Sash Window Replacement Cost
What it costs to replace all sash windows in a UK house, broken down by property type, with timber vs UPVC pricing and ECO4 grant eligibility.
Replacing sash windows costs £900-£2,200 per window for timber or £600-£1,400 for UPVC, fully installed with double glazing. A typical terraced house (10 windows) costs £9,000-£18,000 for timber or £6,000-£11,000 for UPVC. Semi-detached houses (14 windows) cost £12,600-£26,000 timber or £8,400-£15,400 UPVC. ECO4 grants fund £600-£1,800 per window for eligible low-income households. Listed buildings require like-for-like timber and listed building consent.
Last reviewed: 2026-07-20 • 8 min read • Verified against 12 contractor quotes
Sash Window Replacement Cost by House Type
Full house replacement costs vary by number of windows and access requirements. Prices below are supply and fit including scaffold, disposal, and making good (January 2026).
| Property Type | Window Count | Timber (Softwood) | UPVC |
|---|---|---|---|
| Terraced (2-bed) | 8-10 windows | £7,200-£18,000 | £4,800-£11,000 |
| Terraced (3-bed) | 10-12 windows | £9,000-£22,000 | £6,000-£13,200 |
| Semi-detached | 12-14 windows | £10,800-£26,000 | £7,200-£15,400 |
| Semi-detached (large) | 14-18 windows | £12,600-£32,000 | £8,400-£19,800 |
| Detached (4-bed) | 18-22 windows | £16,200-£40,000 | £10,800-£24,200 |
| Detached (5-bed+) | 22-30 windows | £19,800-£54,000 | £13,200-£33,000 |
What's included: Survey, removal of old windows, new double glazed sash windows, installation, external scaffold (two-storey properties), making good reveals and sills, skip hire, disposal, VAT at 20%.
Not included: Internal decoration (add £200-£400 per window for repainting reveals and architraves), Listed building consent fees (£100-£300), planning application fees if required (£206 householder).
Sash Window Replacement Cost Breakdown
Understanding what makes up the total cost helps you compare quotes accurately. Here's the breakdown for a single standard window (1200×1400mm).
| Cost Component | Timber Softwood | UPVC |
|---|---|---|
| Sash window unit (supply only) | £620-£880 | £450-£680 |
| Removal of old window | £60-£90 | £60-£90 |
| Installation labour | £180-£250 | £140-£180 |
| Making good (reveals, sills) | £40-£80 | £40-£80 |
| Disposal | £20-£35 | £20-£35 |
| Total per window | £920-£1,335 | £710-£1,065 |
Scaffold costs (for whole house, not per window): £400-£800 for standard two-storey terrace or semi. £800-£1,400 for three-storey or bay-heavy Victorian property. £1,200-£2,200 for large detached house. Divided across all windows, this adds £40-£120 per window on average.
Timber vs UPVC: Full House Comparison
Choosing between timber and UPVC affects upfront cost, maintenance, and longevity. Here's the 25-year total cost comparison for a 10-window terraced house.
| Cost Over 25 Years | Timber Softwood | UPVC |
|---|---|---|
| Initial purchase + install | £14,000 | £9,000 |
| Repainting (4 cycles @ £2,500) | £10,000 | £0 |
| Re-cording (year 18) | £1,400 | £0 |
| Balance replacement | £0 | £1,200 |
| Gasket replacement (year 20) | £0 | £800 |
| Total 25-year cost | £25,400 | £11,000 |
| Saving with UPVC: £14,400 over 25 years for a 10-window house | ||
UPVC wins on 25-year cost. Timber wins if you plan to keep the house 50+ years (timber frames last 80+ years with maintenance, UPVC needs full replacement after 25-35 years), or the property is listed.
ECO4 Grants for Sash Window Replacement
The ECO4 scheme funds energy-efficient window replacement for eligible households. If you qualify, grants cover £600-£1,800 per window (average £1,200).
Who Qualifies for ECO4?
You must meet both criteria:
- Income under £31,000 household annual income, or receiving Universal Credit, Pension Credit, JSA, ESA, Child Benefit (3+ children), or other means-tested benefits
- Energy Performance Certificate (EPC) rating D-G (most properties with single glazed sash windows are E-G)
Listed buildings and conservation area properties can apply if they meet income criteria, but must use approved heritage-compliant windows (usually slim double glazed timber, not UPVC).
How Much Does ECO4 Cover?
| Scenario | Grant Amount | Your Contribution |
|---|---|---|
| Full grant (lowest incomes) | £1,200-£1,800/window | £0 |
| Partial grant (moderate incomes) | £600-£1,200/window | £300-£800/window |
| No grant (income over £31k) | £0 | Full cost |
Check eligibility at simpleenergyadvice.org.uk or call 0800 444 202. ECO4 runs until March 2026 with extension likely (historically renewed every 3-4 years).
Listed Building Sash Window Replacement
Listed buildings (Grade I, II*, or II) require listed building consent before replacing windows. This affects material choice, cost, and timeline.
What Listed Building Consent Requires
- Like-for-like replacement: New windows must match original design, materials, and glazing bar pattern. UPVC is almost always refused.
- Slim double glazing: Standard 24mm DG changes sightlines and is often rejected. Use 14-18mm slim DG or vacuum glazing (6mm).
- Authentic hardware: Traditional sash fasteners, cords not spiral balances, authentic horns and mouldings.
- Heritage paint: Linseed oil paint often required (more expensive than modern acrylics, £400-£600 per window).
Listed Building Sash Replacement Costs
| Spec | Cost per Window |
|---|---|
| Hardwood sash + slim 18mm DG | £1,800-£2,600 |
| Hardwood sash + vacuum glazing | £2,200-£3,200 |
| Listed building consent (per application) | £100-£300 |
| Heritage paint finish (linseed oil) | +£400-£600/window |
A 10-window listed terrace costs £22,000-£32,000 for compliant hardwood replacement with slim DG. Some listed building owners choose full restoration instead (£600-£1,200 per window), keeping original frames and retrofitting slim DG or secondary glazing.
Replace vs Restore: Decision Guide
Replacement isn't always the right choice. Sometimes restoration makes more sense financially or is required by planning.
Replace If:
- Box frames are rotten beyond 40% of timber volume (uneconomic to repair)
- Sashes have failed mechanically (severe warping, multiple broken joints)
- Property is not listed and not in a conservation area front elevation
- You want the lowest maintenance option (UPVC)
- Restoration quote exceeds 75% of replacement cost
Restore If:
- Listed building (any grade)
- Conservation area front elevation
- Original sashes are pre-1900 with historical value
- Frames are fundamentally sound (less than 30% rot)
- You're planning to keep the property 40+ years
Restoration costs £600-£1,200 per window including sash removal, timber repair or replacement, cord renewal, draught proofing, slim DG retrofit or reglazing, repainting. Total house cost for 10 windows: £6,000-£12,000.
How Long Do Replacement Sash Windows Last?
| Material | Lifespan | Maintenance |
|---|---|---|
| Timber softwood (pine, redwood) | 60-80 years | Repaint every 5-7 years |
| Timber hardwood (oak, accoya) | 80-120 years | Repaint every 7-10 years |
| UPVC | 20-35 years | Wipe clean, no painting |
Timber sash windows are repairable at end of life (replace rotten sills, re-glaze, repaint). UPVC sashes are replaced entirely when balances or frames fail after 25-35 years.
Sources
Pricing verified against:
- Checkatrade full house sash replacement quotes (Jan 2026, 12 installers, regional pricing)
- MyBuilder supply-and-fit timber sash quotes (London, Southeast, Midlands, 2025-2026)
- FENSA average replacement window costs (Dec 2025 report)
- ECO4 scheme grant values (Ofgem guidance, updated Dec 2025)
- Historic England listed building consent requirements (Oct 2025)
- The Sash Window Workshop trade price list (hardwood and softwood, Jan 2026)
Related Guides
- Wooden Sash Windows Cost — timber material and species comparison
- UPVC Sash Windows Cost — UPVC pricing and longevity
- Double Glazed Sash Windows Cost — slim DG retrofit vs replacement
- Sash Window Refurbishment Cost — when to refurb instead of replace