Double Glazing Cost Guide 2021

When it comes to windows, you’re probably familiar with the term ‘double glazing’. Simply put, double glazed windows consist of two panes of glass put together with a gap between them. The barrier prevents heat from radiating out of the home when its cold. This traps an insulating barrier of air inside, making the home much more heating efficient.

These days double glazed windows come pre-installed on most new homes. But a lot of older properties either have single glazed windows or, after years, damaged double glazing that needs replacing.

However, as soon as you start looking into getting replacements, you’ll likely find yourself bombarded with various types of window, sizes, makes, manufacturers and – most importantly – prices. All of this can be overwhelming, especially if you’re new to homeowning.

In order to streamline and demystify this process, Quotatis have put together this comprehensive 2024 guide to double glazing. This article covers every aspect of why you might need double glazing, the options available to you, the financial implications and a variety of other things. If you think we’ve missed anything, tweet us @Quotatis and let us know.


  1. General advice
  2. Why do I need double glazing?
  3. Are there problems with double glazing?
  4. What kinds of double glazed windows are there?
  5. How much does double glazing cost?
  6. When should I replace my double glazing?
  7. How much does it cost to replace double glazed windows?
  8. When should I replace my double glazing?
  9. What accessories are there for double glazed windows?
  10. Alternatives to double glazing
  11. Other uses of double glazing
  12. Who can install double glazing?
  13. Things to look out for

General advice

Set a budget

Try and set a realistic budget for your double glazing project before getting quotes. That way, you can easily compare quotes against your budget and know exactly what you can afford.

Do your research

Make sure you understand what type of window you’re looking for. Prices can vary hugely depending on the type of glass and frame. Always try to compare similar windows, so you know which quote offers the best price.

This double glazing price guide covers everything you need to know before making a purchase. But if you’d like to investigate any particular topic covered by the guide in greater detail, Quotatis has plenty of other posts exploring countless aspects of double glazing, home renovation and energy efficiency within the home. Find them here.

Think about the savings

double glazing money savings

Replacing your double glazing with more energy-efficient windows will save you money on your heating bills. Take this into account when getting quotes, as more efficient glass will cost more but also save you more money.

So, if you’re thinking of moving within the next year it may not be the best idea. But if you don’t plan on moving then double glazing could be a wise investment.

Why do I need double glazing?

Weather protection

Double glazing, like any window, will shield against strong winds, heavy rain and snow. The added benefit is that the increased thickness of double glazing, alongside its heat insulation, mean that during bad weather you’re less likely to feel the cold drifting into the house.

Heat insulation

Installing double glazing can retain an extra 8-12% of the household heating. This increases your thermal efficiency, meaning you’ll need to use your central heating less to achieve the same results. It’s also useful if you live in cold areas or if autumn and winter are quickly approaching.

Energy efficiency

double glazing energy savings

The other benefit of increased thermal efficiency is that if you use less heating you spend less money. For reference, all windows are given an energy performance rating between A++ to G (from best to worst). When purchasing new double glazing, the lowest grade a professional can install without breaking the government building regulations is a C rating.

Higher graded windows obviously save the most money per year, but they come at an increased price with every grade they rise through. Still, given the savings and the reduced environmental impact of using less heating, A grade double glazing is smart investing.


Newly fitted windows obviously don’t suffer from the adverse effects of age or wear and tear. This means that they add an extra level of security to the home. The second pane in double glazing also makes it harder to break into. Any intruders would have to smash through twice the glass, which is a handy preventative measure.

New windows also enable you to build in the newest, and therefore hardest to crack, lock. Bear in mind that the more extravagant the locking mechanism the higher the cost. Always make sure to weigh up how vital additions like this are to the installation.

Something else worth noting: many insurance companies will reduce their premiums if you can provide proof that the windows you have are new double glazing. As such, double glazed windows can save money in multiple areas.


The natural lifespan of double glazing clocks in at around 20-25 years depending on the make and manufacturer. This is such a long period of time that the windows could likely pay for themselves through heating bill savings alone. Security benefits and weather protection become added value.

Are there problems with double glazing?

It’s worth pointing out that while double glazing has many benefits, it can also be a costly procedure to renovate your home with it. If you’re replacing one or two windows, the overall cost will be quite low. However, installing it across a whole house can become extremely expensive. Double glazing prices vary widely across brands and sizes.

Depending on the size of your home, a top-to-bottom renovation can cost thousands of pounds – plus labour costs! This is all to say that while double glazing has many perks, you need to make sure you’re in a financial position where the upfront costs make sense for you.

What kinds of double glazed windows are there?

There is an incredibly wide array of double glazing styles, each with their own strengths, weaknesses and price ranges. Below is a list of the most common double glazed window types with a breakdown of what they offer.

uPVC white casement

One of the countries most popular options, uPVC comes with an affordable price and a simple, stylish appearance that makes it a good fit for nearly any home. They’re hinge-based and can be installed to open either inwards or outwards. You can also request that the professional that’s installing your window does so in one of any of these formats:

  • Centre-hinged
  • Bottom-rung
  • Top-hung/awning
  • Top light casement
  • Side hung casement
  • Sliding folding casement

French uPVC white casement

Still a white casement, but with a much wider opening. Unlike regular casement, there’s no supportive beam running through the middle of it. This allows both sides to be fully opened, inward or outward – this creates the clearest views out of your window and maximum room for air flow in the hot summer months.

French uPVC is more expensive than its regular counterpart, however. It can potentially be up to or even above 50% more in cost.

Bay windows

double glazing bay windows

Bay windows sacrifice cheapness for aesthetic and space. They are an elegant addition, often used at the front of homes to evoke the class of certain 19th century designs. Bay windows are installed in sets of between three and five.

Two windows are installed extending out from the home, with each successive window angling more inward as they’re set up. The result is something of an arc shape that fans out from the home and creates more space, which is ideal for a living room.

Bow windows

Bow windows are like bay windows, only they are made up of a much larger set of panes, often going up to eight windows altogether. The larger number of double glazed windows means the shift in angles between each is much more subtle, creating a more curved visual design than the bay window’s angular one.

Sash windows

Sash windows are divided in two lengthways, allowing you to slide the bottom half up to allow air in/out. They have a traditional, clean look that maximises functionality. Most sash windows are found on period buildings.

On average, sash windows will be priced at twice the price of uPVC white casement, and up to 30% more than French uPVC white casement.

Tilt/turn windows

An increasingly popular choice, tilt/turn windows are both stylish and highly functional. They have a unique operating method, with handles at the top and sides of the frame. Using the top handle tilts it in or out via the hinges at the bottom. Using the side handles causes it to operate as though it were a casement window. This level of flexibility is great if you really want to control how much air flows into your home and how much heat you let out.

Tilt/turn windows also tend to require very little in terms of repairs and upkeep. Rigorously high standards are maintained throughout their manufacturing process. Installing this type of window could be a good choice if you want to save time and money on maintenance down the line.

At a premium of 45% more than regular casement double glazing, but still less than French uPVC, tilt/turn windows come in at a moderate price range.

How much does double glazing cost?

In this section Quotatis have compiled price lists for the multiple types of double glazing explained above. These prices come in price bands, to account for the variance between brands.

Regular uPVC casement windows 

Window size Frame Average price
500mm x 500mm Wood £150 – £175
500mm x 500mm White £138 – £162
1000mm x 1000mm Wood £216 – £246
1000mm x 1000mm White £199 – £232
1200mm x 1200mm Wood £257 – £301
1200mm x 1200mm White £238 – £267

(The above prices are based on double glazed windows without an opener. You can opt to add an opener during the purchasing stage. If you do, the additional cost per window will range from an extra £40-£60 depending on the frame size.)

French uPVC casement windows 

Window size Frame Average price
500mm x 500mm Wood £575 – £628
500mm x 500mm White £446 – £502
1000mm x 1000mm Wood £621 – £675
1000mm x 1000mm White £498 – £550
1200mm x 1200mm Wood £669 – £726
1200mm x 1200mm White £518 – £576

Sash windows 

Window size Frame Average price
500mm x 500mm Wood £624 -£706
500mm x 500mm White £522 – £601
1000mm x 1000mm Wood £725 – £828
1000mm x 1000mm White £617 – £737
1200mm x 1200mm Wood £841 – £952
1200mm x 1200mm White £724 – £839

Tilt/turn windows 

Window size Frame Average price
800mm x 800mm Wood £523 – £575
800mm x 800mm White £399 – £454
1000mm x 1000mm Wood £569 – £626
1000mm x 1000mm White £476 – £540
1200mm x 1200mm Wood £615 – £691
1200mm x  1200mm White £498 – £550

Bay windows

Given the variable, multi window nature of bay and bow windows, both types have been listed with three tables instead of one. These tables should give you an strong indication of how much a 3-, 4- and 5-set of bay or bow windows would cost, and how that changes with casement size.

Bay windows (3 pane set)

Window size Frame Average price
2400mm x 1200mm Wood £1145 – £1260
2400mm x 1200mm White £1048 – £1151
3000mm x 1200mm Wood £1270 – £1384
3000mm x 1200mm White £1147 – £1256
3000mm x 1500mm Wood £1368 – £1475
3000mm x 1500mm White £1252 – £1370

Bay windows (4 pane set)

Window size Frame Average price
3000mm x 1200mm Wood £1524 – £1628
3000mm x 1200mm White £1400 – £1515
3000mm x 1500mm Wood £1645 – £1752
3000mm x 1500mm White £1499 – £1612
3600mm x 1500mm Wood £1753 – £1917
3600mm x 1500mm White £1606 – £1700

Bay windows (5 pane set)

Window size Frame Average price
3600mm x 1200mm Wood £1905 – £2065
3600mm x 1200mm White £1842 -£2009
4000mm x 1200mm Wood £2018 – £2150
4000mm x 1200mm White £1910 – £2078
4000mm x 1500mm Wood £2156 – £2310
4000mm x 1500mm White £2060 – £2212

Bow windows

Bow windows (3 pane set)

Window size Frame Average price
2400mm x 1200mm Wood £1150 – £1260
2400mm x 1200mm White £1045 – £1155
3000mm x 1200mm Wood £1286 – £1390
3000mm x 1200mm White £1162 – £1271
3000mm x 1500mm Wood £1380 – £1492
3000mm x 1500mm White £1254 – £1352

Bow windows (4 pane set)

Window size Frame Average price
3000mm x 1200mm Wood £1532 – £1641
3000mm x 1200mm White £1404 – £1515
3000mm x 1500mm Wood £1660 – £1780
3000mm x 1500mm White £1500 – £1603
3600mm x 1500mm Wood £1752 – £1908
3600mm x 1500mm White £1604 – £1700

Bow windows (5 pane set)

Window size Frame Average price
3600mm x 1200mm Wood £1842 – £2003
3600mm x 1200mm White £1903 – £2070
4000mm x 1200mm Wood £2020 – £2165
4000mm x 1200mm White £1902 – £2053
4000mm x 1500mm Wood £2150 – £2330
4000mm x 1500mm White £2068 – £2222

How much does it cost to replace double glazed windows?

man in white hard hat fitting aluminium window

In the short term, it may make more sense to repair faulty double glazed windows rather than replace them. This is due to the lower price involved. However, if the problem is recurring, or if the windows have been installed for a very long time, this might not be the saving it seems. There’s a high likelihood you’ll have to repair them again soon. Alternatively, you may have to buy new double glazing when your current units reach their natural end anyway.

In these cases, you need to consider the cost of replacement. It’s difficult to give an exact figure but you should anticipate costs around £150-£500 per window. Again, size, brand and materials all affect price, as does the incorporation of extra decorative elements.

When should I replace my double glazing?

As double glazing units have a lifespan of up to 25 years, but will likely suffer wear and tear and/or weather damage, you may want to consider replacing your existing windows once they get to around 18-20 years old. Of course, if you have serious problems before this time then check your warranty and see if you’re still covered. If not, check the next section for how much replacing double glazing could cost.


Unless your double glazing has obvious, visible damage (such as a large crack running down a pane, or mould), then replacing it for cosmetic reasons is unnecessary. In most cases, any visual degradation can be fixed with some regular cleaning, or at most the intervention of a professional window cleaner.

In the case of mould growing anywhere on, in or near the windows though, replacing them might be a better option. You could pay to have them fixed, but de-moulding can be expensive when professionally carried out. Also, if any mould is missed then the whole process will have to be repeated when it regrows.

Furthermore, if your double glazing is framed in wood then eventually damp will set in and the window fixture will start to rot. If left untreated, this can cause you to lose more and more heat as its condition worsens, let alone create a safety hazard. Use this as an opportunity (if feasible) to fully replace the wooden frame with a whole new material.

Difficulty of use

At a certain point, your windows are likely to become stiff and difficult to operate. This means the hinges will be degrading to the point of irreparable damage. Not even a generous amount of oil will loosen them up for a sustained period.

As the hinges become more unusable, they present not just an inconvenience but a security risk. The more damaged the hinges become the easier it’ll be for intruders to take advantage and break in.



Does it feel like your house is colder than it usually is? Has your heating bill risen higher and faster than you’ve expected? These are all signs that the structural integrity of your windows could faltering and that they need replacing. A tell-tale indicator that this is true is if these signs are coupled with increased condensation inside the panes.


Should you have any items of furniture that lie within direct sunlight let in by a double glazed window, you may notice odd occurrences. The longer double glazing is installed for the more it eventually lets in UV rays that it previously had blocked. The effects of this include discolouration or “sun bleaching” on your sofas, chairs, carpets and more.

What accessories are there for double glazed windows?

As you’d expect, double glazed windows increase in price when you add accessories to them. Here’s a list of possible accessories that you could add to your windows and frames:

  • A design applied to the glass pane itself
  • Metallic handles, such as stainless steel, chrome, or gold
  • Specific finishes applied to the frame (for example, a wood finish)
  • Toughened, frosted or self-cleaning glass
  • Different coloured frames, such as black, grey or dark green

Alternatives to double glazing

There are very few reasons why installing double glazing in a home wouldn’t be possible or appropriate, but they do exist. A couple of potential reasons you might be prevented from installing it is if the building you’re renovating is either a listed property or part of a conservation area. These types of residences may be subject to specific rules and guidelines that prevent you from altering the windows. Make sure to check this beforehand!

On the other hand, double glazing may be insufficient if you live in an extremely noisy area, such as by a main road or near an airport.

In these cases, it may be worth researching secondary glazing and/or triple glazing.

Secondary Glazing

This is where an additional layer of glass is added inside a window you already have and is, on average, cheaper than double glazing. The downside is that, while it can save you some money in the upfront costs, its insulation properties are weaker. Therefore, its energy efficiency is lower and you save less money than you would with double glazing. That said of course, it’s still more efficient than single glazed.

On top of that, the noise prevention of secondary glazing is less than that of its double glazed counterpart, but again, better than single glazing.

If your property belongs to a conservation area, then it is likely that it already has secondary glazed windows. This is because the process of adding secondary glazing allows the original windows to be retained. As a result, the cultural significance and/or heritage of the location can be kept intact.

Triple Glazing

On one hand, triple glazing is more expensive than double glazing, and for most homeowners is usually an unnecessary expense.

On the other hand, triple glazing is much more effective. It creates two air barriers between the glass panes, further improving from the heat efficiency of double glazing. It’s also thicker, which makes it harder to break through, thereby making your home more secure. And, as expected, it reduces outside noise to an even greater degree.

If you live in an area that is disproportionately affected by cold weather, or live nearby a noisy main road, then triple glazing could be a viable alternative to double glazing.

Other uses of double glazing in the home

Double glazed doors

You may find that your home has space to introduce double glazing to either glass panes on your front door. In some cases, you may even have sliding French doors that are almost entirely glass with plastic frames.

If you decide you want to add double glazing to either of these types of door for any of the same reasons as you would install it on windows, then you’ll find that the factors affecting its price are much the same too. The non-glass materials used will greatly affect price – with uPVC being cheaper and aluminium more expensive.

Additionally, the type of door will affect this too. Front and patio doors will be at a comparable price level across brands, with French and bifold doors on a level above that.

Should you be interested in adding any of these to your home, fill in the form at the bottom of the page. Quotatis will get back to you with up to four tradesmen that can give you a reasonable quote.

Who can install double glazing?

Unlike how tradesmen and companies need an accreditation from the Gas Safe Register in order to install boilers, there are no similar required qualifications for fitting double glazing. In fact, you could very well buy the windows straight from a supply and install them yourself.

We recommend hiring a local, reliable tradesman, not only because of their experience but if there are any issues post-installation then you have someone you can call for support. While you can save a little bit of money, the potential risks, time investment and peace of mind of a professional installation comes with are irreplaceable.

Also, if you perform a DIY installation then the window manufacturers that you’ve purchased from may not be obligated to uphold their guarantees. Companies or professionals must carry an accreditation from one of the following organisations in order to not to void the guarantee when they install your double glazing:

Fitting double glazing is also more difficult than it may initially seem, requiring more than a single person to complete. As such, performing a DIY project like this can be dangerous. Make sure to hire a qualified professional to make sure you’re as safe as can be while renovating your home.

Things to look out for

  1. Get lots of quotes! Some double glazing companies may use sales tactics to pressure you into purchasing windows on the spot – don’t fall for these. Shop around and make sure you get several quotes from local and national companies.
  2. Pay attention to the specification of the window. Check the specifications of the windows that you’re being quoted for and be clear on what type of window you’re looking for. You can use the double glazing energy efficiency rating scale as a guide and compare the U values of windows to understand their thermal efficiency.
  3. Non-standard window openings can add significantly to the cost of your replacement double glazing. This is because these will often need replastering and making good around the window frame. This means that the fitting will take longer and be more expensive.

Are you looking for replacement double glazing quotes? We can help. Complete the form below and we’ll connect you with up to 4 double glazing installers so you can get a fair price.