Draft Stoppers: Five-Minute Window and Door Fixes

Start by identifying the leak: on a closed door or window, hold a lit candle or incense stick near the edges and watch for a steady flicker at the gap. Measure the widest visible gap with a tape measure; many common gaps are 1/8 in to 1/2 in (3–12 mm). For gaps under about 1/4 in (6 mm), adhesive-backed foam tape or felt usually does the job. For larger gaps—over 1/4 in but under 3/4 in (6–19 mm)—use compressible V-strip or tubular silicone weatherstripping. For thresholds and bottom gaps of exterior doors, install a door sweep sized to the door width and trimmed to fit.

Tools and timing: a tape measure, scissors or utility knife, a screwdriver, and a clean rag are the main tools; optional items include a caulk gun and cleaning solvent. Most fixes take about 5 minutes for a single window sash and 10–20 minutes for a door sweep installation. Collect materials first—measuring, cleaning, and test-fitting usually consumes 2–5 minutes of that time.

Materials by gap size: 1) 1/8 in (3 mm) gaps: 3/16 in adhesive foam tape; 2) 1/4 in (6 mm) gaps: V-strip (adjustable compression); 3) 1/2–3/4 in (12–19 mm) gaps: tubular silicone or rubber bulb weatherstripping; 4) under-door gaps 1/4–1 in (6–25 mm): adjustable door sweep with a vinyl or rubber flap. Choose closed-cell foam for durability outdoors and felt or thin foam for interior sash stops.

Quick how-to for adhesive foam: clean the frame with isopropyl alcohol and let it dry (about 2 minutes). Measure the perimeter length, cut the tape 5 mm longer, peel the backing, and press firmly. If the sash still binds, remove 1–2 mm from the foam thickness or switch to thinner tape. Expect adhesive foam to last 1–3 years on interior windows and up to 2 years on protected exterior frames.

Measure before you buy: for a door sweep, measure the door width from edge to edge and the gap under the door at three points (left, center, right). Use the largest of the three measurements to size the sweep; if the gap is 1/2 in (12 mm) in the center but 3/16 in (5 mm) at the edges, trim the sweep to match the center or plan to plane the door by 1–4 mm if clearance is tight. A standard metal-mounted sweep is cut with a hacksaw; vinyl flaps are trimmed with scissors.

Installing a door sweep: clean the underside of the door and mark the screw holes with a pencil while holding the sweep flush. Pre-drill pilot holes with a 1/16 in (1.5 mm) bit for wood doors to avoid splitting. Attach the sweep with the included screws, then slide in the vinyl or rubber seal and test by closing the door—there should be light contact across the bottom without forcing the latch to bind. Re-check the gap: aim for a continuous seal that compresses by about 1–2 mm when the door closes.

Replacing window sash or frame weatherstripping: remove old stripping by peeling or prying gently with a putty knife. Clean the channel with a rag and alcohol to remove adhesive residue—allow 2–5 minutes to dry. Cut the new strip to length, align it, and press into the channel using even pressure. For V-strip on sliding sashes, overlap the two strips by about 10–15 mm at corners to maintain continuity and prevent wind tunnels.

Sealing remaining frame cracks: use a paintable silicone or acrylic-latex caulk for gaps larger than 1/8 in (3 mm) between trim and wall. Apply a continuous bead, smooth with a wet finger or caulk tool, and allow 24 hours to cure for silicone or 4 hours for most acrylic-latex products. For gaps into masonry, use a polyurethane or masonry-specific caulk with 24–48 hour cure times; follow manufacturer instructions for temperature limits (commonly above 40°F / 4°C).

Testing the job: after installing, do a smoke test with incense or a candle on a calm day; a slight, steady pull indicates a remaining leak. For a quantitative check, place an infrared thermometer along the edge and look for temperature drops of 2–5°F (1–3°C) versus surrounding surfaces; any reading over 5°F (3°C) indicates a significant leak. Rework problem areas by adding another strip, tightening screws, or applying caulk.

Maintenance and expected lifespan: adhesive foam typically lasts 1–3 years, V-strip 3–5 years, and a properly installed metal sweep 5–10 years. Check seals annually at the start of heating season and replace worn compressible materials when you notice thinning of 2 mm or more. Keep spare 1 m rolls of foam tape and a spare door sweep on hand for quick same-day fixes.

Further reading: Why Do Door Hinges Squeak? Oiling Them Quiet · How to Soundproof a Thin-Walled Rental Bedroom
Sources: This Old House