Cost guide
How much do sash windows cost?
Refurbishing a box sash window costs £350 to £750 per window, including new cords, draught proofing and localised rot repair. Replacing one with a new timber sash is £1,200 to £2,500.
Typical prices
| Work | Typical UK price |
|---|---|
| Re-cord one sash window | £150 to £300 |
| Draught proof one window | £150 to £300 |
| Full refurbishment, one window | £350 to £750 |
| Splice out rot, per repair | £120 to £400 |
| New timber box sash, supplied and fitted | £1,200 to £2,500 |
Refurbishment is nearly always cheaper than replacement and in a listed building it may be the only permitted option. Price both before deciding.
What moves the price
- Extent of rot. Cords and beads are quick; splicing a sill or bottom rail is not.
- Draught proofing, usually £150 to £300 per window on its own.
- Size and access. Upper-floor windows need scaffold or a tower.
- Glazing. Retaining original glass costs nothing; slim double glazing adds £400 to £900 per window.
- Listed building or conservation area consent, where required.
What the job involves
A box sash runs on cords over pulleys with cast iron weights hidden in the box on each side. The usual failures are broken cords, painted-shut sashes, worn staff beads, and rot at the bottom rail and the sill where water sits. A full refurbishment takes the sashes out, replaces the cords and re-balances the weights to the sash, splices out any rot with matching timber, re-beads, and fits brush draught seals in the running surfaces.
Questions about sash windows
Is repairing a sash window cheaper than replacing it?
Almost always, and in a listed building or conservation area replacement may not be permitted at all. Refurbishment also keeps the original glass, which is part of the character.
Can sash windows be draught proofed?
Yes. Brush seals in the running surfaces and the meeting rail cut draughts and rattle substantially, and the work is reversible.
Can I get double glazing in a sash window?
Slim units can often be fitted into existing or new sashes. The sash may need deepening and the counterweights re-balanced, and in a listed building it needs consent.