Most home energy waste isn’t dramatic. It’s not the old furnace running 24/7 or the windows letting in obvious cold. It’s a slow, steady leak of conditioned air through gaps you can’t see — and the biggest leak in most homes is around the doors.
A standard exterior door has somewhere between 8 and 16 linear feet of perimeter sealed by weatherstripping. After 10 to 15 years (sometimes less if the door faces direct sun), that weatherstripping is compressed, cracked, or hardened to the point where it barely seals. Air moves in and out around the entire perimeter every time the wind blows or the indoor temperature differs from outside — which is constantly.
Most homeowners don’t notice because the leak is small at any given moment. But it runs 24 hours a day for years. Add up all the doors in your house and you’re heating or cooling air that immediately exits through the gaps.
The Candle Test
The fastest way to identify air leaks is a simple test you can do today. On a windy day, hold a lit candle (or a stick of incense) about an inch away from the inside edge of each exterior door, near the frame. Move it slowly along the top, both sides, and the bottom.
If the flame flickers or bends sideways, you have air movement. That’s an air leak.
The same test works on windows. Most homes have leaks all over the place once you start looking.
If the flame flickers, you’re heating the outdoors. The fix is cheap; the energy waste compounds for as long as you ignore it.
What’s Actually Failing
Door weatherstripping comes in several forms, all of which degrade in predictable ways:
Compression foam — soft adhesive-backed strips applied to the door frame stop. Compresses permanently after a few years and stops sealing. Easy to identify visually: the strip looks crushed flat or has gaps where it should be uniform.
V-strip (tension seal) — a folded metal or vinyl strip that springs against the door when closed. Loses springiness over time, especially vinyl. Bends or tears at corners.
Magnetic strip — used on most steel exterior doors and refrigerator-style doors. Loses magnetism over years or gets contaminated with debris. Becomes a passive gasket that doesn’t pull tight.
Door sweep — the rubber or vinyl flap at the bottom of the door. Drags against the threshold every time the door opens. Wears out fast — usually the first weatherstripping component to fail. Visually: cracked, frayed, or bent at angles it shouldn’t bend at.
Threshold seal — the metal-and-rubber piece on the floor under the door. Adjusts up and down on most models. Goes out of adjustment over time and stops contacting the door sweep.
Look at each component. Anything visibly compressed, cracked, frayed, hardened, or missing pieces is failed and should be replaced.
What to Replace First
If you’re going to do one thing, do the door sweep at the bottom of every exterior door. The bottom is where most leaks happen because gravity, foot traffic, and pets all conspire to wear that piece out fastest. Sweeps cost $5 to $15 each and install with a few screws.
After sweeps, replace any obvious failures in the side and top weatherstripping. Compression foam comes in long adhesive rolls for under $15. V-strip is slightly more expensive but more durable.
For aluminum-bottom thresholds with an adjustable insert, sometimes you just need to adjust the threshold up against the sweep. Most have a few hex screws that raise or lower the seal — 30 seconds with an allen key.
The 15-Minute Per-Door Job
- Examine the existing weatherstripping all around the door. Note where it’s failed.
- Remove the failed sections. Most adhesive-backed strip peels off; some leaves residue you can clean with denatured alcohol. Door sweeps unscrew.
- Measure the length you need.
- Cut new weatherstripping to fit. Most come in standard 17-foot rolls. Doors usually need 16 to 18 feet total.
- Apply or install. Adhesive strips press into place; sweeps screw in.
- Test by closing the door. Should feel slight resistance when closing — that’s the seal working. Should be firm but not requiring force.
- Repeat the candle test. Confirm the leaks are sealed.
Most doors are an efficient one-session job — the work is straightforward once you have the materials lined up.
Don’t Forget the Frame Caulking
While you’re inspecting, check the caulking around the exterior frame of each door. Old caulk cracks and pulls away from the siding. A small bead of fresh exterior-grade caulk around the frame perimeter prevents wind and water from getting behind the frame — which is where the worst leaks happen.
If you find missing or failing caulk, scrape it out with a putty knife and apply fresh exterior-grade caulk. Dries in a few hours, works for a decade.
Windows Too
Same principles apply to windows. Operable window sashes have weatherstripping that wears the same way. Older single- or double-hung windows often have visible gaps you can fix with strip weatherstripping. Modern double-pane windows have integral seals that last longer but eventually fail too — usually showing as condensation between the panes (which is a glass replacement, not a weatherstripping fix).
Storm windows, where present, are an additional seal layer that often outperforms anything you can do to the primary window. Worth keeping in good repair.
The ROI Math
Energy auditors typically estimate that air leaks account for 25 to 40% of total heating and cooling energy loss in older homes. Most of that is doors and windows. A few hours of weatherstripping work and a few rolls of $10 strip can meaningfully cut that number.
The math depends on your house, your habits, and your utility rates — but for most West Omaha homes, weatherstripping work pays for itself within a single heating or cooling season. Probably faster.
The Bigger Air-Sealing Picture
Doors and windows are the visible leaks. The bigger ones are usually in places you can’t see — top plates in interior walls, recessed light cans, the rim joist around the foundation, attic access hatches, and gaps around plumbing and electrical penetrations. A blower door test (something an energy auditor performs) can find and quantify all of them.
But weatherstripping is the easiest place to start, and it produces immediate, noticeable improvement. Once you’ve done the doors, the rest is bonus.
Let Your Handy Neighbor Handle It
Door weatherstripping is a Fall task in our seasonal rhythm — right before winter heating starts. We walk every exterior door, run the air leak test, replace failed sections, adjust thresholds, and check frame caulking. Materials billed separately for new weatherstripping and caulk, but installation is part of your visit.
It’s not flashy work. It just makes the house quieter and the energy bill lower.
Want every door in your house actually sealing the way it was designed to? Book your Free Home Assessment.