Quick Answer: How Much Does Double Glazing Cost?
Double glazing for a full UK house typically costs £3,500 to £10,000 depending on the number of windows, frame material, and glazing specification. Individual window replacement costs roughly £300 to £800 per window installed, with uPVC frames at the lower end and timber or aluminium frames costing more.
Double Glazing Cost by Frame Material
| Frame Material | Cost per Window (Installed) | Lifespan | Best For |
|---|---|---|---|
| uPVC | £300 to £600 | 20 to 35 years | Most homes, budget friendly |
| Aluminium | £450 to £900 | 35 to 45 years | Contemporary properties, slim sightlines |
| Timber | £600 to £1,200 | 25 to 40 years with maintenance | Period and listed properties |
| Composite (timber/aluminium) | £700 to £1,400 | 35 to 45 years | Premium finish, low maintenance |
Whole House Double Glazing Cost Estimate
| Property Type | Typical Number of Windows | Estimated Total Cost |
|---|---|---|
| Terraced house | 6 to 8 | £2,500 to £6,000 |
| Semi detached house | 8 to 10 | £3,500 to £8,000 |
| Detached house | 10 to 14 | £5,000 to £10,000+ |
Double Glazing Cost by Window Style (and the Hidden Extras)
Frame material is only half the price story. The style of each window often moves the cost more than the material does. A standard casement window in white uPVC is the cheapest option to manufacture and fit, so installers use it as the baseline when pricing a job. Every other style adds hardware, glass area or fitting time on top of that baseline.
| Window Style | Typical Cost Per Window (Fitted) | Why It Costs That Much |
|---|---|---|
| Casement (standard, approx. 1.2m x 1.2m) | £350 to £600 | Simple hinged design, standardised manufacture, quick fitting |
| Tilt and turn | £400 to £700 | More complex dual action hardware than a basic casement |
| Sliding sash | £600 to £1,100 | Sliding mechanism, counterbalance, precision fitting, often bespoke sizing |
| Bay (3 to 4 panels) | £1,200 to £2,800 | Multiple linked frames, corner posts, structural support, longer fitting time |
These ranges assume standard white uPVC. Aluminium adds roughly 25 to 50 percent over uPVC for the same style, while timber can more than double the cost. Coloured foils or woodgrain finishes typically add 10 to 20 percent, and oversized or bespoke units can add 20 to 50 percent to the cost of a standard size. Glass upgrades such as acoustic, laminated security or solar control glass push prices higher still, while switching to triple glazing usually adds 15 to 30 percent.
The figure that catches most homeowners out is not the window price itself but the extras around it. Scaffolding for upper floor access typically costs £300 to £800 per elevation. Waste removal or skip hire for a whole house job runs £200 to £350. Making good internal plasterwork and repainting reveals adds roughly £50 to £100 per window. If your installer is not registered with FENSA or CERTASS, building control fees of £200 to £400 apply. Some quotes include all of these and some include none, which is exactly why two quotes for the same job can sit £1,500 apart. Always ask for an itemised breakdown covering supply, fitting, disposal, finishing and certification before you compare.
What Affects the Cost of Double Glazing?
Window Style and Opening Type
Casement windows, which open on hinges, are generally cheaper than tilt and turn windows or sash windows, which involve more complex mechanisms and hardware.
Glazing Specification
Standard double glazing units are the baseline cost, while upgrading to triple glazing, acoustic glass for noise reduction, or security laminated glass will all add to the price, sometimes significantly.
Number and Size of Windows
Larger windows and bay or bow window configurations cost more than standard sized windows, both in materials and the additional labour involved in fitting.
Property Access and Age
Listed buildings or those in conservation areas may require specific window styles or materials to meet planning restrictions, and older properties with non-standard openings can add cost through bespoke sizing.
Do You Need Planning Permission for Double Glazing?
Most double glazing replacement in England falls under permitted development and does not need planning permission, provided the replacement windows are similar in appearance to the originals. Listed buildings and properties in conservation areas often have additional restrictions, sometimes requiring specific glazing bar patterns or materials to preserve the property’s character.
Building Regulations and FENSA Certification
All replacement windows in England and Wales must comply with Building Regulations for thermal performance and safety. Installers registered with FENSA or a similar competent person scheme can self certify this compliance, saving you from needing a separate building control application, so checking for FENSA registration is a sensible step when choosing an installer.
Double Glazing Repair vs Full Replacement
Not every double glazing issue requires full window replacement. A failed seal causing condensation between the panes, known as a blown unit, can often be repaired by replacing just the glass unit within the existing frame, which is significantly cheaper than a full window replacement, provided the frame itself is still sound.
| Issue | Repair Option | Typical Cost |
|---|---|---|
| Blown unit (misted glass) | Replace glass unit only | £80 to £200 per unit |
| Faulty hinges or handles | Replace hardware | £30 to £100 |
| Damaged seals | Reseal or replace seals | £50 to £150 |
| Frame damage or rot | Full window replacement | £300 to £1,200+ |
Energy Savings From Double Glazing
Upgrading from single glazing to modern double glazing can meaningfully reduce heat loss through windows, which typically account for a significant proportion of a home’s total heat loss. While exact savings depend on your current windows, property size, and heating patterns, most homeowners see a noticeable reduction in draughts and heating bills after a full double glazing upgrade.
Frequently Asked Questions
How long does double glazing installation take?
A single window can often be replaced within a day, while a full house of 8 to 10 windows typically takes two to four days depending on complexity and any structural adjustments needed.
Is triple glazing worth the extra cost over double glazing?
Triple glazing offers a modest further improvement in thermal and acoustic performance over double glazing, but the additional cost often takes many years to recoup through energy savings alone, so it tends to suit specific priorities like noise reduction or very cold locations rather than being a universal upgrade.
Can you get grants for double glazing in the UK?
Various government energy efficiency schemes have offered support for double glazing at different times, with eligibility criteria that change periodically, so it is worth checking current government energy schemes directly before assuming you do or do not qualify.
What is a blown double glazed unit?
A blown unit occurs when the seal between the two panes of glass fails, allowing moisture to enter and causing permanent misting or condensation between the panes that cannot be cleaned from either side.
Do I need FENSA certification for a DIY double glazing installation?
If you install replacement windows yourself rather than through a FENSA registered installer, you will need to notify your local council building control department directly to ensure the work is compliant, which involves an inspection and additional fee.
How much does a single double glazed casement window cost in the UK?
A standard uPVC casement window costs roughly £350 to £600 supplied and fitted in 2026. Aluminium versions of the same size run £550 to £800, while timber casements start around £800 to £1,000. Larger sizes, non standard colours and upgraded glass can push a uPVC casement toward £1,250 or more.
Are sash windows really twice the price of casement windows?
Nearly. Fitted sliding sash windows typically cost £600 to £1,100 in uPVC, around double the £350 to £600 for an equivalent casement. The sliding mechanism, balance weights or springs, tighter manufacturing tolerances and more precise fitting all add labour and material cost. Heritage box sash designs in hardwood can reach £2,500 to £3,500 per window.
Why do bay windows cost so much to double glaze?
A 3 to 4 panel bay typically costs £1,200 to £2,800 in uPVC because you are replacing multiple linked frames, corner posts, a wide cill and often structural supports, not a single rectangular unit. Fitting takes considerably longer than a flat window. Bays in poor structural condition or with decorative interior boards needing restoration cost more again.
What hidden costs should I budget for with double glazing?
Budget for scaffolding (£300 to £800 per elevation), waste removal (£200 to £350 for a whole house), making good plasterwork and repainting reveals (£50 to £100 per window), and building control fees (£200 to £400 if the installer is not FENSA registered). A contingency of £500 to £1,000 over the window prices covers most of these.
Do double glazing quotes usually include removing the old windows?
Not always. Fitted quotes from reputable installers generally cover removal and disposal of old frames, but some cheaper quotes exclude it or charge separately. The same applies to making good internal and external finishes. Ask explicitly whether removal, waste disposal and finishing are included before comparing quotes, as these omissions are the most common reason a cheap quote balloons later.
Does double glazing cost more in London and the South East?
Yes. Labour costs in London and the South East typically run 15 to 25 percent above the national average, and restricted parking, congestion charges and difficult access on terraced streets can add further cost. The same window specification that costs £4,000 to £6,000 for a 3 bed semi elsewhere can reach £5,000 to £8,000 or more in the capital.
Expert Insight
Glazing installers frequently point out that homeowners often replace an entire window when only the glass unit has failed, paying considerably more than necessary. Getting a specialist glazing repair quote before committing to a full replacement can identify cheaper repair options where the frame itself remains in good condition.
Final Thoughts
Double glazing costs vary significantly based on frame material, window style, and specification, but understanding these factors makes it much easier to compare quotes accurately and avoid paying for a full replacement when a simpler repair would do. Always check for FENSA registration and confirm exactly what is included in any quote before committing.
Getting quotes for double glazing? Ask each installer to itemise frame material, glazing specification, and installation separately, so you can compare like for like across different companies.
Related Guides
- Types of Windows: A Complete Guide
- Composite Doors: Complete Buying Guide
- Window Boards and Sills: Complete Guide
Written by the HometoWorld editorial team, covering home improvement, renovation, and property maintenance across the UK.
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