Weatherstripping around doors and windows is the single cheapest thing you can do to lower your energy bill. A gap the width of a penny around a standard exterior door is equivalent to cutting a three-inch hole in your wall. Air conditioning and heat pour out through these gaps all year, and the fix costs ten to twenty dollars and takes less than an hour.
Step 1: Find where you are losing air
On a windy day, hold a lit incense stick or a thin piece of tissue near the edges of exterior doors and windows. If the smoke wavers or the tissue moves, that is where air is getting in or out. You can also do this on a cold night with a flashlight, have someone shine a flashlight around the door or window frame from outside while you stand inside in the dark and look for light leaking through.
The most common leak points on doors are the sides (where the door meets the door stop), the bottom (the door sweep or threshold seal), and the top of the door frame. Windows typically leak at the sash meeting rail and at the corners where the frame pieces join.
Step 2: Choose the right weatherstripping type
Foam tape weatherstripping (self-adhesive, available in various widths and thicknesses) is the easiest to install and works well for irregular gaps on windows and older door frames. It compresses when the door or window closes and fills the gap. The downside is it wears out faster than other types, typically two to three years with regular use.
V-strip (tension seal) weatherstripping is a folded piece of metal or plastic that fits into the channel where a door or window slides and creates tension that fills the gap. It lasts longer than foam and is barely visible. Good for the sides of doors and the channels of double-hung windows.
Door sweeps attach to the bottom of exterior doors and seal the gap between door and threshold. These are the most important piece for exterior doors because the bottom gap is usually the largest. A door sweep with a rubber or brush insert drags along the threshold and provides a seal even when the floor is not perfectly level.
Step 3: Install foam tape weatherstripping
Clean the surface where the tape will stick with rubbing alcohol and let it dry, adhesive does not bond to dirty surfaces and will peel off within weeks if the surface is dusty or oily. Measure the length of each side you are sealing, cut the tape to length with scissors, peel the backing, and press firmly along the door stop (the strip the door closes against). Close the door gently to check that the seal compresses without preventing the door from closing fully or latching properly. If the door will not close, the tape is too thick, use a thinner profile.
Step 4: Install a door sweep
Remove the door from the hinges if possible, or leave it in place, most door sweeps can be installed either way. Hold the sweep against the bottom of the door with the rubber or brush edge touching the threshold lightly. Mark the screw hole positions, drill pilot holes slightly smaller than the screw diameter, and drive the screws. Check that the door opens and closes without the sweep catching on the threshold, the seal should drag lightly, not resist the door.
For doors on uneven floors, an automatic door sweep (one that rises when the door opens and drops to seal when it closes) is worth the extra cost. It does not drag on carpets or uneven floors and gives a better seal than a fixed sweep in those situations.
How much this actually saves
The Department of Energy estimates that drafts account for 5 to 30 percent of home energy use. Even at the low end, sealing the worst gaps in a leaky house can take a meaningful chunk off the heating and cooling bill. In a home with old weatherstripping or none at all, the payback on a twenty-dollar door weatherstripping kit is often measured in weeks, not years.
If you are tracking home expenses and looking for the fastest wins that reduce monthly costs, air sealing is at the top of the list. The Broke Mom Home Reset ($17) covers energy-saving fixes like this alongside the broader budget strategies that make them count even more.
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