Air leaks and water infiltration are two of the most damaging forces in a home. They drive up energy bills, promote mold growth, rot wood, and damage finishes — and they’re almost entirely preventable with basic weatherproofing techniques. Caulking and weatherstripping are among the highest-ROI home maintenance tasks you can do in a single weekend.
The U.S. Department of Energy estimates that air leaks account for 25–40% of home heating and cooling costs. The biggest culprits are rarely visible:
To find leaks, do a draft test on a cold windy day. Move a stick of incense or a lit candle slowly around window frames, door frames, and outlets. Smoke that wavers horizontally indicates a draft. You can also feel with a damp hand — much more sensitive to air movement than a dry hand.
Choosing the wrong caulk for the job leads to early failure and water damage. The main types:
The technique matters as much as the product. Poor application leads to ugly, ineffective results.
Cut the tip at a 45-degree angle. Start with a small opening — about 1/8 inch for most applications. You can always widen it, but you can’t make it smaller. A smaller opening gives you more control.
Pierce the inner foil seal with a long nail or the tool on your caulk gun.
Hold the gun at a 45-degree angle to the joint. Squeeze the trigger smoothly and move at a consistent pace. The goal is to deposit a steady, continuous bead slightly larger than the gap — not too thick, not too thin.
Pull the gun along the joint rather than pushing it. This gives you better visibility and control.
Immediately after applying the caulk, smooth and compress the bead into the joint. Professional options:
Even a well-caulked door frame can leak enormous amounts of air if the door itself doesn’t seal tightly. Weatherstripping is the solution.
Hold a piece of paper in the door frame and close the door. Try to pull the paper out. If it slides freely, you have a gap. Do this at multiple points around the frame.
Foam tape: Self-adhesive, cheap, easy to install. Works for moderate gaps but compresses over time. Best for cabinet doors and attic hatches, not entry doors.
V-strip (tension seal): A durable folded strip of metal or vinyl. Installs in the groove of door jambs and provides excellent long-term sealing. Best for the sides of doors.
Door sweeps: Mount to the bottom of the door and seal the gap at the floor. Choose a type that doesn’t drag on carpet. Automatic door sweeps rise when the door opens and drop when it closes — the best option for heavy use.
Door threshold: The strip mounted to the floor that the door closes against. Upgrade to an adjustable threshold with a rubber gasket for the best seal.
Compression weatherstripping: A foam or rubber bulb strip mounted to the door stop. Creates a positive seal when the door closes.
For V-strip on side jambs: Clean and dry the jamb. Cut the strip to length. Insert into the groove with the V facing inward (toward the stop). Tack with the provided nails every 2 inches.
For door sweeps: Position so it just grazes the floor when installed. Too tight and it will drag and wear prematurely. Too loose and it won’t seal.
You can feel the cold through exterior outlets in winter because there’s often no insulation directly behind the switch box.
The fix: Purchase foam gaskets designed to fit behind outlet and switch covers (they cost about 50 cents each). Turn off the circuit at the breaker. Remove the cover plate. Press the foam gasket over the outlet/switch, then reinstall the cover. Takes 2 minutes per outlet and eliminates a significant draft source.
The attic is often the biggest source of air infiltration in a home. Warm air rises and escapes through any gap into the attic, pulling cold air in through lower-level leaks.
Target: Where interior walls meet the attic floor, around recessed lights, around the attic hatch, and where wiring and plumbing penetrate the top plates.
Use expanding spray foam (like Great Stuff) for gaps up to about an inch. For larger gaps, cut rigid foam board to fit and seal the edges with foam. The attic hatch should have weatherstripping around its perimeter and rigid foam insulation attached to its back face.
A single weekend of thorough weatherproofing — caulking, weatherstripping, and outlet insulation — can reduce your energy bills by 10–20% and make your home dramatically more comfortable.