Seal It Before You Feel It: Finding and Fixing Air Leaks in Your Home
When winter winds start to blow, can you feel the cold air creeping in through cracks and gaps around your home? Small leaks do more than make your house feel drafty—they drive up energy bills, make your heating system work harder, and create uneven temperatures from room to room.
The good news? Most of these air leaks are easy to find—and sealing them is not a project that costs a lot of money or takes a lot of time or expertise. Here’s how to track all of those little leaks down and seal them up before you feel them.
Why Sealing Leaks Matters
Leaving air leaks untreated is like leaving lots of tiny little doors open between your home and the outdoors. According to the U.S. Department of Energy, sealing leaks and adding insulation can cut heating and cooling costs by up to 15 percent.
And sealing leaks doesn’t just save you money. It will make your home feel more comfortable, instantly. That means no more cold spots near windows, no more mysterious drafts by the couch, and no more rooms that never seem to warm up. It can even reduce moisture problems and keeps out dust, pollen, and pests.
Common Sources of Air Leaks
Cold air can sneak in almost anywhere, but there are a few common problem areas worth checking first:
• Windows and doors: Cracks around frames, worn weatherstripping, and gaps at the bottom of doors.
• Attics and basements: Gaps where electrical wires, plumbing, or vents pass through walls or floors.
• Fireplaces and chimneys: Unsealed dampers or cracks around the hearth.
• Outlets and switches: Around electrical boxes on exterior walls.
• Recessed lighting: Gaps around fixtures that allow air to move from uninsulated attic spaces.
• Vents and fans: Areas around exhaust fans, dryer vents, and ductwork joints can develop gaps or loose connections.
How to Find Air Leaks
You don’t need expensive equipment to locate leaks—just do one of these easy tests to check for them:
1. The visual test: Walk around your home looking for visible cracks or gaps, especially where different building materials meet, like around windows, door frames, and foundation walls.
2. The hand test: On a windy day, slowly move your hand around window frames, door edges, and outlets on exterior walls. If you feel cold air, there’s a leak.
3. The candle or incense test: Light a stick of incense or a candle and hold it near doors and windows. If the smoke wavers or is pulled in one direction, you’ve found an air leak.
4. The dollar bill test: Close a door or window on a dollar bill. If it slides out easily, the seal isn’t tight enough.
Watch this video for a step by step tutorial on how to check for air leaks:
How to Fix Air Leaks
Once you know where the leaks are, sealing them up is straightforward. The right fix depends on the size and location of the gap.
• Caulk for small cracks: Use caulk to seal stationary joints around window frames, door casings, baseboards, and where walls meet the floor. Silicone-based caulk is your best bet for areas exposed to moisture, while latex caulk is the go-to choice for interior surfaces that will be painted. If gaps are large, stuff them with caulk saver to cut down on the amount of expensive caulk you need to use.
• Weatherstripping for doors and windows: Replace worn or missing weatherstripping around doors and windows. There are different types—adhesive-backed foam, V-seal, rubber foam, and even products made for specific applications, like patio doors—so choose the one that works best for your job.
• Door sweeps: Install a door sweep or draft stopper at the bottom of exterior doors to block gaps that let in cold air. This video shows you how:
• Outlet and switch gaskets: If cold air is sneaking in through outlets and switches on exterior walls, add foam outlet and switch sealers to block air movement.
• Duct sealing: Wrap ducts in duct insulation to seal gaps in ductwork, especially in attics or crawl spaces where leaks are common.
Don’t Forget the Attic and Basement
Some of the biggest leaks are in places you might not even think about. In attics, seal around light fixtures, plumbing stacks, and attic hatches before adding insulation. In basements, check rim joists, sill plates, and where pipes or wires pass through the foundation.
Check Your Work
Once you’re done, repeat the hand or smoke test in all the problem areas to makes sure you’ve sealed up all the leaks. You should notice a difference in comfort almost immediately.
When to Call a Professional
While most air sealing projects are DIY-friendly, there are times when it makes sense to bring in help. If you’re planning major insulation upgrades, tackling hard-to-reach attic spaces, or want a detailed energy assessment, a professional can conduct special tests to pinpoint issues and recommend fixes. Check with your utility company, too—many of them offer free or low-cost audits and rebates for improvements that you make.
