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Sealing Air Leaks, Step by Step

Gaps and holes allow air—and money—to slip out of homes

Drafts and uncomfortable temperature swings are challenges with many older homes and can be a big energy (and money) waster. In a lot of homes, about half of the conditioned air escapes to the outdoors every hour. The good news is that you can stem the tide on your own with a little time and effort.

Here are three steps to get you started. Keep in mind that there’s much more to learn about sealing your home than we can cover here, so consider researching trusted websites for additional tips and tutorials.

Step 1: Find the Leaks

The first step is a thorough visual inspection of the interior and exterior of your home. Look for gaps and holes in exterior walls, flooring and the ceiling. These will often occur where different building materials meet, such as the top of concrete foundation walls or around windows and doors. Another common source of air leaks is where pipes or wiring penetrate a wall, floor or ceiling. Ductwork located in unheated crawl spaces and attics can also contain air leaks.

Exterior doors and windows that open deserve your attention, too. Open each door or window and place a dollar bill between the door or window sash and the frame. If you can pull the bill out easily when it’s closed again, the seal is not tight enough. Any window that rattles when it’s closed or it’s windy out probably isn’t sealed sufficiently either.

Step 2: Gather the Materials You’ll Need

Here’s a short list of materials to get you started:

Caulk. Waterproof silicone or latex outdoor caulk that’s water-soluble until it cures is recommended, especially if it’s paintable when dry.

Expanding spray foam. One can typically costs $4–$6. This is an effective way to plug leaks, but keep in mind that it can be a bit messy.

Weatherstripping. Prices vary depending on the type and length you need, but there’s a wide variety of weatherstripping options made of vinyl, metal, felt and open-cell foam that work for most situations.

Pre-cut foam socket sealers. For about $3, you can typically purchase a pack of 24 sealers, which can be added to electrical outlets to cut drafts.

Chimney balloon. Prices range from $50 to $90. You may need a chimney balloon if your chimney flue doesn’t seal well. Buy a square or round balloon to match the shape of your flue.

Adhesive plastic window insulation sheets. For $2–$14, these sheets can slow the movement of heat through windows.

Step 3: Do It!

If you are unfamiliar with how to apply any of these materials, check out tutorial videos online. Sealing air leaks is one of the best ways to boost your home’s energy efficiency. Whether you’re a DIY pro or novice, with a few simple steps (and low-cost materials), you’ll be well on your way to a sealed, more efficient home.