Draughty windows are the silent budget-killers of British homes — that cold trickle of air around the frames that makes you nudge the thermostat up another degree. The best way to stop draughts around windows isn’t always new windows (which cost thousands). In most cases, £30–£50 of materials and a weekend’s work gets you 80% of the benefit. Here’s how.

First: find where the draughts actually are

Don’t guess. On a windy day, slowly move a lit candle or incense stick around each window frame — the flame flickers or the smoke streams where air is getting in. Check:

• Around the opening sash (the moving part)
• Where the frame meets the wall
• The sill junction
• Keyholes and trickle vents
• Old sash windows: the meeting rails and the staff beads

Mark the spots with masking tape so you don’t lose track. You’ll often find the worst draughts aren’t where you expected.

The best way to stop draughts around windows: ranked by effectiveness

1. Self-adhesive draught strips (best all-rounder)

Foam or rubber strips that stick to the frame where the sash closes. Cheap (£5–£10 per window), effective, and easy to fit — clean the surface, peel, stick, done. They last 3–5 years before needing replacement. For casement windows, this is usually all you need. Choose the right profile: P-strip for larger gaps (2–5mm), E-strip for smaller ones.

2. Brush strips for sash windows

Traditional sash windows need a different approach — adhesive foam gets shredded by the sliding motion. Brush pile strips fitted into the staff beads and parting beads seal the gaps while letting the sash move freely. A full sash draught-proofing kit costs £15–£25 per window and makes a transformative difference. Our guide to improving security on old sash windows covers the related job of securing them.

3. Sealant for frame-to-wall gaps

Gaps where the frame meets the wall need silicone sealant (exterior grade outside, decorator’s caulk inside). A tube costs £5 and seals several windows. Cut the nozzle small, apply steadily, smooth with a wet finger. It’s not glamorous work but it stops the worst draughts.

4. Secondary glazing

For single-glazed windows you can’t or won’t replace (listed buildings, conservation areas, rented homes), secondary glazing — a discreet extra pane fitted inside the existing window — cuts draughts and noise dramatically. DIY kits start around £100 per window; professional systems £300–£500. Far cheaper than double glazing and often nearly as effective for draughts.

5. Heavy curtains

Not a fix for the draught itself, but floor-length heavy curtains with a pelmet trap a layer of still air against the window and make a real difference to comfort — especially in the evening. Close them at dusk without fail.

6. Window insulation film

Shrink-fit plastic film (the hairdryer kind) creates a secondary glazing effect for about £5 per window. It looks slightly odd up close but it’s nearly invisible from a distance, and it’s a brilliant temporary fix for a single winter — ideal for renters.

What NOT to do

• Don’t seal trickle vents shut. They’re there for ventilation — blocking them causes condensation and mould. Draught-proof around them, not over them.
• Don’t seal every gap in the house. Homes need some ventilation. If you’re draught-proofing extensively, make sure kitchens and bathrooms still have working extractor fans.
• Don’t use expanding foam around window frames internally. It’s messy, hard to remove, and looks terrible. Use proper sealant.
• Don’t ignore condensation. If draught-proofing leads to condensation on windows, you need more ventilation, not less sealing — open trickle vents and use extractor fans.

How much difference does it really make?

Draughts can account for 10–15% of your home’s heat loss. Proper draught-proofing typically saves £50–£120 a year on heating bills — meaning the materials pay for themselves in the first winter. But the real payoff is comfort: no more cold spots by the window, no more curtains billowing on windy nights. It’s one of the highest-satisfaction DIY jobs there is, and a key part of reducing your heating bills.

When draught-proofing isn’t enough

If your windows are single-glazed, rotting, or the frames are warped so badly they don’t close, draught strips are a sticking plaster. At that point, compare the cost of professional draught-proofing and secondary glazing against replacement — our guide to double glazing costs has the numbers. But for the majority of UK homes with basically sound windows, draught-proofing is the smart money.

Draught-proofing doors: the other half of the job

Windows get the attention, but doors leak more. The worst offenders:

• Letterboxes: an unsleeved letterbox is a hole in your door. Fit a brush-sealed letterbox plate (£10–£15) inside and out — or a proper draught-proof letterbox. The difference is immediately noticeable.
• The bottom of the door: brush strips or automatic drop-down seals (£15–£25) close the gap without dragging on the floor. Essential for external doors.
• Around the frame: self-adhesive foam strips, same as windows. Check the seal when the door’s closed — daylight visible around the edges means heat escaping.
• Keyholes: old-fashioned keyholes whistle in the wind. A keyhole cover (£3) or an escutcheon fixes it.
• Cat flaps: the draught champion. Modern magnetic-seal cat flaps (£30–£50) are vastly better than the 1990s plastic flaps. If the cat’s gone, seal it up entirely.

Doors and windows together: a full-house draught-proofing job (materials £80–£120, one weekend) is the highest-comfort-per-pound DIY project there is. Pair it with the measures in our heating bills guide and winter feels like a different season indoors.

How to test your draught-proofing worked

After fitting, verify the results:

• The candle test, repeated: no flicker where you sealed. Any remaining flicker shows gaps you missed.
• The hand test: on a windy day, hold your hand near the sealed frame — you should feel no cold stream.
• The curtain test: curtains near draught-proofed windows should hang still, not billow.
• The bill test: compare this winter’s energy usage with last year’s (adjusting for price changes). A 5–10% drop is typical from draught-proofing alone.

The Energy Saving Trust’s draught-proofing guide has additional detail on materials and professional installation costs if you’d rather not DIY.

The takeaway

The best way to stop draughts around windows is self-adhesive strips for casements, brush strips for sashes, and sealant for frame-to-wall gaps — under £50 for most houses, one weekend’s work, and savings from the first cold snap. Find the draughts with a candle, seal them methodically, and keep your trickle vents open. Your heating bill (and your ankles) will thank you.