Why Draughts Cost You More Than You Think

A chilly draught around a window frame or under a door is more than a minor annoyance. It is a sign that the warm air you have paid to heat is escaping and cold air is taking its place. In a typical UK home, gaps around windows and doors can add up to the equivalent of leaving a small window open all winter. The good news is that most of these gaps are simple to find and cheap to fix, often with tools you already own.

This guide walks you through the practical side of draught-proofing: spotting the culprits, choosing the right material for each job, and fitting it neatly so it lasts.

Finding the Gaps

Before you buy anything, spend half an hour working out where the cold air is actually coming from. Draughts are sneaky and rarely where you expect.

• The tissue test: on a windy day, hold a single sheet of tissue near window frames, door edges and letterboxes. Any flutter tells you there is movement.
• The candle test: a lit tea light held carefully near a suspected gap will flicker. Never do this near curtains or loose paper.
• Check the usual suspects: the gap between a window frame and the wall, the meeting point of opening casements, sliding sash channels, the bottom of external doors, letterboxes, keyholes and cat flaps.
• Look up and down: gaps under windowsills and behind skirting boards are common in older properties.

Make a note of each gap and roughly how wide it is. Most standard draught excluders suit gaps of 3–7mm; anything wider may need a different approach.

Draught-Proofing Windows

Windows are usually the biggest offender, especially in period homes with original timber frames or metal Crittall-style windows.

• Self-adhesive foam tape: the cheapest option, ideal for gaps of 2–5mm around opening casements. Clean the frame first, press it into place, and avoid stretching it as you go. Foam compresses over time, so expect to replace it every couple of years.
• EPDM or rubber seals: slightly pricier but far more durable. These work well on uPVC and aluminium frames where foam tends to peel.
• Brush seals: best for sliding sash windows, where the brush allows the sash to move while blocking the draught. Fit them into the channel so they brush against the sash, not jam it.
• Silicone sealant: for gaps that never need to open, such as where the frame meets the wall. Use a low-modulus, paintable sealant and smooth it with a damp finger for a tidy finish.
• Secondary glazing film: a clear plastic sheet taped to the frame and shrunk tight with a hairdryer. Surprisingly effective on single-glazed windows, and it comes away cleanly in spring.

Draught-Proofing Doors

External doors take a battering, so choose materials that can cope with being stepped over and slammed.

• Brush or wiper strips: screw or stick these to the bottom of the door. The brush type copes well with uneven thresholds; a rubber wiper suits a smooth, level sill.
• Threshold seals: an aluminium carrier with a rubber insert that screws to the floor. Measure the door width carefully and cut the carrier with a hacksaw.
• Perimeter seals: fit foam or rubber strips into the rebate of the door frame so the door closes against them. Check the door still latches easily afterwards.
• Letterbox: a brush flap on the inside face makes a real difference. Fit it so the flap falls naturally closed.
• Keyholes and cat flaps: a simple keyhole cover or escutcheon with a brush seal takes minutes to fit.

Fitting It Neatly

• Clean and dry: wipe surfaces with a damp cloth and let them dry fully. Adhesive sticks badly to dust, grease or damp.
• Mind the temperature: most tapes want a surface above about 10°C. On a cold morning, warm the frame with a hairdryer on low first.
• Measure twice, cut once: cut slightly long, then trim to fit rather than stretching the strip.
• Keep the opening working: never seal a window or door shut. Test every latch, lock and handle after fitting.

Do Not Forget Ventilation

Making a home airtight brings its own problems. Kitchens and bathrooms need to shed moisture, and gas appliances need a supply of fresh air. Keep trickle vents open, do not block air bricks, and open a window for a few minutes each day to change the air. If you have a gas boiler, fire or cooker, never seal up a permanent ventilator — that is a safety issue, not a draught.

Once you have tackled the obvious gaps, you will notice the difference quickly: fewer cold spots, less noise, and a heating bill that is a little kinder. Start with one room, get the hang of it, then work your way around the house.