The Cost to Fit Double Glazed Windows

All you need to know about the installation costs of double glazed windows including materials, labour and time frames.

Double Glazed Window

What the job entails

This article is all about double glazing and the costs you might expect to pay in the UK. Benefits of energy-efficient double glazed windows include reduced energy bills and a smaller carbon footprint. A more comfortable home thanks to reduced heat loss through windows and fewer draughts or cold spots. Reduced noise levels so more peace and quiet. Once double glazing has been fitted you will also experience less condensation build-up on the inside of windows. The costs and potential savings for double glazing will of course vary for each home and even each window, but when calculating the savings on energy and return on investment, you can expect the double glazing to last for 20 years or more. Despite the promises made by double glazing salesmen, an investment in double glazing will not pay off in terms of recouping the money spent in energy bill savings for many years, decades even! But double glazing does offer a much more comfortable and secure home, plus it will make it easier to sell if that is an issue.

Double glazed windows have two sheets of glass with a gap in between which creates an insulating barrier to keep the heat in. This gap is sometimes filled with gas which makes the windows even more energy-efficient but will also increase the overall cost. Double glazed windows come in a range of materials, styles and performance rating which is defined by how well they stop heat from escaping through the window. Some windows are also rated by how effectively they block sunlight and reduce noise.

The double glazing window industry in the UK has a terrible reputation, particularly for aggressive sales tactics and cold calling, but the fitters and installations themselves also come in for a fair amount of criticism. Many double glazing companies will use high pressure sales tactics involving a very long visit to your property lasting several hours. The most common high pressure closing tactic is to initially offer a very high price but then offer a huge discount for any number of invented reasons, but always involving you agreeing to sign the sales contract right there and then without taking any time to consider it or compare with other quotes. This dodgy sales tactic often involves the salesman phoning the head office as the "discount" is so amazing he can’t authorize it without permission! It's all complete nonsense of course starting with a grossly inflated price and a false discount.

You will in fact get the very same - if not better - deal the next day or the next week, so no need to sign anything straightaway! Ignore all these hard sell tactics and just get a written quote that you can compare to other companies and think about it for a few days or weeks. Make it 100% clear you will be comparing with other quotes and not making an instant decision. To try and avoid the worst excesses of the industry, choose a double glazing company that is a member of a reputable trade body such as Fensa or Certass. Fensa is part of the government authorised Competent Persons Scheme for the replacement of windows, whereas Certass is a UKAS approved body. Note that a 10/20/30 year warranty offered by a company that will likely not exist next year is not worth the paper it is printed on! Stick to reputable companies with a good track record, trade body membership and insurance backed guarantees.

There is much to go wrong when fitting double glazing, this is not recommended as a DIY job and it is important you use competent and experienced fitters. Even the very best quality double glazing can be ruined by a poor quality installation. Poor installation can cause all sorts of problems, but the most obvious ones initially are condensation problems between the panes, draughts due to the seals around the windows not being correctly installed, and leaking during bad weather. Never pay for double glazing installation fully in advance, paying a small deposit is standard practice, but don't part with the balance until the job is completed to your satisfaction.

Remember that double glazing quotes do not normally include any special or unusual requirements unless specifically stated. Features such as coloured Upvc Frames, "A" Energy Rated Windows that are more efficient at retaining heat, lead framed glass, triple locking security mechanisms, and triple glazed windows – all add cost to any installation. If your home is higher than 2 stories you should also expect to pay more.

Also, whilst you're getting double glazing installed you might want to consider installing a velux window in your loft or even a skylight on a flat roof. You could get them priced in the quote at the same time which would save you a lot of money if you were already planning to do it later in the future.

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The Cost to Fit Double Glazed Windows

The average cost to fit double glazed windows is typically around £3000 to £4000 for an average semi-detached house with eight windows and two doors. The average price varies depending on location, the amount of windows, quality of glass, amount of openings, type of window locks, and any scaffolding costs required.

Most window specialists work in pairs and charge around £300 per day in total for labour. The overall time to complete the job will take around two days, as a team of two on average are able to install up to 6 windows a day depending on the ease of access.

Below are some estimated costs of installing double glazed windows:

Number of Windows Avg. Cost Duration
8 windows with 2 uPVC doors £3000 - £4000 2-3 days
15 windows with 2 uPVC doors £5000 - £6000 3-4 days
20 windows with 2 uPVC doors £6000 - £7000 4-5 days

Cost Breakdown

Individual costs for installing 8 double glazed windows and 2 uPVC doors for a semi-detached home - Total Cost: £4000






Waste Removal


A team of two would normally be able to install up to 6 windows per day, so in a typical 3 bed semi-detached home, it would probably take around 2 days to replace all windows and doors. This obviously assumes no access problems requiring scaffold or access towers and assumes a completely standard installation.
Plants, pets and people increase the amount of moisture in a room, the average person will breathe out around 2 litres of moisture per night and this moisture has to go somewhere, if it cannot escape it will condense on cold surfaces, such as traditional windows which are not double glazed. It is important to ensure adequate ventilation to allow the warm moisture filled air to escape. This is why most double glazed windows will have trickle vents across the top of the windows, but you need to then keep them open!

Fitting energy rated double glazing will reduce the amount of condensation forming on the windows and reduce cold bridging. UPVC double glazed windows use internal chambers in the glass units to keep the inside surface temperature of the product higher, thus reducing condensation. If you get double glazed windows fitted and still suffer from condensation on the window panes, then either the double glazing is faulty, the room is too cold, or there is insufficient ventilation in the room.
For a typical UK semi-detached house with 8 windows and two doors (one of which being a patio sliding door), all done in white Upvc with a frosted bathroom window and no special requirements or access problems. Expect to pay around £4000-£5000.