How much does double glazing cost?

The average cost of double glazing a 3-bedroom semi-detached house is £4,000–£7,500, depending on window style, frame material, and installer. Individual window prices range from around £300–£600 for a standard uPVC casement window (including fitting) to £800–£1,500+ for larger bay or sash windows. uPVC is the cheapest option, aluminium costs 20–40% more, and timber is the most expensive. Getting at least 3 quotes from different installers is essential.

How much can double glazing save on energy bills?

According to the Energy Saving Trust, replacing single-glazed windows with A-rated double glazing in a typical 3-bedroom semi could save around £195–£235 per year on energy bills. The savings are larger for bigger or less insulated homes. If you're replacing old double glazing with modern A-rated or triple glazing, savings are smaller (around £50–£100/year) since the old windows already provided some insulation. Payback period for double glazing is typically 15–25 years on energy savings alone.

Is there a government grant for double glazing?

Double glazing is generally NOT covered by the main government energy efficiency schemes (like Great British Insulation Scheme or ECO4), which focus on insulation and heating. However, some local council grants may cover replacement windows, especially in conservation areas or for vulnerable households. In Scotland, Home Energy Scotland may offer grants. If your windows are directly linked to a heating upgrade (e.g. as part of a whole-house retrofit), there may be some support. Always check with your local council and Home Energy Scotland/Nest (Wales).

Do I need planning permission for double glazing?

Usually no — replacing windows is permitted development, so you don't need planning permission. However, there are exceptions: listed buildings (you'll need listed building consent), conservation areas (restrictions may apply, especially for front-facing windows), and flats (may need freeholder consent). All replacement windows must comply with Building Regulations and must be installed by a FENSA or CERTASS-registered installer, or you'll need to get a building control sign-off.

Double Glazing Costs & Savings UK — 2026 Price Guide | PocketWise

Replacing old windows with double glazing is one of the most common home improvements. Here’s what it costs, what you’ll save, and what to watch out for.

Average Double Glazing Costs

By Property Type

Property	Number of windows (typical)	Cost range (uPVC)
1-bed flat	3–5	£1,200–£3,000
2-bed terraced	6–8	£2,500–£5,000
3-bed semi	8–12	£4,000–£7,500
4-bed detached	12–18	£6,500–£12,000
5-bed detached	15–25	£8,000–£18,000

By Window Type

Window type	Price per window (supply + fit)
Casement (standard)	£300–£600
Tilt and turn	£350–£700
Sash (sliding)	£600–£1,200
Bay window (3-panel)	£1,000–£2,500
Bow window	£1,200–£3,000
French doors	£800–£1,500
Patio doors (sliding)	£900–£2,000

By Frame Material

Material	Cost comparison	Pros	Cons
uPVC	Cheapest (baseline)	Low maintenance, good insulation, 20+ year lifespan	Can look plasticky, fewer colour options traditionally
Aluminium	20–40% more than uPVC	Slimmer frames, modern look, very durable, recyclable	Less insulating (needs thermal break), more expensive
Timber	40–80% more than uPVC	Traditional look, excellent insulation, paintable	Needs regular maintenance, prone to rot if neglected
Composite (timber/aluminium)	50–100% more than uPVC	Timber inside, aluminium outside — low maintenance + natural look	Most expensive option

Energy Ratings

Rating	Performance	Energy saving
A++	Best available	Maximum savings
A+	Excellent	Very high savings
A	Very good (minimum recommended)	High savings
B	Good	Moderate savings
C	Minimum Building Regulations standard	Lower savings

Always choose A-rated or better — the difference in price is small but the savings over 20+ years are significant.

Energy Savings

Replacement scenario	Estimated annual saving (3-bed semi)
Single glazing → A-rated double	£195–£235/year
Old double glazing → A-rated double	£50–£100/year
Single glazing → triple glazing	£235–£280/year
Old double glazing → triple glazing	£80–£140/year

Source: Energy Saving Trust estimates

Payback Period

Scenario	Total cost	Annual saving	Payback period
Replacing single glazing (3-bed semi)	£5,000	~£215	~23 years
Replacing old double glazing	£5,000	~£75	~67 years

Note: Payback is based purely on energy savings. Double glazing also adds property value (typically £5,000–£10,000+), reduces noise, improves security, and makes your home more comfortable — these non-financial benefits often justify the investment.

Double Glazing vs Triple Glazing

Feature	Double glazing	Triple glazing
Panes	2	3
U-value (lower = better)	1.0–1.4	0.6–0.8
Cost	Baseline	20–40% more
Annual saving over single	~£215	~£255
Weight	Standard	Heavier — may need stronger frames
Noise reduction	Good	Excellent
Best for	Most homes	New builds, passive houses, very cold areas, noise-sensitive locations

Grants and Financial Help

Scheme	What it covers	Who qualifies
Great British Insulation Scheme	Insulation (NOT usually windows)	Certain council tax bands and income criteria
ECO4	Insulation and heating (NOT usually windows)	Low income, benefits, fuel poverty
Local council grants	Some councils offer window grants	Check with your council
Home Energy Scotland	Grants for energy efficiency improvements	Scotland residents
Nest (Wales)	Energy efficiency advice and grants	Wales residents on low income
Green Deal (residual)	Pay over time via energy bill savings	Still available for some measures
VAT reduction	0% VAT on some energy-saving materials	Must meet specific criteria

Note: Most government schemes focus on insulation and heating, not replacement windows. However, if you’re receiving other funded improvements, windows may sometimes be included as part of a whole-house approach.

How to Choose an Installer

Check	Detail
FENSA or CERTASS registered	Essential — they self-certify Building Regulations compliance
Get 3+ quotes	Never accept the first quote
No high-pressure sales	Reputable installers don’t pressure you
Check reviews	Trustpilot, Google Reviews, Checkatrade, Which? Trusted Traders
Written guarantee	At least 10 years on frames, 5 years on glass units
Insurance-backed guarantee	Protects you if the installer goes bust
Full written quote	All costs itemised — no hidden extras
Survey before quoting	They should measure and inspect, not quote over the phone
Deposit	No more than 25% — pay the balance on completion

Common Problems to Avoid

Problem	How to avoid it
Condensation between panes	Indicates seal failure — should be covered by guarantee
Draughts	Poor installation — insist on proper sealing and check on first cold day
Misting	Seal failure — claim under guarantee
Difficult to open/close	Adjustment needed — contact installer
Colour fading (uPVC)	Choose quality foiled frames with UV protection
Paying too much	Always get 3+ quotes and never sign on the day