How to Weatherstrip an Exterior Door, Step by Step

A drafty door is one of the easiest energy fixes in a home. Weatherstripping seals the gaps between the door and its frame, and a door sweep seals the gap at the bottom. This guide follows the job aid the U.S. Department of Energy (DOE) publishes for its Weatherization Assistance Program crews, adapted for a homeowner.

How can you tell if a door leaks air?

DOE’s job aid says visible daylight or loose-fitting exterior doors are common signs of air leakage. Other clues:

• you feel a draft near the door on a cold, windy day,
• the door rattles in the frame when the wind blows,
• old weatherstripping is cracked, flattened, torn or missing,
• there is a gap under the door you can see light through.

Which kind of weatherstripping should you buy?

For the sides and top of an exterior door, kits with a rigid strip (wood, vinyl or metal) that carries a compressible seal and fastens with screws hold up to daily use. For the bottom, a door sweep attaches to the inside face of the door; some thresholds also have a replaceable seal. Buy a kit that matches your door’s height and width, and choose a sweep that fits the door thickness. ENERGY STAR also certifies exterior doors if the door itself is damaged beyond sealing; see our windows and doors guide.

What tools do you need?

• tape measure and pencil,
• a fine-tooth saw or snips to cut and notch the strips,
• a caulk gun and exterior-grade caulk,
• a drill or screwdriver for the screws supplied,
• a screwdriver to tighten hinges and the strike plate.

How do you install door weatherstripping?

1. Adjust the door first. Tighten loose hinges, knobs and strike plates so the door sits evenly in the frame. DOE’s steps make these adjustments before any weatherstripping goes on.
2. Measure. Measure each side of the doorway, and the top, to size the weatherstripping. Measure the door bottom for the sweep.
3. Cut and notch. Cut the pieces to length and notch the ends of each side piece so it meets the top piece tightly, if the manufacturer hasn’t already notched them.
4. Caulk. Apply a thin bead of caulk on the back of the weatherstripping, lined up with the screw holes.
5. Fit and fasten. Press the strip snugly into place against the closed door and fasten it securely with the short screws provided by the manufacturer.
6. Add the sweep. Close the door, set the sweep so its seal touches the threshold lightly, and fasten it.
7. Test. Open and close the door several times. It should latch without forcing. Adjust strips or the sweep as needed. On a windy day, check again for drafts or daylight.

How do professionals test the result?

Weatherization crews verify their work with a blower door (a fan that depressurizes the house) and smoke to show where air still leaks. A home energy audit can do the same for your whole house. Many utilities offer audits; check your utility’s website.

Anything to know in an older home?

If your home was built before 1978, scraping or sanding painted door trim to fit new strips can release lead dust. Use lead-safe practices or hire a lead-safe certified firm; see our lead-safe renovation guide.

What else should you seal?

The same idea applies to windows that open, attic hatches and the door to an attached garage. Moving parts get weatherstripping; gaps around fixed frames get caulk. For heating and cooling equipment, see Wise Home Comfort’s guide to HVAC filters and thermostat upkeep. Door checks are on our fall home maintenance checklist.