Cold ankles on the sofa, a curtain that moves with the window shut, a hallway you hurry through: that's a draughty house. Knowing how to stop draughts is one of the cheapest ways to feel warmer this winter, and most of the job takes an afternoon and a few inexpensive strips from the hardware shop. The one thing to get right is which gaps to seal and which openings your home needs to stay safe and dry.
First, find where the cold air gets in
Pick a windy day, turn off any fans and wet the back of your hand: cold air is much easier to feel on damp skin. Move slowly around the places where draughts usually start:
- Door frames, the gap under the door, letterboxes and keyholes.
- Window frames, especially on older sash and casement windows.
- Gaps between floorboards and along the skirting boards.
- Holes where pipes come through the wall.
- The loft hatch and any chimney you don't use.
For door and window seals, try the paper test: close the door or window on a sheet of paper. If it slides out easily, the seal isn't working at that point.
How to stop draughts around doors
Doors are usually the quickest win.
- Under the door: fit a brush strip or hinged-flap draught excluder along the bottom edge. A brush strip copes better with uneven floors; a hinged flap lifts as the door opens, which helps if it catches on a mat.
- Around the frame: self-adhesive foam is the cheapest option but wears out sooner than rubber. Clean and dry the surface first, then check the door still closes without forcing it.
- Letterbox: fit a brush or flap on the inside.
- Keyhole: a small swing cover closes it off for very little money.
- Front door still chilly? A heavy floor-length curtain on a pole makes a real difference in a cold hall.
For internal doors, a loose fabric draught excluder (the classic sausage dog) needs no fitting and keeps the cold from the hall out of the living room. If you have a dog or cat, the fabric picks up hair, so run a reusable pet hair remover over it now and then; it works without batteries or refills. If you rent, stick-on strips and loose excluders usually come off easily, but ask your landlord before anything is screwed on or filled.
Seal floorboards, skirting boards and pipes
- Floorboards and skirting boards: use a flexible filler or decorators' caulk rather than a rigid filler, because timber moves. A rug or carpet is the quickest fix of all.
- Pipes: seal the gap in the wall with silicone mastic or wall filler, or expanding foam for larger holes, following the instructions on the can.
- Loft hatch: run a foam strip around the frame so that the hatch closes against it.
Windows have their own guide: how to insulate windows from the cold without building work.
An unused chimney: close it, but not completely
An open chimney you never use lets warm air straight out of the room. A chimney balloon or chimney draught excluder cuts that down, but leave a little airflow so the flue can breathe and moisture doesn't build up. Always take it out before lighting a fire, and leave a clear note on the hearth so nobody forgets. Never fit one in a flue that serves a stove, gas fire or boiler.
What you should never block
Not every gap is a draught. Some of that air is ventilation, which keeps the air fresh and moisture under control. The Sustainable Energy Authority of Ireland (SEAI) points out that rooms with a stove, open fire or gas fire that draws air from the room need a permanent vent for it to be used safely. So never block:
- Air bricks on outside walls, which ventilate the space under timber floors.
- Trickle vents on windows and vents in walls.
- Boiler flues and the permanent vents in rooms with fires or stoves.
- Extractor fans in the kitchen and bathroom.
If you're unsure about a fuel-burning appliance, ask a registered engineer before sealing that room, and keep a working carbon monoxide alarm there. Once you've sealed up, open a window when you shower or cook if you have no extractor fan. If you start to see water on the glass, our guide on how to stop condensation on windows will help.
Where to start
- The gap under the front and back doors, plus the letterbox.
- The door between a cold hall and the living room.
- The loft hatch and any unused chimney.
- Floorboards and skirting boards.
When you've finished, check that your radiators are warming all the way to the top. If they aren't, here's how to bleed radiators.