Window Replacement Costs UK 2026: uPVC, Aluminium & Timber Compared
Real 2026 Prices, Frame Materials, Glazing Options & FENSA Rules
Quick Answer
A standard uPVC casement window costs £450 to £800 fitted in the UK in 2026. Aluminium runs £750 to £1,400, and timber £900 to £2,500. A whole 3-bed semi (8 to 10 windows) is typically £4,500 to £9,500 in uPVC. Always use a FENSA, CERTASS, Assure, or BSI registered installer to keep Building Regs compliance simple. Local installers are usually 20 to 30 percent cheaper than national chains.
New windows are one of the bigger single line items on a UK home. They are also one of the most quote-shopped jobs because the same window can vary by 30 to 50 percent in price between installers. Understanding what is in a quote, and what affects it, is the difference between a fair deal and overpaying by thousands.
This guide covers real 2026 prices for uPVC, aluminium, timber, and composite frames, broken down by window type and property size. It also covers what should be in a quote, the FENSA rules, and when replacement actually makes sense versus simpler repairs.
In This Guide
- 2026 prices for uPVC, aluminium, timber, and composite frames
- Costs by window type: casement, sash, tilt-and-turn, bay, French
- Whole-house replacement costs by property size
- Regional variation across the UK
- What is actually in a window replacement quote
- Glazing options: double, triple, acoustic, self-cleaning
- FENSA, CERTASS and the rules around Building Regs
- Replace versus repair: when each makes sense
Cost by Frame Material
Frame material is the single biggest cost driver. uPVC sits at the bottom, hardwood timber and composite at the top. Aluminium is the modern mid-range option that has grown fast in popularity for extensions and contemporary builds.
| Frame Material | Per Window (1.2m x 1.2m) | Per Window (1.5m x 1.5m) | Lifespan |
|---|---|---|---|
| uPVC | £450 to £800 | £600 to £1,100 | 20 to 25 years |
| Aluminium | £750 to £1,400 | £950 to £1,800 | 30 to 45 years |
| Timber (softwood) | £900 to £1,600 | £1,200 to £2,200 | 30 to 60 years (with maintenance) |
| Timber (hardwood) | £1,400 to £2,500 | £1,800 to £3,200 | 60+ years (with maintenance) |
| Composite (alu-clad timber) | £1,200 to £2,500 | £1,600 to £3,200 | 50+ years (low maintenance) |
Prices include standard double glazing, hardware, and like-for-like installation. Custom shapes (arched, bay, gable) and listed-building specs run higher.
Cost by Window Type
Beyond frame material, the window style affects price significantly. Casement is the most common UK window and the cheapest. Sash windows (vertical-sliding) cost roughly double. Bay and bow windows are the most expensive single units in most homes.
| Window Type | uPVC (mid-range, fitted) | Aluminium (mid-range, fitted) | Timber (mid-range, fitted) |
|---|---|---|---|
| Casement (most common) | £500 to £900 | £800 to £1,400 | £1,100 to £2,000 |
| Sash | £900 to £1,400 | £1,400 to £2,200 | £1,800 to £3,500 |
| Tilt and turn | £700 to £1,200 | £1,000 to £1,700 | £1,400 to £2,400 |
| Bay or bow (3-section) | £1,800 to £3,500 | £2,800 to £5,000 | £3,500 to £6,500 |
| French (double doors) | £1,400 to £2,500 | £2,000 to £3,500 | £2,800 to £4,500 |
| Roof window (Velux-style) | £600 to £1,400 | n/a | £900 to £1,800 |
Whole-House Replacement Costs
Replacing every window at once is 15 to 25 percent cheaper per window than staged replacement, because labour, scaffolding, and certification are all shared across the job. Here are typical UK total costs by property size.
| Property | Window Count (typical) | uPVC Total Cost | Aluminium Total Cost | Timber Total Cost |
|---|---|---|---|---|
| 1-bed flat | 3 to 5 | £1,800 to £4,500 | £2,800 to £7,000 | £3,500 to £9,500 |
| 2-bed flat or terrace | 4 to 7 | £2,500 to £6,000 | £4,000 to £9,500 | £5,000 to £13,500 |
| 3-bed semi | 8 to 10 | £4,500 to £9,500 | £7,000 to £15,000 | £9,000 to £20,000 |
| 4-bed detached | 12 to 15 | £7,000 to £14,500 | £11,000 to £22,000 | £14,000 to £30,000 |
| 5+ bed period property | 15 to 25+ | £12,000 to £25,000 | £18,000 to £35,000 | £22,000 to £55,000+ |
Add £400 to £1,500 for scaffolding if upper-floor windows need access. Period properties with non-standard sizes run 20 to 40 percent above these ranges.
Regional Price Differences
Where you live shifts costs by 20 to 30 percent. London is the most expensive, northern England, Wales, and parts of Scotland are usually the most affordable.
| Region | Single uPVC casement (mid) | Whole 3-bed semi (8-10 windows) | Whole 4-bed detached (12-15 windows) |
|---|---|---|---|
| London | £700 to £1,000 | £6,500 to £14,000 | £10,000 to £22,000 |
| South East | £600 to £900 | £5,500 to £12,000 | £8,500 to £18,000 |
| South West | £550 to £850 | £5,000 to £10,500 | £7,500 to £16,000 |
| Midlands | £500 to £800 | £4,500 to £9,500 | £7,000 to £14,500 |
| North England | £450 to £750 | £4,200 to £8,800 | £6,500 to £13,500 |
| Scotland | £500 to £800 | £4,500 to £9,500 | £7,000 to £14,500 |
| Wales | £450 to £750 | £4,200 to £9,000 | £6,500 to £13,500 |
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What is in a Window Replacement Quote?
A clear quote breaks down every component. Expand each card for what to look for and how it affects the final price.
Glazing Options Compared
The glass itself is roughly 20 to 30 percent of total window cost. Choosing the right glazing for each window matters more than always choosing the most expensive option.
Best for: Most replacement projects, meets current Part L regs
Best for: Cold-facing windows, noise-sensitive homes, Passivhaus standard
Best for: Near busy roads, flight paths, rail lines, urban centres
Best for: Hard-to-reach windows, conservatories, large picture windows
Best for: Required by regs in panels below 800mm, doors, low-level glazing
Best for: Ground floor, side passages, high-risk areas
Quick rule of thumb on glazing
For most UK homes, modern double glazing with low-E coating and argon fill already meets Part L regs and gives most of the benefit. Spend the triple-glazing premium only on north-facing rooms, near sources of noise, or if you are aiming for Passivhaus standards. Acoustic glass is the upgrade that pays back fastest near roads, flight paths, or rail lines.
FENSA, CERTASS & Building Regs
Replacement windows are covered by Building Regulations Part L (energy efficiency) and Part F (ventilation). The simplest way to comply is to use a registered installer who self-certifies the work.
Compliance checklist
- Use a registered installer: FENSA, CERTASS, Assure, or BSI Kitemark are the four main competent person schemes. They self-certify Building Regs compliance.
- Get the certificate: within 30 days of install you should receive a Building Regs Compliance Certificate. Store with property documents.
- U-value compliance: windows must meet a U-value of 1.6 W/m²K or lower (current Part L). All modern double glazing meets this.
- Trickle vents: most replacements now require background ventilation under Part F. Should be included in any quote, not an extra.
- Listed buildings and conservation areas: check with the local council before ordering. Listed Building Consent or planning permission is often required, especially for material changes (timber to uPVC) or pattern changes.
If your installer is not registered
You need to apply for Building Control sign-off separately. This costs £200 to £600 and takes 3 to 8 weeks. More importantly, it will be flagged on a future house sale and the absence of paperwork can hold up the conveyancing process for weeks. There is rarely a good reason to use a non-registered installer.
When to Replace vs Repair
Not every window issue means full replacement. Some classic signs that point one way or the other.
Replace If
- Multiple windows showing condensation between panes
- Single glazing in habitable rooms
- Frames warping, rotting, or cracked at corners
- Whole house is over 25 years from last replacement
- Selling soon and EPC sits at D or below
Repair If
- Single sealed unit failure (re-glaze for £150 to £400)
- Hardware fault (locks, handles) on otherwise sound frames
- Timber frames that need repainting or localised rot repair
- Frames are under 15 years old and otherwise sound
- Listed building where like-for-like repair preserves character
Signs You Should Replace Soon
Condensation between the panes
A clear sign the seal between the panes has failed. Cannot be repaired in most cases. The unit needs replacing (often you can re-glaze without replacing the frame, £150 to £400 per unit).
Single glazing in habitable rooms
Single glazing in lived-in rooms is well below current efficiency standards. Replacement payback through reduced heating bills is typically 8 to 15 years, faster in cold-facing rooms.
Frames warping, rotting, or cracked
Timber rot at the bottom of frames is common in poorly-maintained windows. uPVC frames can crack at corner welds after 20+ years. Localised repair is sometimes possible but usually a sign the whole window is near end of life.
Hardware that cannot be replaced
Modern locks and hinges have standardised fittings that are usually replaceable. Older bespoke hardware (especially on heritage timber) can be expensive or impossible to source. Consider re-glazing with new hardware, or full replacement.
Selling soon and EPC matters
New double or triple glazing can lift an EPC by one full band on a poorly-rated property. If selling within 6 to 12 months, a partial replacement (cold-facing or single-glazed rooms only) may give the best ROI.
Acoustic glass: the upgrade most people skip and regret
If the property is near a busy road, flight path, rail line, or in a dense urban area, acoustic glass is one of the highest-ROI window upgrades available. The 30 to 40 percent premium adds £150 to £400 per window but reduces noise by 5 to 10 dB, which is the difference between hearing traffic and not. Most people who pay for it say it was the single best money spent on the renovation.
Note: only worth fitting on the windows actually facing the noise source. A whole house in acoustic glass is rarely justified.
Key Takeaways
Plan Your Window Replacement Budget
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