Quick Answer
A standard double-glazed timber sash window (900×1500mm, softwood) costs approximately £1,500 supply and fit. Smaller windows from £1,200, larger from £2,000+. Accoya or hardwood adds 30–40%. Triple glazing adds 25–35%.
Price by Window Size
| Window Size | Softwood (DG) | Accoya (DG) | Softwood (TG) |
|---|---|---|---|
| 600 × 900mm | £1,200 | £1,600 | £1,500 |
| 900 × 1200mm | £1,400 | £1,850 | £1,750 |
| 900 × 1500mm (standard) | £1,500 | £2,000 | £1,900 |
| 1050 × 1800mm | £1,800 | £2,350 | £2,250 |
| 1200 × 2100mm (full height) | £2,200 | £2,800 | £2,750 |
Prices include supply, installation, decoration, and removal of old windows. VAT included. Prices as of May 2026.
What Affects the Price?
Size
The single biggest factor. A small bathroom sash window (600×900mm) uses half the timber and glass of a full-height bay window (1200×2100mm). Price scales roughly linearly with area.
Timber Species
Engineered softwood is the standard choice. Kiln-dried, laminated for stability, factory-primed. Good for 30–40 years with regular maintenance (repaint every 8–12 years).
Accoya is modified softwood with hardwood-level durability. Dimensionally stable, rot-resistant, paint holds 2× longer. More expensive but significantly lower lifetime cost. We recommend Accoya for ground floor windows and anywhere exposed to weather.
Hardwood (sapele, meranti, oak) offers natural beauty and durability but costs the most and has longer lead times. Oak is typically used for heritage projects where natural finish is required.
Glazing
Double glazing (4/16/4mm argon-filled) is standard. U-value around 1.4 W/m²K. Essential for thermal performance and noise reduction.
Triple glazing (4/8/4/8/4mm) achieves U-values around 0.8–1.0 W/m²K. Heavier — sash balances need upgrading. Worth it in exposed positions or passive house projects.
Glazing Bars
Plain sash (no bars) is cheapest. 2-over-2 Victorian style adds £80–£120 per window. 6-over-6 Georgian style adds £150–£250 due to the additional joinery work.
Paint Finish
Factory spray-finished in any RAL or Farrow & Ball colour is included. Dual colour (different inside and outside) adds £50–£80 per window.
Get Your Exact Price in 60 Seconds
Our 3D configurator lets you specify exact dimensions, timber, glazing, and colour — and gives you an instant price.
Open the 3D Configurator Book a SurveyHow Much for a Whole House?
| Property Type | Windows | Softwood (DG) | Accoya (DG) |
|---|---|---|---|
| 2-bed Victorian terrace | 6–8 | £9,000–£12,000 | £12,000–£16,000 |
| 3-bed Victorian terrace | 10–12 | £15,000–£20,000 | £20,000–£26,000 |
| 4-bed semi-detached | 12–16 | £18,000–£28,000 | £24,000–£36,000 |
| 5-bed detached | 16–22 | £25,000–£40,000 | £33,000–£52,000 |
What’s Included in the Price?
- Site survey and measurement
- Manufacture in our own workshop
- Factory spray finish in your chosen colour
- Removal and disposal of old windows
- Installation including all making good
- Internal and external decoration
- All ironmongery (locks, handles, sash lifts)
- 10-year manufacturing guarantee
Frequently Asked Questions
How much does a sash window cost to replace?
A new timber sash window costs £1,200–£2,500 supply and fit, depending on size, timber species, and glazing type. A standard 900×1500mm double-glazed softwood sash window is typically around £1,500 installed.
Are sash windows more expensive than casement windows?
Yes, typically 20–30% more. Sash windows have two moving sashes, a box frame with weights or spiral balances, and more complex joinery. A casement window of the same size would cost £1,000–£1,800.
How much do 10 sash windows cost?
For a typical Victorian terrace with 10 standard sash windows, expect £15,000–£25,000 supply and fit for softwood with double glazing. Hardwood or Accoya increases the total by 25–40%.
Does Accoya cost more than softwood?
Yes, approximately 30–40% more. A softwood sash window at £1,500 would be around £2,000–£2,100 in Accoya. The premium buys you 50+ year durability without the need for regular repainting.
Is double or triple glazing worth the extra cost?
Double glazing is essential — it halves heat loss compared to single glazing. Triple glazing adds another 15–20% thermal improvement but costs 25–35% more. For most homes, double glazing offers the best value. Triple is worth it in exposed or north-facing positions.