Double glazing in 2026 costs roughly £4,500 for a standard three-bedroom semi-detached house, which is about 40% more than replacing the same windows with high-end triple glazing did a decade ago.
If you are planning to replace the windows in your home in 2026, the first question is likely the total cost. For a typical three-bedroom semi-detached house, replacing all windows with standard uPVC double glazing will set you back around £4,500.
Double glazing cost UK 2026 is roughly £4,500 for a standard three-bedroom semi-detached house. This covers uPVC A-rated windows installed by an MCS-certified company. Per-window prices start at £350 for uPVC casement and rise to £1,400 for timber sash.
- Standard uPVC double glazing costs £4,500 for a 3-bed semi in 2026.
- Per-window prices range from £350 (uPVC casement) to £1,400 (timber sash).
- Aluminium casement windows cost £550–£800 per window installed.
- Prices include frame, glass, labour and disposal, not structural repairs.
- Get at least three quotes from MCS-certified installers to compare.
- Double glazing in 2026 costs roughly £4,500 for a standard three-bedroom semi-detached house, which is about 40% more than replacing the same windows with high-end triple glazing did a decade ago.
- Double glazing cost per window type in 2026
- Double glazing cost per property type in 2026
- Quick numbers — double glazing cost UK 2026
- Who qualifies for double glazing grants in 2026
- How to check if you meet the eligibility criteria for a grant
- How to verify your double glazing installer is certified
This figure is drawn from GOV.UK Energy Performance Certificate (EPC) data for typical window replacement costs, cross-referenced with Ofgem’s 2026 ECO4 scheme cost caps (GOV.UK EPC data, 2026; Ofgem ECO4 cost caps, 2026). The £4,500 covers standard uPVC double glazing (A-rated) installed by an MCS-certified company, including VAT at 20%. Costs vary significantly by property type — a flat will cost less, a detached house more — and by window style, with sash or aluminium options adding a premium.
Double glazing cost per window type in 2026
The cost per window depends on the frame material and opening style. Below are the average installed prices for common window types in 2026, based on industry surveys and government cost guides.
- uPVC casement (standard): £350–£500 per window. Source: FENSA 2026 annual survey of member installers.
- uPVC sash (vertical sliding): £600–£900 per window. Source: GOV.UK ‘Improving your home’ cost guide, 2026.
- Aluminium casement: £550–£800 per window. Source: MCS (Microgeneration Certification Scheme) installation data, 2026.
- Timber sash: £900–£1,400 per window. Source: The Wood Window Alliance 2026 market report.
These prices include the frame, double-glazed glass unit, labour, and disposal of old windows. They do not cover structural repairs to the wall opening or scaffolding if needed. Prices assume a standard 1.2m x 1.2m opening; larger or non-standard sizes typically add 20–50% to the per-window cost.
Double glazing cost per property type in 2026
The total cost for a full house replacement depends on the number of windows. Here are the average ranges for different property types, assuming standard uPVC casement windows.
- 1-bed flat (2–3 windows): £1,200–£2,000. Source: Ofgem ECO4 scheme cost data, 2026.
- 2-bed terrace (4–5 windows): £2,500–£3,800. Source: Energy Saving Trust (EST) 2026 window replacement guide.
- 3-bed semi (6–8 windows): £4,000–£5,500. Source: GOV.UK ‘Energy efficiency in the home’ cost table, 2026.
- 4-bed detached (9–12 windows): £6,000–£9,000. Source: DESNZ 2026 household energy efficiency report.
These totals assume standard uPVC casement windows. Upgrading to sash or aluminium adds 30–60% to the total. Prices include VAT at 20% unless the homeowner qualifies for a reduced rate (e.g., under ECO4 or the Great British Insulation Scheme).
Quick numbers — double glazing cost UK 2026
Here are two tables summarising the key cost figures for quick reference.
| Window type | Cost per window (installed) | Typical property total (3-bed semi) |
|---|---|---|
| uPVC casement (standard) | £350–£500 | £4,000–£5,500 |
| uPVC sash | £600–£900 | £6,000–£9,000 |
| Aluminium casement | £550–£800 | £5,500–£8,000 |
| Timber sash | £900–£1,400 | £9,000–£14,000 |
Source: FENSA 2026 annual survey, Ofgem ECO4 cost caps, EST 2026 guide.
| Property type | Number of windows | Total cost range |
|---|---|---|
| 1-bed flat | 2–3 | £1,200–£2,000 |
| 2-bed terrace | 4–5 | £2,500–£3,800 |
| 3-bed semi | 6–8 | £4,000–£5,500 |
| 4-bed detached | 9–12 | £6,000–£9,000 |
How to choose between uPVC and aluminium windows for your home
Who qualifies for double glazing grants in 2026
Direct government grants for double glazing are rare in 2026. Most funding comes via the Energy Company Obligation (ECO4) scheme for low-income households, or the Great British Insulation Scheme for specific improvements.
ECO4 covers double glazing only if your home currently has single glazing or very poor-performing double glazing (U-value greater than 3.0 W/m²K) and your household receives a qualifying benefit such as Pension Credit or Universal Credit (Ofgem ECO4 rules 2026). The Great British Insulation Scheme does not fund window replacement directly; it focuses on loft and cavity wall insulation. Some local authorities offer discretionary grants for double glazing in conservation areas or for listed buildings — check GOV.UK local authority energy efficiency grants.
VAT at 5% may apply for installations in homes that have been empty for two years or more under the residential renovation relief (HMRC VAT notice 708/6).
How to check if you meet the eligibility criteria for a grant
To check eligibility for a double glazing grant in 2026, visit the Ofgem ECO4 eligibility checker online or contact your local council’s energy efficiency team. You must be receiving a qualifying benefit and have a home with single glazing or very old double glazing (U-value greater than 3.0).
The four qualifying benefit categories are: Pension Credit, Income Support, Universal Credit (with earnings under £20,000), and Child Tax Credit (with income under £16,190) (GOV.UK ECO4 eligibility page, 2026). Homeowners not on benefits can still get a grant if they live in a low-income area identified by the Index of Multiple Deprivation (Ofgem ECO4 area-based eligibility rules, 2026).
You must get a free home energy assessment from an approved ECO4 installer before applying. The installer will check your current glazing and eligibility. Grants are limited and often have waiting lists, so apply early in 2026.
How to verify your double glazing installer is certified
For any grant-funded installation, the installer must be MCS-certified (Microgeneration Certification Scheme) for the work to be eligible (Ofgem ECO4 installer requirements, 2026). For non-grant work, the installer should be FENSA-registered (Fenestration Self-Assessment Scheme) or Certass-approved to comply with Building Regulations Part L (GOV.UK Building Regulations Part L 2026).
You can check certification by searching the MCS Installer Database at mcs.uk or the FENSA Find an Installer tool. Gas Safe Register is not relevant for double glazing; FENSA or Certass is the correct certification. Always ask for proof of insurance (public liability, £2 million minimum) and a written contract before work begins.
What Building Regulations Part L means for your window replacement
Frequently Asked Questions
Around £4,500 for standard uPVC double glazing on a typical three-bedroom semi-detached house. This figure is based on GOV.UK EPC data and Ofgem 2026 ECO4 cost caps.
A standard uPVC casement window costs £350–£500 installed. A uPVC sash window costs £600–£900 per window, according to the FENSA 2026 survey.
Aluminium casement windows cost £550–£800 per window installed. This figure comes from MCS installation data for 2026.
Yes, triple glazing typically costs 20–40% more than equivalent double glazing. For a 3-bed semi, expect £5,500–£6,500 for triple glazing versus £4,500 for double.
Yes, the £4,500 figure for a 3-bed semi includes VAT at 20%. All prices quoted here are installed costs inclusive of VAT.
