Most old sash windows can be repaired. A good overhaul fixes sticking, rattling and draughts, keeps the original timber and glass, and usually costs a fraction of a new window.
Common sash window problems
- Broken sash cords. The sash drops or won’t stay open. Cords wear through after 20 to 40 years and are the most common repair.
- Sticking or painted shut. Layers of paint, swollen timber or failed pulleys stop the sashes sliding.
- Rattling and draughts. Gaps open up as the beads and sashes wear, letting in cold air, noise and dust.
- Rot. Bottom rails, sills and the lower parts of the box frame are the usual weak spots, because water sits there.
- Loose or cracked glass. Old putty dries out and falls away, and panes crack.
What a full overhaul involves
A specialist removes the staff beads and parting beads, takes out both sashes and checks the box frame. A typical overhaul then includes:
- New cords, with the weights rebalanced so each sash stays where you leave it.
- Easing the sashes: stripping excess paint and planing so they slide freely.
- Timber repairs. Rotten sections are cut out and new wood is spliced in, or resin is used for smaller areas.
- Reglazing loose or broken panes and renewing failed putty.
- Draught-proofing, usually brush seals set into new beads and the meeting rails (see our draught-proofing guide).
- Refitting, then priming and painting the new timber.
Most firms work on one window at a time and refit it the same day, so you are not left with an open hole overnight.
How much does sash window repair cost?
Prices vary with the size of the window, how much rot there is and where you live. London and the South East are at the top of the range. As a rough guide:
| Work | Typical price per window |
|---|---|
| Replacing sash cords | £50 to £160 |
| Basic repair and adjustment | £200 to £350 |
| Repair with draught-proofing | £350 to £600 |
| Full restoration (overhaul) | £600 to £1,000 |
| Rot repair to frame or sash | £200 to £400 |
These figures come from published UK price guides (Checkatrade and MyBuilder, 2026). See the full sash window cost guide for more detail.
Repair or replace?
Repair is usually the better choice when the box frame is sound and the problems are cords, sticking, draughts or localised rot. Original timber is often denser and more durable than modern softwood, and repairs keep the character of the house.
Replacement makes more sense when the rot is widespread, the sashes have been badly altered, or you want double glazing that your existing sashes cannot take. Even then, many firms can fit new double-glazed sashes into your existing frames rather than replacing the whole window.
If your home is listed, you will normally need listed building consent to replace windows, and councils generally expect you to repair first. Repairs that match the original materials do not usually need consent, but check with your council’s conservation officer if you are unsure.
Choosing a repair specialist
- Ask whether they repair or mainly sell new windows. Some firms recommend replacement by default.
- Ask what is included: cords, easing, draught-proofing, painting, and any timber repairs.
- Check whether they splice in new timber or just fill rot.
- Ask how long the guarantee is on the work and on the draught-proofing.
- Look at photos of past jobs on similar houses.
