Sash window prices in 2026
Last reviewed: July 2026 · Prices are per window, fitted (supply + installation), incl. VAT
A new sliding sash window costs £700–£2,500 fitted depending on material — uPVC at the value end, hardwood timber at the top. If your original sashes are still sound, you may not need new windows at all: a full refurbishment with draught-proofing runs £250–£500 per window, and slim double-glazed units can be retrofitted into existing frames for £600–£1,100. This guide covers all four routes and when each one makes sense.
Sash window prices by type
| Option | Price per window | Best for |
|---|---|---|
| uPVC sliding sash (new) | £700 – £1,300 | The sash look on a budget, no repainting |
| Timber sash — softwood (new) | £1,100 – £1,900 | Period homes where uPVC is refused or looks wrong |
| Timber sash — hardwood (new) | £1,400 – £2,500 | Longest life, conservation-grade joinery |
| Refurbish + draught-proof original | £250 – £500 | Sound originals that rattle and leak heat |
| Retrofit double glazing into existing sashes | £600 – £1,100 | Keeping original boxes with modern glass |
Bands assume a standard-size opening with normal access. Very tall Victorian openings, bays, horns and glazing-bar details, and upper floors needing scaffold all push jobs towards the top of each band. Multi-window orders come in cheaper per window — the same shared-labour effect as standard window prices.
Repair, retrofit or replace?
- Repair + draught-proof when the boxes and sashes are structurally sound. Draught-proofing alone transforms rattly single-glazed sashes — brush seals in the beads, new cords, balanced weights.
- Retrofit slim double glazing when you want modern thermal performance but the joinery is worth keeping. Slim units (around 12mm) replace the single panes in the existing sashes; weights are rebalanced to suit.
- Replace when timber is rotten beyond economic splicing, boxes have distorted, or you are switching material. A good installer will tell you which windows genuinely need replacing — it is rarely all of them.
What a proper sash window quote includes
- Survey — each opening measured individually; old openings are rarely square.
- Removal and disposal — old windows out and taken away, reveals made good.
- The full window — box or frame, both sashes, balances or weights, beads, furniture and locks.
- Glazing spec in writing — replacement windows must meet the thermal standard in Approved Document L; ask for the U-value on the quote.
- Certification — FENSA or CERTASS self-certification for replacements.
- A written guarantee — typically 10 years on frames and sealed units.
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Frequently asked questions
How much does a sash window cost fitted?
A uPVC sliding sash window typically costs £700–£1,300 fitted, a softwood timber sash £1,100–£1,900, and a hardwood timber sash £1,400–£2,500. That is per window, including removal of the old window, fitting and sealing. Refurbishing an original sash — draught-proofing, new cords and overhaul — is far cheaper at £250–£500 per window.
Is it cheaper to repair or replace original sash windows?
If the boxes and sashes are sound, repair wins comfortably: a full overhaul with draught-proofing runs £250–£500 per window against £1,100+ for a new timber sash. Retrofitting slim double-glazed units into the existing sashes sits in between at roughly £600–£1,100 per window. Replacement makes sense when the timber is rotten beyond splicing or the boxes have moved.
Can I fit uPVC sash windows in a conservation area?
Often not on the front elevation. Many conservation areas have Article 4 directions requiring like-for-like timber replacements, and listed buildings need listed building consent for any window change. Check with your council before ordering — a refused retrospective application can mean removing brand-new windows. Where uPVC is refused, timber sashes or secondary glazing are the usual routes.
Why are sash windows so much more expensive than casements?
The sliding mechanism. A sash window is two glazed frames running in a counterbalanced box — springs or weights and pulleys, staff and parting beads, and far more joinery than a hinged casement. Fitting takes longer too, especially in older openings that are rarely square. Expect a sash to cost roughly 50–80% more than a casement of the same size and material.
Sources: price bands compiled July 2026 from published UK installer price guides (Checkatrade, Which?, FMB cost guides) and cross-checked against regional quote data. Regulations: Approved Document L. Installer certification: FENSA.