Why One Gap Can Cost You Hundreds
A ⅛-inch crack around a standard door equals a hole the size of a brick. The U.S. Department of Energy says that sealing such gaps can cut heating and cooling use by up to 20 percent—without touching the thermostat. You feel the chill, the furnace works overtime, and the utility meter spins. Draft-proofing is the fastest payback in home energy saving; most supplies cost less than a pizza.
Tell-Tale Signs Your Door Is Leaking
- You see daylight between the jamb and the door
- A lighter flickers when held near the edges on a windy day
- The floor is inexplicably colder within two feet of the threshold
- Insects or dust bunnies sneak in even when the door is shut
If any box is checked, move on to the fixes.
Tools & Supplies in One Store Trip
- Tape measure
- Utility scissors or tin snips
- Screwdriver (flat or Phillips depending on screws)
- Weather-strip of choice (foam, V-strip, silicone, felt)
- Door sweep or adjustable threshold
- Isopropyl alcohol and rag
- Optional: caulk gun & paintable latex caulk for trim gaps
Total spend: USD 8–25.
Step 1: The Dollar-Bill Test
Close the door on a dollar bill. If it slides out easily with no drag, you have a leak. Test top, sides, and bottom; mark loose spots with painter’s tape so you know where to focus.
Step 2: Pick Your Weatherstrip Style
| Type | Best For | Cost (per door) | Life Span |
|---|---|---|---|
| Adhesive foam | Quick renter fix, uneven gaps | $5 | 1–3 yrs |
| V-strip (tension seal) | Wood or metal jambs, invisible finish | $7 | 3–5 yrs |
| Silicone tubular | Extreme temps, exposure to rain | $12 | 10 yrs+ |
| Felt with metal flange | Paintable historic doors | $6 | 2 yrs |
No type is universal; choose the one that matches your climate and gap size.
Step 3: Prep the Surface
Peel off old sticky strips. Scrape away paint beads or varnish ridges—they create new gaps. Wipe the jamb with isopropyl alcohol so new adhesive bonds firmly. Let it dry two minutes; skip this and the strip curls off in a week.
Step 4: Seal the Jambs and Head
Measure each side, then cut strips ½ inch longer; compress slightly for a snug fit.
- FOAM: Peel backing, start at top, press as you descend. Keep even tension so the strip doesn’t stretch andnarrow.
- V-STRIP: Nail or screw the vinyl flange every 6 inches, with the V opening toward the outside so wind pressure tightens the seal.
- SILICONE: Push the barbed tail into the pre-cut kerf (many jambs have one). If kerf is absent, use the adhesive version like foam.
Close the door and check resistance. The handle should need firm pressure but not a shoulder slam.
Step 5: Fix the Bottom Gap
Floors sag; factory thresholds don’t. Two routes:
Door Sweep
- Measure door width, trim sweep with hacksaw if needed
- Position so the rubber fin just kisses the threshold when closed
- Screw through face or underside—follow product holes
Adjustable Threshold
- Remove screws on top plate, raise or lower until you again feel drag on the dollar bill
- Replace screws; add a bead of silicone underneath if you see daylight through screw slots
Stick-on sweeps exist for renters but wear out faster; still worth it for twelve bucks.
Step 6: Bonus—Lock the Lock
A misaligned strike plate bends the door away from seals. Tighten hinges first. If the latch misses by ⅛ inch, file the plate hole rather than moving the whole plate; touch up with paint pen.
Renters’ 15-Minute Cheat Sheet
No screws, no fuss:
- Use adhesive V-strip on jambs—peels off clean at move-out
- Slide-on fabric draft stopper (the “door snake”) for bottom gap
- Clear removable caulk along outside trim cracks in winter; pull away in spring
Landlords rarely complain because it prevents weather damage.
Invisible Gaps Nobody Checks
Behind Trim
Pull back a section of casing; builders often skip foam here. Shoot low-expansion polyurethane or backer rod plus caulk; replace trim.
Hinge Side
Remove middle hinge pin, slip on a nylon door-hinge seal, tap pin back. It pads the hinge barrel so the door pulls tighter to the stop.
Mail Slots & Pet Doors
Buy a brush-seal mail-slot cover or rigid pet-door flap magnet kit—both snap on with two screws.
When to Call a Pro
- Door is warped and will not seat even after seal swap
- Historic door with fragile glazing or lead paint—disturbing it may break panes or release toxins
- You need to plane wood; taking off too much ruins fire ratings
Otherwise, you have got this.
Care & Re-Check
Each fall, repeat the dollar-bill test. Foam compresses; plastic gets brittle. Replacing a worn strip takes five minutes—cheaper than a service call.
Quick Cost & Payback Summary
- Average US heating season spend: EIA data show space heating is 43 percent of home energy
- DIY seal job: $15
- Potential annual saving: up to 20 percent of that slice
- Payback: usually one season
After that, every winter is profit.
Closing Note
Sealing a door is grunt work, not rocket science. Pick a Saturday morning, queue a podcast, and knock out every exterior entry before lunch. When cold fronts hit, you will sip coffee while neighbors crank their heat—and wonder why you waited so long.
Disclaimer: This article is for general information only; local building codes and rental agreements vary. Consult a licensed contractor for structural issues. Article generated by an AI journalist.