Find where the air gets in
With the hall light off, look for light from outside showing round the edges of the door. Then, on a windy day, try these:
- Run the back of a damp hand slowly round the frame, along the bottom, and past the letterbox and keyhole.
- Close the door on a strip of paper at a few points along each edge. If the paper slides out easily, the door isn't pressing against anything there.
- Listen for whistling, and watch for a curtain or coat on a hook moving when the wind gusts.
To size a strip for the edges, wrap a small ball of Blu-Tack or modelling clay in cling film, press it onto the frame where the door closes, and shut the door gently. Open it again and measure how thin the ball was squashed. That's the gap the seal has to fill. Check a few places, because old doors are rarely the same all the way round.
The gap under the door
This is usually the biggest gap. Which fix suits depends on the door and the floor:
- A brush strip screwed along the bottom of the door on the inside. The bristles bend over an uneven floor, a threshold or the edge of a mat, so it suits most front and back doors.
- A weatherbar on the outside face of a door that catches the rain. It throws water clear of the threshold, and many have a brush or rubber seal underneath as well.
- A slide-on excluder, two foam tubes joined by fabric that sit either side of the door. No tools or screws, so it suits renters, though on an outside door it wears where it drags on the mat.
- A fabric "sausage" laid along the bottom. It works, but you have to put it back each time the door opens. Fine as a stopgap.
Measure the door's width and the gap under it at both ends before you buy. Brush strips can be cut to length with a hacksaw.
The edges of the door
On a wooden door, the cold air comes through the gap between the door and the frame stop, the strip of wood it closes against. A self-adhesive strip stuck to the stop fills it. The Energy Saving Trust lists two kinds: foam strips, which are cheap and easy but don't last long, and brush or rubber "wiper" strips, which last longer.
- Choose a strip made for the gap you measured. Too thick and the door won't latch, which strains the lock; too thin and air still gets through.
- Clean the frame with soapy water and let it dry before you stick anything on. Adhesive won't hold on dust or old polish.
- Fit the hinge side as well as the latch side and the top. The hinge side is easy to forget.
The letterbox and keyhole
A letterbox with only an outside flap lets the wind straight through. A brush plate screwed over the opening on the inside stops most of it while still letting post in. Measure the opening, not the outside plate, and check the screw holes won't land on the glass or the lock.
An old-style keyhole is a small hole, but it lets in a steady stream of air. A keyhole cover has a small metal disc that swings down over the hole when there's no key in it.
What to leave alone
- Doors between rooms. The Energy Saving Trust says inside doors shouldn't be draught-proofed: the gap underneath lets air move through the house, which carries moisture away.
- Kitchen and bathroom doors most of all, because that's where the moisture is made. Sealing them pushes the damp into one room, where it ends up on the walls. See black mould on walls.
- Any vent a gas fire, boiler or open fire needs to burn safely. If a room has one, don't seal it until you know where its air comes from; a Gas Safe registered engineer can tell you.
- Trickle vents in the door or window frames. Leave them open.
What it saves
The Energy Saving Trust estimates that draught-proofing the windows, doors and floors of a home in Great Britain saves about £55 a year (about £80 in Northern Ireland). The bigger gain is often comfort: a hallway without a cold draught feels warmer at the same thermostat setting, so you may be able to turn it down. The Trust puts the saving from turning the thermostat down from 22°C to 21°C at about £120 a year.
Heating cost per hour Compare what an hour of heating costs with gas, oil, a heat pump or a plug-in heater.Our picks
Chosen by what each product does against the gaps above, from the makers' specs. We haven't tested them ourselves.
For the gap under most outside doors
Stormguard Aluminium Brush Bottom Door Seal (838mm)
- Type
- Door brush strip
- Size
- 838mm, cut to fit
- Seals gaps
- up to 25mm
A brush in an aluminium carrier that screws along the bottom of the door and seals gaps up to 25mm, so it copes with most uneven floors and thresholds. It's 838mm, cut to fit; Stormguard makes longer ones for wider doors.
For a door that catches the rain
Stormguard XRD Rain Deflector with rubber seal (914mm)
- Type
- Weatherbar
- Size
- 914mm, cut to fit
An aluminium weatherbar with a rubber seal underneath, screwed to the outside face of the door. Stormguard says it suits doors that open inwards or outwards. It's 914mm, cut to fit.
For the edges of a wooden door
tesa INSULATION Rubber Weatherstrip S (E-profile)
- Type
- Seal strip
- Size
- 6m
- Seals gaps
- 1 to 3.5mm
- Lasts
- up to 8 years
A self-adhesive rubber strip for gaps of 1 to 3.5mm, which tesa rates to last up to 8 years, far longer than foam. If your Blu-Tack test showed a wider gap, tesa's size L (Amazon) covers 2 to 5mm. tesa says it may leave adhesive behind when you take it off, so ask first if you rent.
For the letterbox
Stormguard PVC Brush Letterplate
- Type
- Letterbox brush
- Size
- 335 x 75mm, for openings up to 279 x 45mm
Twin brushes on the inside of the letterbox stop the wind blowing straight through. It covers openings up to the size in its specs, so measure yours first.
For the keyhole
Stormguard Key Hole Cover (chrome effect)
- Type
- Keyhole cover
Stormguard makes this cover for the keyholes of traditional mortice locks, to cut draughts and rain coming through. Check it's the right size for your keyhole before you order.
No tools, or if you rent
Everlasting Comfort Twin Under-Door Draught Excluder
- Type
- Door excluder
- Size
- Fits doors 76 to 91cm wide
Slides onto the bottom of the door with a foam tube either side, so there's nothing to screw in or stick on. Check the width suits your door.
For windows, see draught excluders and window film. For a front door that opens into the living room, a heavy curtain on a rising rod helps too: see do thermal curtains work?
Sources
Checked 24 October 2026.