The average cost to replace double glazing in a UK home in 2026 is £4,500–£6,500 for a standard three-bedroom semi-detached house, based on EST and Checkatrade data.
If your windows are old, draughty, or damaged, you may be considering a full replacement. The cost varies significantly based on your home and the materials you choose.
The average cost to replace double glazing in a UK home in 2026 is £4,500–£6,500 for a standard three-bedroom semi-detached house, based on industry data from the Energy Saving Trust and Checkatrade (Energy Saving Trust, 2026; Checkatrade, 2026). This range covers the supply and professional installation of uPVC, aluminium, and timber frames. The Department for Energy Security and Net Zero (DESNZ) notes that a typical three-bed semi has around 12–15 square metres of glazing (DESNZ, 2026). Your final cost will depend on your property type, the number of windows, and the frame material you select.
How frame material affects the total replacement bill
The frame material you choose is the single biggest factor in the final price. Different materials have different upfront costs and long-term maintenance needs.
- uPVC: £3,000–£5,500 (average £4,500) for a three-bed semi. uPVC is the most common and cheapest option, with low maintenance and good insulation performance (Checkatrade, 2026; MyGlazing, 2026).
- Aluminium: £5,000–£8,000 (average £6,500) for a three-bed semi. Aluminium frames are stronger and slimmer than uPVC, offering a modern look, but they cost more (Checkatrade, 2026).
- Timber: £6,000–£10,000 (average £8,000) for a three-bed semi. Timber frames are the most expensive and require regular painting or staining, but they offer high thermal performance and a traditional appearance (MyGlazing, 2026).
The Energy Saving Trust notes that all three materials can achieve similar U-values (a measure of heat loss) when fitted with modern double glazing, but timber and aluminium typically have a longer lifespan (Energy Saving Trust, 2026).
Quick numbers what you will pay per window and per home type
The table below shows typical costs and installation times for different window types, frame materials, and home sizes. All figures include supply and fitting by a FENSA-registered installer.
| Window type | Frame material | Home type | Low cost (£) | High cost (£) | Average cost (£) | Installation time (hours) |
|---|---|---|---|---|---|---|
| Casement (standard) | uPVC | 1-bed flat (3 windows) | 1,200 | 2,200 | 1,700 | 6–8 |
| Casement (standard) | Aluminium | 3-bed semi (8 windows) | 5,000 | 8,000 | 6,500 | 12–16 |
| Sash (traditional) | Timber | 4-bed detached (12 windows) | 9,000 | 15,000 | 12,000 | 20–30 |
| Tilt-and-turn | uPVC | 3-bed semi (8 windows) | 4,500 | 6,500 | 5,500 | 14–18 |
Costs and installation times sourced from Checkatrade and FENSA (Checkatrade, 2026; FENSA, 2026). Prices exclude scaffolding, disposal of old windows, and structural repairs.
The direct answer double glazing replacement cost in 2026
The typical cost to replace double glazing in a UK home is £4,500–£6,500 for a three-bedroom semi-detached house. This figure is the most commonly searched range for the keyword “double glazing replacement cost”. The cost includes frames, glass, and professional installation by MCS-certified fitters. It does not include scaffolding, disposal of old windows, or structural repairs such as fixing rotten timber surrounds. For a one-bedroom flat, expect to pay £1,200–£2,200, while a four-bedroom detached home can cost £9,000–£15,000 (Energy Saving Trust, 2026; Checkatrade, 2026).
How much you can save on energy bills with new double glazing
New double glazing can reduce heat loss through windows by around 50% compared to single glazing. However, if you already have older double glazing, the savings are smaller.
The Energy Saving Trust estimates annual savings of £100–£175 for a typical semi-detached house when upgrading from single glazing to A-rated double glazing (Energy Saving Trust, 2026). For a detached house, savings can reach £195–£250 per year. If you are replacing old double glazing with new, the savings are lower, typically £30–£60 per year. The payback period for energy savings alone is 25–65 years, depending on the property size, existing glazing, and fuel costs under the 2026 Ofgem energy price cap (Ofgem, 2026).
The real payback when replacement makes financial sense
Energy savings alone rarely justify replacing double glazing. The payback period of 25–65 years is longer than the typical lifespan of many window frames. However, replacement can make financial sense for other reasons.
Nationwide Building Society reports that new double glazing can increase a home’s value by 3–5% (Nationwide, 2026). Replacement also reduces outside noise, eliminates drafts, and improves comfort. The most cost-effective time to replace windows is when existing frames are rotting, leaking, or single-glazed. In these cases, the cost of repair may be close to the cost of replacement, and new windows will provide immediate comfort and energy benefits. If your current double glazing is in good condition but old, you may want to focus on other energy-efficiency measures such as loft insulation or cavity wall insulation, which offer shorter payback periods.
Eligibility and certification how to verify your installer
In England and Wales, replacement windows must comply with Building Regulations. You must use an installer registered with a competent person scheme such as FENSA or CERTASS (GOV.UK, 2026). These schemes self-certify that the work meets legal standards, avoiding the need for a separate building control inspection.
If you are applying for any energy-efficiency grant, your installer should also hold MCS certification (Microgeneration Certification Scheme) for energy-efficient glazing (MCS, 2026). Check the MCS register to confirm certification. For additional consumer protection, look for TrustMark accreditation, which covers quality assurance and dispute resolution (TrustMark, 2026). Always ask for a written quote and a contract before work begins.
What the 2026 grant landscape covers for double glazing
There is no universal government grant for double glazing replacement in 2026. The Great British Insulation Scheme (GBIS) does not cover window replacement (GOV.UK, 2026). The Energy Company Obligation (ECO4) may fund double glazing replacement, but only for low-income households with inefficient heating systems and where the property has single glazing or very poor existing windows (Ofgem, 2026).
ECO4 eligibility is means-tested and depends on your household income and receipt of certain benefits. Even if eligible, the grant may only cover part of the cost. The DESNZ confirms that no other central government grants are available for double glazing in 2026 (DESNZ, 2026). Some local authorities offer discretionary grants, but these are rare and vary by area. Check your local council for energy efficiency grants
If you are not eligible for ECO4, you will need to fund the replacement yourself. Consider getting at least three quotes from FENSA-registered installers to compare prices and ensure you receive a fair deal. Compare quotes from certified window installers
Frequently Asked Questions
The average cost is £4,500–£6,500 for a standard three-bed semi-detached house in 2026, according to Checkatrade and the Energy Saving Trust. Your final price depends on frame material and number of windows.
uPVC is the cheapest option, costing £3,000–£5,500 for a three-bed semi, per Checkatrade data. It offers low maintenance and good insulation for the price.
Aluminium frames cost £5,000–£8,000 but are stronger and slimmer than uPVC, giving a modern look. The Energy Saving Trust says they also have a longer lifespan than uPVC.
Timber frames can last over 30 years with proper maintenance, according to MyGlazing. They cost £6,000–£10,000 but require regular painting or staining.
Yes, new double glazing can improve energy efficiency and kerb appeal, potentially increasing property value. The Energy Saving Trust notes that modern frames achieve similar U-values to older triple glazing.
