How much does double glazing cost?

How much does double glazing cost?

Discover all the different factors that can affect how much double glazing costs, so you can consider what would be the best option for you.

How much does double glazing cost

How much does double glazing cost?

When researching double glazing costs there are many variables to consider.

Plenty of websites offer lists of prices of double glazed windows, but these are usually the cost for a basic off-the-shelf window and without the cost of installation. We can't stress enough the pitfalls of buying cheap double glazing.

For an accurate cost to install double glazing in a house requires a survey from a double glazing installer. Taking into consideration any complications to fitting your windows and advise on the best style of window for your property.

As a rough guide, we've put together a range of average double glazing starting from prices below (but, the cost to double glaze your house could be considerably different).

The cost of double glazing is anything between £600 to £3,600 per window, depending on options.

MaterialAverage cost for new double glazing
uPVC casement window£600 - £1,800 per window
Sash window50% more than a casement window
Tilt and turn window25% more than a casement window
Bay window150% more than a casement window
Aluminium frame25% more than uPVC
Timber frame50% more than uPVC

Is it worth getting double glazing?

Double glazed windows are the most popular choice of windows for homeowners in the UK and the benefits are well proven:

  • The weather has a lot to answer for here in the UK and for this reason, being more energy efficient is necessary to keep us dry and warm. A+ double glazing can save up to an average of £145 a year on energy bills.
  • Double glazing can make our homes healthier environments as it reduces the build-up of condensation on windows and the growth of black mould.
  • If you live in a noisy area, noise reducing double glazing can significantly reduce the background noise and help you get a better night of sleep.
  • What really makes double glazing worth it is the increase in property value you can expect and the long-term payback of reduced maintenance costs.

Types of window styles

Types of window styles

How the window frame style affects the average cost of double glazing

Casement windows

This is the standard style of window that has been fitted in the UK for hundreds of years. Casement windows open on a side hinge with either one pane opening or a pair.

The average cost of double glazing for a white uPVC casement window ranges between £600 to 1,800 depending on size, glazing design and how many are being replaced in the property.

Sash windows

A beautiful and aesthetically pleasing window that can add significant value to a house. A sash window has two framed panels that slide up and down over each other.

Most often fitted in period properties and around London, many listed buildings are required to have sash windows.

The cost to double glaze a sash window is usually 50% more than a casement window.

Tilt and turn windows

The Tilt and turn window has become a hugely popular style for uPVC and aluminium windows because they can be securely left open for ventilation by tilting them inwards whilst remaining fully locked.

The cost of double glazed tilt and turn windows is usually 25% more than a casement window.

Bay windows

Bay windows extend out from the room and because of this, you require three windows instead of one.

Great for letting in lots of light and giving extra space in your living space a bay window gives you panoramic views from your house.

The cost of a double glazed bay window can be up to 150% more than a casement window.

Types of window material

How the window material affects the average cost of double glazing

Apart from the style of a window, the material for the frame used also impacts on the average cost of double glazing:

uPVC windows

Unplasticised Poly Vinyl Chloride, otherwise known as uPVC, has been one of the most popular choices for double glazed windows in the UK since the eighties.

uPVC double glazing is thermally efficient, low maintenance and secure. It's also the most economical material for windows.

The average cost of double glazing for uPVC casement windows is between £600 to 1,800 depending on size, glazing design and how many are being replaced in the property.

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Aluminium windows

Another easy to maintain window frame choice that's popular for it's slimline appearance.

Aluminium isn't as thermally efficient as uPVC but does offer a contemporary look and most often used in modern properties.

The cost of double glazed aluminium windows is 25% more than uPVC but 25% less than timber frames.

Timber windows

Nothing beats the look of well-maintained wooden window frames. A quality hardwood window is a good investment for a home and can add significant value, especially in period properties.

The oldest material choice of windows, timber frames can last for years if they are well looked after, but they are high maintenance and need a lot of attention.

The average cost of wooden double glazing windows is 25% more than aluminium and 50% more than uPVC.

Other options that affect how much double glazing costs

Apart from the style and material of a double glazed window, there are other factors that will impact on the cost of new double glazed windows.

Size - it might seem obvious but a large living room picture window is going to cost significantly more than a small toilet window.

This is the main reason why it's so difficult to answer the question of how much does double glazing cost.

Energy rating/quality of glass - glass might look all the same but there is a huge difference between the quality of energy efficiency performance.

When buying new double glazing look at the thermal efficiency, the solar gain and the air leakage values. A window rated A++ is the highest rated across all of the above and should be what you choose to make the investment in double glazing worth it.

Furniture and finish - door handles, locks, number of opening windows, colour and any grain effects all need to be factored into the double glazing cost.

Cheap windows might not include extras and you will need to pay more for upgrades to get the handle or locks that you want. Don't underestimate how much the finishing touches can add to a basic price.

What should your quote for double glazing include?

If you're comparing the average cost of double glazing from different companies and want to know how much does double glazing cost, make sure you are comparing like-for-like.

As we highlighted above, there are many variables to consider that can dramatically alter a price. Even factors like installing in an upper floor that would require scaffolding have to be taken into account.

If you do want to compare quotes then make sure your double glazing cost quote has the following:

  • A full technical survey with drawings
  • Full product details of size, style, colour etc.
  • The number of windows
  • The window energy rating (WER) for the glass
  • Any additional features, such as handles and locks
  • Does it include external window sills?
  • When does the work start and finish?
  • Disposal of your old windows
  • Warranties for installation
  • Guarantees for products
  • Company details and accreditations (see below)

What double glazing accreditations and standards should I look for?

Building regulations do apply to double glazing window replacement so you must use a reputable company that is registered under the competent person scheme. They give you a certificate of completion that states your windows pass regulation otherwise you have to obtain build regulations permission yourself (at additional expense).

The accreditations to look out for include:

  • Competent person scheme CERTASS
  • Fenestration Self Assessment Scheme FENSA
  • British Standard Institute BSI
  • The Glass and Glazing Federation GGF
  • Secured by Design, the official police security initiative SBD

You can read about Everest accreditations here and an explanation of CERTASS here.


  • +
    How much is double glazing for a 3-bed house?

    When budgeting the double glazing cost for a 3-bed house you will need a price for how many windows there are.

    An average 3-bed semi-detached house has 3-4 windows at the front and back = 8 windows.

    An average small detached house has 4 windows front and back and 2 on the side = 10 windows.

  • +
    How long does double glazing last?

    Double glazing lasts for around 20 years but does vary depending on the quality of the window units and the quality of the installation.

    Reputable double glazing manufacturers and installers will offer guarantees (at Everest, we offer a standard 10-year guarantee on all windows and lifetime guarantees against internal condensation and discolouration*).

    Of course, windows can last far longer than their predicted lifetime and many houses have windows that are over thirty years old - if they've been well-maintained.

    The first part of the double glazed window that is likely to fail is the seal and second to that are the hinges.

    It also depends on where the windows are positioned in a property. For example, a south-facing window that gets a lot of sun and heat is more prone to discolouring or the seals drying out.

  • +
    Does double glazing increase the property value?

    House buyers in the UK rate double glazing and central heating at the top of their list when looking for a new home.

    Double glazing can increase the property value by up to 10% if the windows are of good quality and the style and colour are in keeping with the property. Therefore, an investment in new windows can pay back if you are thinking of selling.

    Beware though, the windows must suit the property and if you get this wrong you can decrease instead of increasing the value. For example, period properties suit timber frames and traditional sash windows. If you remove old sash windows to replace with uPVC double glazing you can devalue the house.

  • +
    Cheap double glazing windows or quality double glazing?

    Don't ever be fooled into thinking that cheap double glazing is a better option than paying more to install quality windows.

    As we highlighted above, fitting uPVC in a period property instead of timber can decrease the property value and turn off buyers.

    Poor quality double glazing can have a host of issues and you may also find that a cheap supplier has a cheap or non-existent guarantee. More importantly, only reputable well-established companies can offer a lifetime guarantee with the confidence they will be there in twenty years to replace a window if there is a problem.

    Cheap window companies are more likely to not be around to honour warranties when you need them.

    For any investment, you make in your home, quality should always take precedence over price. Trying to do anything on the cheap always turns out to be expensive in the long-term.

  • +
    Double glazing or triple glazing?

    Just when you got used to buying double glazed windows, along came triple glazed to throw another option into the equation.

    The benefits of triple glazed are:

    • Thermal efficiency - an extra pane of glass with more argon gas sandwiched between boosts the A+ rating to A++ and the highest rating a window can have. The result is a reduction in energy bills and a warmer house.
    • Soundproofing - acoustic glass can reduce sound by 40 dB and make a road seem four times further away.
    • Security - one more pane of glass to get through makes a window with serious resistance.

    The cost of triple glazing is 10-20% more than double glazing, but you can gain 20-30% more energy efficiency.

  • +
    What is the cost of secondary double glazing?

    As an alternative to double glazing, secondary glazing might be a more economical option to consider.

    Instead of replacing the full window, secondary glazing fits internally over your window recess to give a second layer of insulation over the window.

    Why would you choose secondary glazing over double glazing?

    • If you live in a period property or have a clause in your lease that stops you from replacing your single-glazed (usually sash) windows.
    • You want to retain the style of your original windows.
    • You want to eliminate draughts without the expense of new windows.
    • You want to reduce the noise if you live next to a busy road.
    • Secondary glazing is great for acoustics and can reduce external noise pollution by up to 80%.

    The cost of secondary glazing can be up to 50% less than installing double glazing new windows.

When should I replace my double glazing?

Replacing a full house of 8-10 double glazed windows is an investment that will cost several thousand pounds and is a big decision for most people.

We would never recommend for you to replace windows that are in perfectly good condition without any issues. However, it does get to a point when your windows are letting the property down and you would be far better to take the investment.

  • Draughts - the main reason to change windows is that your old ones are letting in considerable draughts and cold which can seriously push up your energy bills. Double glazing seals can fail so if you can feel cold blowing around the edge of the window it might be time to change them. Or, your original windows may have been badly fitted with lots of expanding foam around the edges to make up for a poor fit. If this is the case, we would recommend replacing.
  • Warped frames - older cheap uPVC can warp and discolour leaving windows that look tired and shabby. Warped windows can also cause issues with gaps around the edges letting in cold air. If your white windows are now the colour of sour cream then it could be time to upgrade.
  • Condensation - if you have condensation inside the double glazing it indicates the seals on the windows have failed. If you have this problem the only real way to solve it is to replace the windows. Check with your installer or manufacturer as they might be covered under warranty.
  • Desiccant - this is where you have bits inside the glass caused by the seals failing.
    As with condensation, the only way to solve this permanently is to replace the units with failed seals. Again, check your warranty and guarantee.

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