Quick answer: Most draughts come from worn gaskets (£8–£20 to fix yourself), dropped hinges (£15–£60 each, fitted), or shrunken brush seals on sash windows (£20–£40 per window). Full window replacement (£300–£700 per window) is only worth it when 5+ windows are draughty AND the frames themselves are failing. This guide shows you how to find the source, fix it the cheapest way that works, and recognise when you’ve hit the point of replacement.
Find the draught source first
Don’t replace anything until you know where the draught actually is. On a windy day, hold a lit incense stick or thin tissue near these spots — wait 10 seconds at each:
- Around the opening sash (the bit that opens) where it meets the frame — most common
- Where the frame meets the wall — sealant or expanding foam has failed
- Around the locks and hinges — hardware has worked loose, frame no longer pulls tight against the gasket
- Through the trickle vent at the top of the frame — that’s by design (Building Regs); some draught is normal here
- Through the keyhole on older locks — easy fix
- Bottom drainage holes — these are SUPPOSED to let water out, not air in. If they’re whistling, the gasket above them has failed.
The location of the draught tells you the fix. Match yours to the right section below.
5 quick DIY fixes (£5–£40)
1. Replace the gasket
The rubber strip around the opening sash compresses 20–30% over its life and eventually cracks. Replacement gasket costs £3–£5 per metre from any glazing supplier (eBay, Screwfix, local trade counter). One window typically needs 4 metres. Push the old strip out with a screwdriver, push the new one in. Takes 15 minutes per window. Best £15 you’ll spend this winter.
Tip: take a 5cm sample of your old gasket to the supplier. There are dozens of profiles and they need to match exactly to seal properly.
2. Adjust or replace hinges
Modern uPVC casement hinges have a 3mm adjustment built in — turn the screw on the hinge body to pull the sash tighter against the frame. If the hinges are worn or damaged, replacement Yale-style friction hinges are £15–£25 a pair on Amazon. Fitting takes 20 minutes per window with a screwdriver.
3. Add foam tape (temporary)
Self-adhesive foam strip, £4–£8 a roll, lasts one winter. Stick it where the sash meets the frame as a stop-gap. Not pretty, but works for an emergency cold snap. Replace properly with new gaskets in spring.
4. Re-caulk the perimeter
Where the frame meets the wall, the original silicone or expanding foam often shrinks or cracks at the 10–15 year mark. Cut out the old, brush out the gap, run a bead of frame-grade silicone sealant (£5–£8 a tube). One tube does 4–5 windows. Use anti-mould silicone if you’re doing this in a kitchen or bathroom.
5. Replace sash brush seals (sash windows only)
Sash windows have brush-strip seals that wear faster than gasket strips on casements. Replacements are £3–£6 per metre. Slot them into the existing channel; no glue needed. £20 fixes a single sash window.
When DIY isn’t enough — paid repair options (£40–£200)
- Hinge replacement by a fitter: £40–£80 per window. Worth paying for if your sash has dropped and you don’t fancy the alignment work.
- Full hardware swap (handles, locks, hinges, espagnolette): £80–£150 per window. Sensible when the window is 15+ years old and multiple bits are worn.
- Professional gasket replacement: £30–£50 per window. Cheap, but DIY does the same job for £5 in materials.
- Frame re-bedding (if the frame has shifted in the wall): £100–£200 per window. Only worth doing if the frame is otherwise sound.
- Sash cord and weight repair (traditional sash windows): £80–£150 per window — needs a specialist.
When to give up and replace the whole window
Some draughts are symptoms of frame failure that no gasket will fix. Time to budget for full replacement when:
- The frame itself is visibly warped, cracked or bowing — gaskets can’t seal an out-of-true frame
- The window is over 25 years old AND draughty AND showing other signs of wear (see our window lifespan guide for the full checklist)
- 5 or more windows are draughty — at that scale, a full-house replacement quote is often within £200 of doing them all individually, and the warranty is consolidated
- The frame has rotted (timber) or the corner welds have failed (uPVC) — both are end-of-life
- You also need new glass for energy or noise reasons — if you’re replacing the IGU anyway, a full window upgrade often pays back faster
Cost ladder — cheapest fix to most expensive
| Fix | DIY cost | Fitter cost | How long it lasts |
|---|---|---|---|
| Foam tape (emergency) | £4–£8 | — | 1 winter |
| Re-caulk perimeter | £5–£10 | £40–£80 | 10–15 years |
| Replace gaskets | £10–£25 per window | £30–£50 | 15–20 years |
| Replace brush seals (sash) | £15–£25 per window | £40–£60 | 10–15 years |
| Hinge swap | £15–£25 per window | £40–£80 | 15–20 years |
| Full hardware swap | — | £80–£150 | 15+ years |
| Frame re-bedding | — | £100–£200 | 20+ years |
| Whole window replacement | — | £300–£700 | 20–35 years |
Common mistakes to avoid
- Don’t seal trickle vents to stop draughts. They’re there for a reason — without them you’ll get black mould within 18 months. Trickle vents have been required by Building Regs Part F since June 2022.
- Don’t use general-purpose silicone on a window perimeter. Use a frame-grade or window-grade silicone sealant — different chemistry, lasts much longer in UV.
- Don’t expand-foam a draughty bottom drainage hole. Those holes are designed to drain water; block them and you create rot inside the frame within a season.
- Don’t pay £150 for a “magic draught-proofing service” that turns out to be a bloke with a tube of foam tape. If it sounds too easy, ask exactly what’s being installed and check it against this guide.
- Don’t believe “lifetime gasket” claims. No gasket lasts a lifetime. 15–20 years is excellent; 25 years is the absolute upper limit.
Frequently asked questions
Will replacing my windows really stop the draughts?
Only if the draughts are coming from the windows. About 30% of “draughty window” complaints turn out to be coming from the wall around the frame, the loft hatch, suspended floors, or unsealed pipework. Worth doing the incense-stick test before committing to £6,000 of new windows.
Is it worth replacing windows just to save on heating bills?
Sometimes. Going from old (pre-2002) double glazing to modern A-rated windows typically saves £100–£250/year on a 3-bed semi at 2026 energy prices. Payback time on a £5,000 install: 20–50 years. The economics only work if your frames are already failing AND you’re staying in the property long-term. For most homes, a gasket-and-hardware refresh is far better value.
My new windows are draughty — can I claim under the warranty?
Yes, if they’re under 5 years old and you can document the draught with the install report. Most manufacturer warranties cover gasket and hardware failure for the first 5 years. If the original installer has gone out of business, your insurance-backed guarantee (if you have one) takes over. Read the small print before paying out of pocket.
Do secondary glazing panels stop draughts?
Yes, very effectively — but they’re a separate solution to the underlying problem. A secondary glazing panel adds an extra layer of glass inside your existing frame, dramatically cutting draughts and noise without replacing the original window. Worth considering for sash windows in conservation areas where you can’t change the original.
Will draught-proofing make my windows mist up between the panes?
No. Misting between panes is a separate failure mode in the sealed glass unit and isn’t affected by external gaskets. See our condensation guide for the full picture.
Get installer quotes for repair or replacement
If you’ve decided DIY isn’t enough or you need full replacement, we’ll connect you with up to 4 vetted local installers within 24 hours. Tell us how many draughty windows you have and your postcode — they’ll handle the rest. Free, no obligation, no pressure.
For a budget figure first, our cost calculator gives you an estimate in 30 seconds — no contact details required.
Sources used: Eco Experts draught proofing guide, Homebuilding & Renovating draught proofing analysis, Anglian Home Improvements draughty windows clinic, FENSA Building Regs Part F (2022 trickle vents update), Glass and Glazing Federation gasket lifespan data, Energy Saving Trust draught-proofing savings figures (2026). Pricing is UK 2026 estimate. Last reviewed: April 2026.
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