Windows Guides
Window Replacement Cost UK: What You'll Pay in 2026
Complete UK window replacement cost guide covering uPVC, timber and aluminium windows by size and type.
- uPVC casement window: £350-£600 installed
- Timber casement window: £600-£1,200 installed
- Aluminium casement window: £700-£1,400 installed
- Full house replacement (10-12 windows): £4,000-£16,000 depending on material
Average window replacement costs by material
Window replacement costs vary significantly by frame material, window type, size, and glazing specification. The figures below reflect typical installed costs in the UK as of May 2026, including removal of old windows, supply and installation of new windows, FENSA or Certass certification, and disposal of old materials (Energy Saving Trust, May 2026).
uPVC window costs
uPVC (unplasticised polyvinyl chloride) is the most common replacement window material in the UK, accounting for around 75% of all installations. uPVC windows are affordable, low-maintenance, and thermally efficient. They typically last 20-35 years before degradation or discolouration makes replacement necessary.
| Window type | Size | Cost (installed) |
|---|---|---|
| uPVC casement (single) | 600 x 900 mm | £350-£500 |
| uPVC casement (double) | 1200 x 1200 mm | £450-£600 |
| uPVC tilt-and-turn | 1200 x 1200 mm | £500-£700 |
| uPVC bay window (3-panel) | 2400 x 1500 mm | £1,200-£1,800 |
| uPVC bow window (5-panel) | 3000 x 1500 mm | £1,800-£2,600 |
| uPVC sliding sash (double-hung) | 1200 x 1500 mm | £600-£900 |
Source: Glass and Glazing Federation (GGF) member survey, Q1 2026.
Timber window costs
Timber windows are more expensive than uPVC but offer better aesthetics, particularly for period properties. Hardwood (oak, meranti) costs more than softwood (pine, engineered timber). Timber windows require periodic maintenance (painting or staining every 5-8 years) but can last 30-60 years or more with proper care.
| Window type | Size | Cost (installed) |
|---|---|---|
| Softwood casement (single) | 600 x 900 mm | £600-£900 |
| Softwood casement (double) | 1200 x 1200 mm | £800-£1,200 |
| Hardwood casement (single) | 600 x 900 mm | £900-£1,400 |
| Hardwood casement (double) | 1200 x 1200 mm | £1,200-£1,800 |
| Timber sash window (box sash) | 1200 x 1500 mm | £1,200-£2,000 |
| Timber bay window (3-panel) | 2400 x 1500 mm | £2,500-£4,000 |
Bespoke timber windows for Listed Buildings or Conservation Areas typically cost 30-50% more than standard sizes due to custom joinery requirements.
Aluminium window costs
Aluminium windows are the most expensive option but offer slim sightlines, high strength, and excellent durability (45-60 years). Aluminium frames are thermally broken (insulated internal chambers) to prevent cold bridging. Powder-coated aluminium is available in any RAL colour and requires minimal maintenance.
| Window type | Size | Cost (installed) |
|---|---|---|
| Aluminium casement (single) | 600 x 900 mm | £700-£1,000 |
| Aluminium casement (double) | 1200 x 1200 mm | £900-£1,400 |
| Aluminium tilt-and-turn | 1200 x 1200 mm | £1,000-£1,600 |
| Aluminium sliding patio door | 2400 x 2100 mm | £2,000-£3,500 |
| Aluminium bi-fold doors (3-panel) | 2700 x 2100 mm | £3,000-£5,000 |
Full house window replacement costs
Replacing all windows in a typical UK home (3-bed semi-detached with 10-12 windows) costs:
- uPVC windows: £4,000-£8,000 installed
- Timber windows (softwood): £7,000-£14,000 installed
- Timber windows (hardwood): £10,000-£20,000 installed
- Aluminium windows: £8,000-£16,000 installed
Costs vary depending on the number of windows, their sizes, whether bay or bow windows are included, and regional labour rates. London and the South East typically add 15-25% to the figures above, while Scotland, Wales, and Northern England are typically 10-15% lower.
Most installers offer a discount for full-house jobs compared to individual window pricing. Expect around 10-15% off the sum of individual window costs when replacing 8 or more windows at once.
How A-rating affects window costs
UK windows are rated from A++ (most efficient) to G (least efficient) under the British Fenestration Rating Council (BFRC) Window Energy Rating (WER) scheme. The rating depends on U-value (heat loss), solar gain, and air leakage (BFRC, 2026).
As of May 2026, Building Regulations (Part L) require new windows to achieve a minimum U-value of 1.4 W/m²K, which typically corresponds to a C-rating or better. Most installers now offer A-rated windows as standard, with minimal cost difference:
- C-rated windows: Baseline cost (U-value 1.2-1.4 W/m²K)
- B-rated windows: +£20-£50 per window (U-value 1.0-1.2 W/m²K)
- A-rated windows: +£30-£80 per window (U-value ≤1.0 W/m²K)
An A-rated window saves around £20-£30 per year in heating costs compared to a C-rated window of the same size, assuming a gas-heated home and typical UK weather (Energy Saving Trust estimate, 2026). The upgrade therefore pays back in 2-3 years.
Triple glazing typically achieves A+ or A++ ratings but adds £80-£150 per window. Triple glazing is most cost-effective in exposed locations, north-facing rooms, or new-build Passivhaus and low-energy homes. For most UK retrofit projects, A-rated double glazing offers the best value.
When to replace windows instead of repairing them
Window replacement is a significant investment. In many cases, repair is more cost-effective and environmentally responsible than replacement, particularly for timber windows in period properties.
When to repair
- Timber sash windows in Conservation Areas or Listed Buildings: Historic windows should usually be repaired unless beyond salvage. Draught-proofing, reglaze with slim double-glazing, and repair rotten sections rather than replacing the entire frame (Historic England guidance).
- Structurally sound frames: If the frame is solid and only the glass seal has failed (condensation between panes), you can replace the sealed glazing unit for £80-£150 per window rather than the entire window.
- Minor rot or damage: Small areas of rot in timber frames can be cut out and filled with epoxy resin (£150-£300 per window professionally repaired).
- Hardware issues: Broken hinges, locks, or handles cost £30-£100 to replace and do not require a new window.
When to replace
- Single glazing: Single-glazed windows lose 2-3 times as much heat as modern double glazing. Replacement typically pays back in 10-15 years through energy savings.
- Extensive rot or warping: If more than 30% of a timber frame is rotten or if uPVC frames are warped or cracked, replacement is usually more cost-effective than repair.
- Persistent draughts: If draughts persist after resealing and weatherstripping, the frame geometry has likely failed and replacement is needed.
- Condensation between panes: While the sealed unit can be replaced, if the window is more than 15-20 years old and the frames are also degraded, full replacement is often better value.
- Aesthetic upgrade: If you want to change window style (e.g., replacing uPVC with timber in a period property), full replacement is required.
Additional costs to consider
The quoted window price usually includes removal, installation, and disposal, but some costs may be extra:
- Scaffolding: £400-£800 for a full house if upper-floor windows cannot be accessed safely from ladders.
- Plastering and decoration: Replacing windows often damages surrounding plaster. Budget £50-£100 per window for minor making good, or £500-£1,500 for full redecoration of affected rooms.
- Cill replacement: External window cills (stone, concrete, or timber) may need replacing if damaged or rotten. Costs £40-£120 per cill.
- Cavity closers and insulation: Building Regulations require cavity closers around new window reveals. Most installers include these, but check the quote. Retrofit cavity closers cost £15-£30 per window if omitted.
- Trickle vents: Building Regulations require controllable background ventilation in habitable rooms. Trickle vents are usually included in new windows but check. Retrofit trickle vents cost £10-£25 per vent.
- Listed Building or Conservation Area approval: If planning permission or Listed Building Consent is required, expect £100-£500 for professional drawings and application fees.
How to reduce window replacement costs
Window replacement is rarely eligible for grants in the UK. The ECO4 scheme focuses on insulation and heating for low-income households and does not typically cover window replacement unless windows are in extremely poor condition and the household qualifies under strict criteria.
Ways to reduce costs:
- Replace all windows at once: Full-house replacement reduces per-window costs by 10-15% due to economies of scale and single mobilisation.
- Choose uPVC over timber or aluminium: uPVC costs 40-60% less than timber or aluminium and requires no maintenance. For most homes, modern uPVC offers excellent performance and longevity.
- Stick to standard sizes: Bespoke or non-standard window sizes add 20-40% to costs. Where possible, replace windows with standard sizes to reduce custom manufacturing costs.
- Get three quotes: Window replacement quotes vary by 30-50% between installers. Always get at least three quotes from FENSA or Certass-registered installers.
- Avoid pressure sales: Some national window companies use high-pressure sales tactics and inflated initial quotes followed by "today only" discounts. Independent local installers usually offer better value and service.
- Consider repair instead: For timber windows in period properties, professional repair (draught-proofing, reglaze with slim double glazing, rot repair) costs 40-60% less than replacement and preserves original character.
How to find a reputable window installer
Use only FENSA, Certass, or equivalent Competent Person Scheme registered installers. These schemes ensure installers meet Building Regulations and provide insurance-backed guarantees. Installers registered with these schemes can self-certify compliance, avoiding the need for separate Building Control approval and fees (FENSA, Certass).
To find installers:
- Search the FENSA installer directory or Certass installer directory by postcode.
- Get written quotes from at least three installers. Quotes should specify frame material, glass specification (U-value, A-rating), hardware (locks, hinges), colour, installation timeframe, and guarantee period.
- Check reviews on Trustpilot, Checkatrade, or local community forums.
- Ask for examples of recent work and customer references.
- Ensure the quote includes removal and disposal of old windows, FENSA/Certass certification, and any making good of plaster or brickwork.
Typical guarantees:
- Insurance-backed guarantee: 10 years (required by FENSA/Certass). Covers manufacturing defects and installation faults even if the installer ceases trading.
- Sealed unit guarantee: 10-15 years against seal failure (condensation between panes).
- Frame guarantee: 10-25 years depending on material. uPVC and aluminium typically 10 years, high-quality timber up to 25 years with correct maintenance.
Frequently asked questions
How much does it cost to replace windows in the UK in 2026?
A typical uPVC casement window costs £350-£600 installed. Timber casement windows cost £600-£1,200, and aluminium casement windows cost £700-£1,400. A full house replacement (10-12 windows) typically costs £4,000-£8,000 for uPVC, £7,000-£14,000 for timber, and £8,000-£16,000 for aluminium. Costs vary by region, window size, and specification.
Should I repair or replace my windows?
Repair if the frames are structurally sound and only glass, seals, or hardware need attention. Timber sash windows in period properties should usually be repaired rather than replaced, as repair preserves original character and is more sustainable. Replace if frames are rotten (more than 30% damaged), warped, or single-glazed, if condensation forms between panes and frames are old, or if persistent draughts remain after sealing attempts.
Do A-rated windows cost more than C-rated?
A-rated windows typically cost £30-£80 more per window than C-rated. The difference is minimal, and A-rated windows save around £20-£30 per window per year on heating costs compared to C-rated windows (Energy Saving Trust estimate). The upgrade pays back in 2-3 years, making A-rated windows better long-term value.
How long do replacement windows last?
uPVC windows last 20-35 years before discolouration or degradation makes replacement desirable. Timber windows last 30-60 years with proper maintenance (repainting every 5-8 years). Aluminium windows last 45-60 years or more. Sealed glazing units typically last 15-20 years before seals fail, though the units can be replaced without replacing the entire frame.
Can I get a grant for window replacement?
Window replacement is rarely grant-eligible in the UK. The ECO4 scheme may cover windows in extremely poor condition for low-income, fuel-poor households, but the scheme prioritises insulation and heating measures. Check with your local authority for any regional schemes, though these are uncommon as of 2026.
Do I need Building Regulations approval for window replacement?
Yes, but if you use a FENSA or Certass-registered installer, they self-certify compliance and issue a certificate after completion. You do not need to apply to Building Control separately. If you use an unregistered installer, you must notify Building Control before work starts and pay inspection fees (typically £200-£400).
Will new windows reduce condensation?
Modern double-glazed windows with warm-edge spacers and thermally broken frames significantly reduce condensation compared to old single-glazed or poorly sealed windows. However, condensation on glass is caused by high indoor humidity and poor ventilation. New windows reduce surface condensation but may increase condensation elsewhere (walls, cold corners) if humidity is not controlled. Ensure trickle vents are open and use extractor fans in kitchens and bathrooms.