How do I draught-proof a door?
Sealing the four gaps around a door — bottom, sides, letterbox and keyhole — with the right product for each.
- Difficulty
- beginner
- Time
- 45 min
- Read
- 2 min
Short answer
The gap under a door is usually the biggest single hole in a house. Fit a brush strip or a weather bar at the bottom, compression strip around the frame, a brush cover on the letterbox, and an escutcheon on the keyhole. All four cost very little together.
An external door has four separate leak paths and people usually seal only one. Doing all four takes under an hour, costs very little, and typically makes an immediately noticeable difference to how a hallway feels.
What you'll need
- Brush strip or door bottom seal
- Self-adhesive compression strip
- Letterbox brush cover
- Keyhole escutcheon
- Screwdriver and alcohol wipes
Step by step
- Find the draughts on a cold, windy day with a lit incense stick.The smoke bends visibly where air moves. It finds gaps you would not guess.
- Fit a brush strip or seal to the bottom of the door.Screw-on brush strips are more durable than stick-on. Set the height so it sweeps the floor without dragging.
- Clean the frame with alcohol, then fit self-adhesive compression strip around the sides and top.The adhesive fails on dusty or greasy frames. Choose a thickness that compresses without stopping the door latching.
- Fit a brush cover to the inside of the letterbox.A letterbox is a large, permanently open hole. This is one of the cheapest effective fixes available.
- Fit a covered escutcheon over the keyhole.Small, but a keyhole is a direct hole through the door.
- Check the door still closes and latches properly.Too-thick strip stops it latching, which makes the seal worse rather than better.
- For an internal door to an unheated space, do the same.The door to a garage, cellar or unheated conservatory is worth treating like an external one.
- Leave any trickle vents and air bricks alone.They are designed ventilation. Blocking them causes condensation.
Tips
- A heavy curtain across a front door is genuinely effective and needs no fitting at all.
- Check the door itself has not dropped — a door that no longer closes squarely leaves a gap no strip can seal.
- Do the letterbox first if you only do one thing. It is usually the single largest opening.
Common mistakes
- Sealing only the bottom of the door — There are four leak paths. The letterbox and keyhole are often as significant as the gap underneath.
- Fitting strip to a dirty frame — The adhesive lets go within weeks.
- Blocking vents while draught-proofing — It causes condensation, and near any fuel-burning appliance it is a carbon monoxide risk.
Questions people ask
What is the cheapest way to stop a draughty front door?
A letterbox brush cover, a keyhole escutcheon and a brush strip at the bottom. Together they cost very little and address what is often the largest opening in the house.
Will draught-proofing cause condensation?
Only if you seal deliberate ventilation as well as accidental gaps. Seal around doors and windows; leave trickle vents, air bricks and extractors working.