork that’s varnished or painted a color other than white.

—Baseboards: Cold air can seep in through gaps between the floor and wall that are covered by baseboards. That’s true even on interior walls, because cold air often travels through wall cavities. A telltale sign of an air leak is dirt on the carpet near the baseboard, deposited there by the moving air.

Run a bead of caulk along the joint between the baseboard and the wall to block the leak. You can also caulk between the baseboard and the floor, if it’s not carpeted.

—Electrical outlets and light switches: In both exterior and interior walls, air can leak around the electrical boxes that hold outlets and switches. Hardware stores and home centers sell flexible foam seals designed to stop those leaks. Just remove the cover over the outlet or switch plate, slip on the seal and replace the cover.

Plugging the outlets with baby-proofing plugs will further stanch the air flow.

—Fireplace: Fireplace chimneys are notorious sources of air leaks. Closing the damper helps, but it doesn’t seal the opening tightly.

You can create a better seal by installing an inflatable chimney balloon, especially if you use your fireplace infrequently. The balloon has a part that hangs down into the firebox to remind you to remove it before you start a fire.

—Exterior walls: Wherever pipes, wires or vents enter or leave your house, air can, too. Seal smaller openings with caulk and larger gaps with a minimally expanding spray foam sealant.

—Basement ceiling: Any penetration in your basement ceiling is a place where air can enter wall cavities. Look for pipes, wires and other systems going through the ceiling, and seal the spaces around them with caulk or spray foam. For bigger openings, cover with foam board and seal the board in place with caulk.

—Sill plate: The sill plate is the plank at the top of the basement walls where the foundation meets the house framing. In most homes that plate is topped by a band of lumber called a rim joist.

Gaps are common here and can be sealed with caulk or minimally expanding foam. Or you can cut rigid foam insulation to fit over the rim joist cavities and then seal the insulation in place with caulk.

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—Vent stack: The vent stack — the pipe that runs up from your drain system and out through your roof — is one of the common places where warm air escapes from your living space into the attic. Electrical lines, plumbing pipes and ducts are other common penetrations where air can leak.

Leaks into the attic aren’t just wasteful; they can also warm the roof, causing snow to melt. That melting snow can refreeze along the colder edges of the roof in potentially damaging ice dams.

Seal the spaces with caulk or spray foam. For openings larger than 3 inches, cover with foam board and seal the board in place with spray foam.

Be careful with chimney or furnace flues, however. Because they get hot, gaps around them need to be covered with metal flashing and high-temperature caulk.

—Dropped soffits: These boxed areas often have a top or back that’s open to the attic or wall cavity, letting cold air in. The opening can be covered with reflective foil or rigid foam, sealed in place with caulk.

—Attic hatch: Warm air often escapes into the attic through the hatch.

Seal that opening by applying foam weatherstripping around the edges of the cover. When the hatch cover is closed, its weight will press down on the foam.

—Recessed lights: Can lights that extend into the attic are another place where warm air commonly leaks. Heat from the light bulb can make the problem even worse.

One do-it-yourself method is to cover the part of the fixture that extends into the attic with a foam bait box or a box made from drywall or Thermo-Pan, a foil-faced cardboard. Seal the box to the attic floor with either caulk or sealing foam.

It’s important to note, however, that not all fixtures are IC rated, meaning they’re safe for insulation contact. Ignoring that could put you at risk for fire, which is why the people at HomeEnergyMD think sealing recessed lights is a job better left to the professionals.

Unless you’re sure the fixture is IC rated, it’s important to leave at least 3 inches between the fixture and the box.

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Want to know more about air sealing? Energy Star has a helpful publication, A Do-It-Yourself Guide to Sealing and Insulating with Energy Star. You can find it by going to www.energystar.gov and typing “sealing guide” into the search box.

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©2011 the Akron Beacon Journal (Akron, Ohio)

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