Double Glazing: The Complete UK Guide 2025
Costs, window types, top brands, and energy savings – everything you need to know before replacing your windows.
How Much Does Double Glazing Cost?
Prices vary by window style, material, size, and number of windows. Here’s what to expect in 2025:
| Window Style | Per Window (Supply & Fit) | Full House (3-bed, 8–10 windows) |
|---|---|---|
| Casement (uPVC) | £150–£350 | £3,000–£5,500 |
| Sash (uPVC) | £350–£600 | £5,000–£8,000 |
| Casement (Aluminium) | £350–£600 | £5,500–£9,000 |
| Casement (Timber) | £400–£700 | £6,000–£10,000 |
| Bay window (uPVC) | £600–£1,200 | Depends on configuration |
| Tilt & turn (uPVC) | £200–£450 | £4,000–£6,500 |
Double vs Triple Glazing
| Feature | Double Glazing | Triple Glazing |
|---|---|---|
| U-value | 1.2–1.4 W/m²K | 0.6–0.8 W/m²K |
| Cost premium | Baseline | 20–40% more |
| Noise reduction | Good (30–35 dB reduction) | Excellent (35–40 dB) |
| Energy savings | £100–£200/year vs single | £20–£50/year more vs double |
| Worth it? | Essential upgrade from single | Best for new builds, noisy areas, cold regions |
| Weight | Standard | 30–50% heavier – check frames |
Frame Materials Compared
| Material | Cost | Lifespan | Maintenance | Energy Rating | Best For |
|---|---|---|---|---|---|
| uPVC | £ | 20–30 years | Very low (wipe clean) | A+ possible | Best value, most popular |
| Aluminium | £££ | 30–45 years | Very low | A+ with thermal break | Modern/contemporary homes |
| Timber | ££££ | 40–60+ years | High (repaint every 3–5 yrs) | A+ possible | Period properties, conservation |
| Composite | £££ | 35–40 years | Low-medium | A+ | Timber look, less maintenance |
Best Double Glazing Companies
| Company | Type | Materials | Warranty | Price Level | Notable |
|---|---|---|---|---|---|
| Everest | National | uPVC, Aluminium, Timber | 20 years | Premium | Household name, strong warranty |
| Anglian | National | uPVC, Aluminium | 10 years | Mid-premium | UK’s largest window company |
| Safestyle | National | uPVC | 10 years | Budget | Buy one get one free deals |
| Local installer | Local | All | Varies (FENSA backed) | Often best value | Personal service, competitive pricing |
| CR Smith | Scotland | uPVC, Aluminium, Timber | 10 years | Mid-range | Scotland’s largest |
Pros and Cons
Benefits of New Double Glazing
- Reduce heat loss through windows by up to 50%
- Save £100–£200/year on energy bills
- Dramatically reduce outside noise
- Eliminate condensation and draughts
- Improved home security (multi-point locking)
- Boost EPC rating and property value (£5,000–£10,000+)
- Modern styles transform the look of your home
- 20+ year lifespan with very low maintenance
Considerations
- Significant upfront cost (£3,500–£8,000+ for full house)
- Long payback period on energy savings alone (15–25+ years)
- Planning restrictions on listed buildings and conservation areas
- Installation disruption (1–3 days for full house)
- Sales pressure from some national companies
- Cheap installations can have poor fitting and sealing
- Not all uPVC is recyclable
- Timber frames require ongoing maintenance
Energy Ratings Explained
Windows are rated from A++ (most efficient) to E (least efficient), similar to appliances. The rating accounts for heat loss (U-value), solar gain (g-value), and air leakage (L-value).
| Rating | U-Value (W/m²K) | Energy Performance | Building Regs? |
|---|---|---|---|
| A++ | 0.6–0.8 | Net energy gain (triple glazed) | Exceeds requirements |
| A+ | 0.8–1.0 | Very high performance | Exceeds requirements |
| A | 1.0–1.2 | High performance | Meets requirements |
| B | 1.2–1.4 | Good performance | Meets requirements |
| C | 1.4–1.6 | Standard | Minimum for Building Regs |
Tip: Building Regulations require a U-value of 1.4 or lower for replacement windows. Aim for A-rated or above for the best energy performance and savings.
Frequently Asked Questions
Do I need planning permission for new windows?
For like-for-like replacements in England and Wales, no. However, if you’re changing the style, size, or material, or if your home is listed or in a conservation area, you may need approval. Your installer should advise, and all work must comply with Building Regulations (usually certified via FENSA).
What is FENSA and why does it matter?
FENSA is a government-authorised scheme that certifies replacement windows meet Building Regulations. If your installer is FENSA registered, they can self-certify the work. Without FENSA, you’d need a local authority Building Control inspection (adds cost and time). Always use a FENSA or CERTASS installer.
How long does installation take?
A single window takes 1–2 hours. A full house (8–10 windows) typically takes 1–2 days. Bay windows and complex configurations may take longer. Your home will be secure each night – installers finish each opening before moving on.
Can I just replace the glass, not the frames?
If your frames are in good condition, you may be able to replace just the sealed glass units. This costs £50–£150 per window and is worthwhile for misted-up units. However, if frames are warped, damaged, or single-glazed, full replacement is better value long-term.
How do I spot a good quote from a bad one?
A good quote itemises each window, specifies the frame material, glass type, energy rating, and warranty terms. Be wary of quotes that are dramatically cheaper than others (may use inferior products) or those with extreme “today only” discounts. Always get 3+ quotes and check reviews.
Are grants available for double glazing?
The ECO4 scheme provides free or subsidised energy efficiency improvements (including windows) for eligible low-income households. Some local authorities also offer grants. Check the Simple Energy Advice service or your council’s website for current schemes in your area.
Double Glazing Buyer’s Checklist
- Get at least 3 quotes – include both national and local installers
- Verify the installer is FENSA or CERTASS registered
- Choose A-rated or above windows for best energy performance
- Decide on frame material: uPVC (best value), aluminium, or timber
- Check the warranty covers both the glass and the frame
- Ask about security features (multi-point locks, laminated glass)
- Check for planning restrictions if in a conservation area
- Don’t be pressured by “today only” discounts
- Confirm Building Regulations certification is included
- Check reviews on Trustpilot, Checkatrade, or Which? Trusted Traders
Get Double Glazing Quotes
Compare prices from trusted, FENSA-registered installers in your area.