A-rated double glazing in London typically costs £500 to £1,200 per window in uPVC and £900 to £2,000 in aluminium, fitted. A 3 bed house with 8 to 10 windows usually lands between £5,000 and £12,000, and a composite front door adds £1,200 to £2,500. Those are indicative market ranges, not a quote; the size, style and opening arrangement of each window moves the price more than anything else.
Key takeaways
- uPVC double glazing: typically £500 to £1,200 per window installed. Aluminium: £900 to £2,000.
- Whole house, 3 bed with 8 to 10 windows: typically £5,000 to £12,000 for uPVC.
- Composite front door: £1,200 to £2,500 fitted.
- Windows and doors are 20% VAT; they are not on the 0% energy-saving materials list.
- Every replacement window needs a FENSA or CERTASS certificate. Keep it; you need it when you sell.
- Windows are 10 to 20% of a home's heat loss. Insulating walls and roof usually saves more per pound.
How much does double glazing cost per window?
The per window price depends first on the frame material, then on size, then on how many opening sashes it has. A fixed pane is the cheapest window you can buy; every opener adds hinges, locks and a sash frame. The ranges below are for A-rated double glazed units installed in a London home, including removing the old window and making good the inside reveal.
| Frame material | Indicative cost per window | Notes |
|---|---|---|
| uPVC, white | £500 to £1,200 | The standard choice; lowest cost, low maintenance |
| uPVC, coloured or woodgrain foil | Upper part of the uPVC range and above | Anthracite, black and woodgrain finishes cost more than white |
| Aluminium | £900 to £2,000 | Slim frames, larger panes, powder coated in any colour |
| Timber | Quoted per window | Usually the dearest option; often required in conservation areas |
| Bay window (3 to 5 panes) | Quoted as one unit | Structural support and a new bay roof or pole can add to the cost |
Small top hung bathroom windows sit at the bottom of the range. Large living room windows with two side openers, or a bay, sit at the top or above it. If a quote is far below £500 a window, ask what glass, what frame and what guarantee you are getting.
What does it cost to double glaze a whole house?
Most people replace all the windows at once because the scaffold, the disruption and the survey are shared. The figures below are worked from the per window ranges above for uPVC; aluminium is roughly double at the top end.
| Home | Typical window count | Indicative uPVC total |
|---|---|---|
| 1 or 2 bed flat | 4 to 6 | £2,000 to £7,000 |
| 2 bed terrace | 6 to 8 | £3,000 to £9,500 |
| 3 bed semi or terrace | 8 to 10 | £5,000 to £12,000 |
| 4 bed detached | 12 to 15 | £6,000 to £18,000 |
The 3 bed figure is the one most often quoted in the market and it is the one to sanity check other quotes against. Flats can be more complicated than the count suggests: upper floors may need a scaffold or a hoist, and leasehold flats usually need the freeholder's consent, especially where the windows count as part of the building structure.
How much do new doors cost?
A composite front door, which is a foam filled slab with a glass reinforced plastic skin in a uPVC or timber frame, typically costs £1,200 to £2,500 fitted, depending on the glazing, the side panels and the hardware. Composite doors have replaced uPVC as the default because they look like timber and hold their shape.
French doors, patio sliders and bifolds are priced per opening and vary widely with width, material and the number of leaves. Get them itemised on the same quote as the windows so the installer treats the whole elevation as one job.
What pushes the price up?
- More openers. Each opening sash adds hardware. Fixed panes with one opener per room are the economical layout.
- Colour and finish. White uPVC is the base price. Foils, dual colour (white inside, dark outside) and powder coated aluminium all add to it.
- Style details. Georgian bars, astragal bars, arched heads, leaded glass and sash horns are extras.
- Glass upgrades. Acoustic laminated glass for road noise, obscure glass, toughened glass where required near floors and doors, and triple glazing. See double vs triple glazing.
- Access. Upper floor windows on a flat or a tall house may need a scaffold or tower.
- Structural work. Rotten lintels, bay poles and enlarging or moving an opening are building work priced separately.
- Making good. Plaster repairs to reveals, new internal sills and redecoration. A good installer includes basic making good; check that it is listed.
- Conservation areas and listed buildings. Timber frames, slimline units or a planning application can all be required. See insulating a period or listed home.
Do I pay VAT on double glazing, and what is FENSA?
Windows and doors are charged at 20% VAT. They are not on HMRC's list of energy-saving materials, so they do not get the 0% rate that applies to insulation, solar panels, batteries and heat pumps until 31 March 2027. All the prices on this page assume 20% VAT is included. If you are combining windows with wall insulation, the two are split on the quote at their own rates; see the 0% VAT guide.
Replacement windows and doors are controlled work under Building Regulations in England. The installer must either be registered with a competent person scheme, FENSA or CERTASS being the two you will see, or the work must be signed off by building control. A registered installer issues a certificate after the job and notifies your council. You will be asked for that certificate when you sell the house, so keep it with the deeds.
Are new windows the best use of the money?
Often not the first use. Windows are usually 10 to 20% of a home's heat loss. Solid walls, an uninsulated loft and a suspended timber floor lose more, and are cheaper per unit of heat saved. A loft top-up is £400 to £900; a whole house of windows is £5,000 to £12,000. See where homes lose heat and the insulation cost guide.
The right time for new windows is when the old ones are failing: misted units, rotten frames, draughts you can feel, or noise. If you are also insulating the walls, plan the two together. External wall insulation changes the depth of the reveal, and windows fitted before or after without that in mind end up with cold edges and awkward sills. Our guide to window reveals and sills explains the detail. A free heat loss survey will put windows in order alongside everything else.
Frequently asked questions
How much does double glazing cost for a 3 bed house?
Indicatively £5,000 to £12,000 for 8 to 10 uPVC windows, fitted and including 20% VAT. Aluminium frames, coloured finishes, bays and extra openers push it towards or beyond the top of that range.
How much is one double glazed window?
Typically £500 to £1,200 for a uPVC window and £900 to £2,000 for aluminium, installed. Small fixed or single opener windows are at the bottom, large multi-opener windows and bays at the top.
How much does a composite front door cost?
Typically £1,200 to £2,500 fitted, depending on glazing, side panels and hardware.
Is double glazing 0% VAT?
No. Windows and doors are 20% VAT. The 0% rate until 31 March 2027 applies to energy-saving materials such as insulation, solar panels, batteries and heat pumps, not glazing.
Do I need a FENSA certificate for new windows?
Replacement windows are controlled work under Building Regulations. A FENSA or CERTASS registered installer self-certifies the work and issues a certificate; otherwise the job has to be signed off by building control. Buyers' solicitors ask for the certificate, so keep it.
Is there a grant for double glazing?
Not for most homeowners. Councils fund energy measures for low income households through the Warm Homes: Local Grant until March 2028, with the council choosing the installer, and windows are not usually the priority measure. For everyone else there is no grant and no VAT relief on windows.
Should I insulate the walls or replace the windows first?
Usually the walls, unless the windows are failing. Walls lose more heat than windows and insulation is 0% VAT. If both are planned, do them as one project so the reveals and sills are detailed properly.