What is Double Glazing?
One of the simplest ways of understanding what double glazing is & how it works is to think of a humble sandwich. In this example the “bread” will be made from panes of glass and the “filling” will be an air gap.
The gap is maintained by using spacer bars around the outer edge of the glass. The size of the air gap can be varied from 6 to 20 millimetres.
The wider the gap, the better the energy insulation and sound reduction properties.
Sometimes the gap is filled with a heavy inert gas such as Argon to improve insulation.
So there you have it – double glazing is a glass & air sandwich!
How Much Does Double Glazing Cost?
On average, the price of a double glazed casement window in white UPVC will be approximately £300. That would be based on a size of 1 metre x 1 metre.
If you want one a little larger at 1.2m x 1.2m the price will increase to approximately £350 to £400.
What are the main factors for double glazing prices?
There are, of course, a number of different factors influencing the eventual cost of double glazing for your property.
These factors will include the size and shape of the windows you choose, the style or design, the materials used in the construction of the frames and the number of windows you order.
You can also add 2 more things to the list. Because who you buy the windows from, and where you live in the country, can also make a difference to the cost of double glazing (here are some handy tips about buying)
If we look at the basic property types:
- To replace the old windows with new double glazed windows in a flat, maisonette or apartment, the cost is going to vary between £1,500 and £2,800.
- For a big 3/4 bed semi, or smaller detached house, a brand new set of units would require a higher budget of somewhere around between £5,000 and £8,000. This would be for 10 to 12 white uPVC windows.
In terms of the average guide prices above, these would be what you could expect from local or regional, double glazing installers. Local independent suppliers have built up quite a good reputation over recent years of being able to offer high spec products, well fitted installations with proper customer service in terms of aftercare.
One of the most often quoted advantages of “going local”, is that local replacement window companies can offer very good pricing compared to the “Nationals”. This is likely because they don’t have to carry so much overhead costs. Costs such as big advertising campaigns and hefty commissions to sales reps (which mostly get passed onto the consumer).
When you are about to invest your hard earned savings in (or even take out financing for) replacement double glazed windows, it’s the sensible thing to do as much as you can to get the best quality products at the most competitive prices.
As we mentioned beforehand, the average quoted price from local suppliers for 10-12 windows start at around £5,000. But, if you have 4 or 5 quotes from different companies, it’s entirely possible to leverage these quotes as a negotiating tool to try to get the work done at an even lower cost.
Having installers compete with each other over prices can very often result in getting more for your money (free upgrades such as low-e glazing or gas filled sealed units). If you play your cards right, you also stand a really good chance of a decent discount on the installation cost.
One of the easiest & quickest way to get independent double glazing prices, is to use our quote request form (just a few simple details about you & your project are required).
Double Glazing: What are the advantages & benefits?
Before you embark on what is most certainly quite an expensive home improvement (depending on the size of the project of course), it’s prudent to consider what you are going to gain over the long term and whether that will justify the investment.
The primary benefit that most often gets mentioned is the potential money saving that can be made by fitting energy efficient replacement windows. Modern double glazing helps retain more heat, keeps out more cold, eliminates cold draughts and fights condensation.
- According to Which.co.uk, 44% of homeowners buy double glazing just to reduce energy bills.
- Try out this calculator for yourself: https://www.myglazing.com/ggf-energy-savings-calculator/
Being able to run the central heating less often and at a lower temperature will significantly reduce your heating costs. Given that your new double glazed windows could last for 20 to 25 years, the savings can very often amount to more than it cost to buy them in the first place.
Another important feature of new double glazed windows are the safety & security elements. Just having 2 panes of glass makes them harder to break accidentally, thereby lowering the risk of personal injury. Most units are fitted with internal window beads, meaning the glass cannot be removed from outside the property. Alongside this you also have multipoint locking systems that are highly secure.
You can’t put a price on peace of mind or the safety your family. Whilst possessions can be replaced, why put them at risk with insecure windows & doors?
Did you know that some insurance companies offer reductions on their home insurance policy premiums if modern double glazed windows & doors have been fitted? Certain conditions will apply, so check your policy schedule or contact your provider to find out more.
What are the different types of double glazing?
Replacement windows are a big market in the UK. There is a really wide range of different appearance and functionality amongst the products currently on offer.
Here we will take a quick look at the main features & benefits of the most popular designs. We will also cover some examples of average prices in the market from local and regional suppliers (prices may not include fitting or taxes).
Casement Windows: White UPVC
Mainly due to widespread competitive pricing matched with contemporary styling, UPVC Casement windows are one of Britains’ most popular designs.
Available in both fixed or opening versions, dependent on your requirements, they can be configured to open in or out.
The typical outward opening casement allows for plenty of fresh air to circulate. They can have movement limiters fitted, such as night latches, so that you can benefit from the fresh air without having to worry about an unwanted visitor (human or animal) getting access.
In terms of function, you can have them fitted to be hinged from either side (left or right), top or bottom. Top hung versions are usually called Awning casements. Bottom hung versions are called Hopper windows.
What are UPVC Casement Windows Prices?
(All Sizes in Millimeters Height by Width)
- 500 x 500 (non-opening) £150-£180
- 1000 x 500 (non-opening) £170-£210
- 1000 x 1000 (non-opening) £210-£250
- 500 x 500 (single opener) £260-£300
- 1000 x 500 (single opener) £270-£350
- 1000 x 1000 (single opener) £300-£400
French Window: White UPVC
One of the more stylish and classic variation on the casement design is the French window. This design, in effect, is 2 casements fitted side by side within a single frame.
The design can come with or without a centre mullion post (where the opening sections meet in the middle). The centre posts makes the windows more secure as the frames lock on to the post instead of each other. However, the centre post can obstruct the view and additionally, this version is costlier.
Once again, they can be set up to open in or out, with outward being the more favoured. With both sides open you will benefit, not only from a great view of the outside, but also plenty of fresh air.
In general, a French window will cost quite a bit more than a standard casement version.
What are UPVC French Windows Prices?
(All Sizes in Millimetres Height by Width)
- 500 x 500 White UPVC French Window £450 – £500
- 1000 x 500 White UPVC French Window £480 – £550
- 1000 x 1000 White UPVC French Window £500 – £550
- 1200 x 1200 White UPVC French Window £550 – £600
Tilt and Turn Windows:
This design is one that can divide opinion, but is actually quite popular and unique. Tilt and Turn windows work in a way that allows them to open in 2 completely different directions:
- Moving frame opens inwards on side hinges.
- Moving frame tilts inwards on bottom hinges.
The opening function is controlled by a single handle, dependent on which way you turn it. Moving the handle in one direction operates the tilt function, move it in another direction and the turn function is released. You cannot tilt & turn a single window at the same time.
The tilt function allows the window to “lean” backwards into the room. The amount of tilt is limited for safety reasons. This function allows for great ventilation.
Using the turn function allows the window to be opened like a regular casement. The standard turn function only allows for the window to open inwards.
The fact that both the functions only allow for inward opening is what can put off some homeowners from going for this type of design.
What are Tilt and Turn Windows Prices?
(All Sizes in Millimeters Height by Width)
- 800 x 800 UPVC Tilt & Turn Window £400 – £450
- 1000 x 800 UPVC Tilt & Turn Window £450 – £490
- 1000 x 1000 UPVC Tilt & Turn Window £500 – £550
- 1200 x 1200 UPVC Tilt & Turn Window £500 – £575
This design is often associated with older, pre-war properties, such as Georgian or Victorian. The vertical sliding Sash window is truly an all-time classic.
The design is characterised by having 2 sections, top & bottom. The opening function of the sash window design is to slide the moving section either down or up.
Where both sections can open, they are called “double hung”. Where only the bottom section can move, they are known as “single hung”.
The standard option is for a single hung version, where the bottom section slides upwards. Due to the counterbalance system, you can slide them up as much, or as little, as needed. Can also be considered as a good means of escape in an emergency.
With the double hung version, you can open both sections at the same time.
These are quite complex to manufacture, as there needs to be a counter- weight system built into the outer frames.
This complex construction translates into quite a considerable price increase when compared to a standard casement window. The higher price of sash windows has led many homeowners to go for a lower cost option, such as false sashes, when they need to be replaced.
What are UPVC Sash Windows Prices?
(All Sizes in Millimetres Height by Width)
- 500 x 500 White UPVC Sash Window £500 – £600
- 1000 x 500 White UPVC Sash Window £600 – £700
- 1000 x 1000 White UPVC Sash Window £650 – £750
- 1200 x 1200 White UPVC Sash Window £750 – £900
Bay & Bow Windows
Both of these designs are what are known in the industry as projection windows – in other words they protrude from the property.
The major difference between the 2 styles is that bow windows have a curved appearance, whilst bay windows make use of angled sides.
Because both of these designs protrude from the main building, you may have to consider the extra costs of “roofing & flooring” the windows.
Of the 2 designs, bay windows are going to need a proper “roof & floor”. A bay window does not usually project out as much as a bay, and therefore need less work in this area.
Bays & Bows can be built from either casement of sash window elements. Both of these types of window cost significantly more than a regular design.
There are some nice variations on the theme such as Canted & Oriel bays.
What are UPVC Bow & Bay Windows Prices?
It’s very difficult to give a price guide for a bow or bay window as they are usually bespoke items built specifically to order for a particular client. Given that each job is going to be different, it means that you can’t really give an “average cost”.
The actual cost of fitting a bay or bow window, will depend greatly upon the material used and the number of panels in the design. However, as a rough guide, here are some potential costs.
Bay Window Costs
- 3 Panel UPVC Bay Window £1,100 – £1,200
- 4 Panel UPVC Bay Window £1,500 – £1,700
- 5 Panel UPVC Bay Window £2,000 – £2,500
Bow Window Costs
- 3 Panel UPVC Bow Window £1,100 – £1,300
- 4 Panel UPVC Bow Window £1,500 – £1,800
- 5 Panel UPVC Bow Window £1,800 – £3,000
Which type of double glazed window is the best?
The answer is going to be heavily influenced by personal preference and, of course, your budget. But it’s also fair to say that some double glazed windows will clearly be better for the job at hand than others.
For example, if your property & the surrounding properties are fitted with Sash windows, then it’s going to make your home “stand out like a sore thumb” if you decide to install Tilt & turn. It may even damage the desirability and resale value if you did so.
But, as a matter of appearance, convenience, availability, price competitiveness, lifespan and security, UPVC casement windows represent a really good all-round solution for many homeowners.
The best performing double glazing, however, is surely going to have a high Window Energy Rating (WER) such as A++, combined with a long lasting secure frame.
The high energy efficiency is achieved by adding a metal oxide coating (Low-E glazing) to the outer side of the glass, so that it “bounces” the heat back into the house.
Filling the space between the twin panes of glass in the sealed unit with a heavy gas such as Argon also improves insulation.
Did you know (according to a which.co.uk survey), that almost 50% of people who bought replacement windows did so specifically to help reduce their energy bills?
If your budget does not extend to top of the range double glazing, and you opt for a cheaper version, you need to keep in mind that C-rated windows are the minimum requirement to meet the UK building regulations.
What are the main window and frame features?
The thickness of the double glazing itself is important. Most double glazed units are between 14 to 28 millimetres thick. The wider the “air gap”, the more energy efficient.
As mentioned beforehand, the energy efficiency can be improved by adding Argon gas. Using Low-E glass and “warm edge” spacers will also raise the performance levels.
Frames come in different materials, such as UPVC, timber and Aluminium. Each with their own particular USP (unique selling point).
UPVC holds the position of being most popular due to having lower prices than hardwood and Aluminium. It’s a lot easier to maintain than timber and, of course, does not rot or need painting like timber windows do.
Hardwood windows appeal to many because it’s a natural material that does have along lifespan when looked after. Engineered timber, a useful modern alternative to hardwood, is making its presence felt in the market. This is especially true for those property owners that feel plastic or metal windows are not suited.
The use of aluminium frames is also on the increase. One particular feature of using an aluminium frame is that it can be made a lot slimmer than UPVC or timber. Slimmer frames are possible due to the natural structural strength of aluminium – you get “more glass, less window frame”.
Should you buy triple glazing?
Looking at a house from the street, you really won’t be able to tell whether it’s fitted with double or triple glazing. The difference, however, becomes very apparent once you have triple glazing installed.
Triple glazing in the UK is not a big market, mainly because the UK weather (although grey & miserable a lot of the time) is not that severe. As an example, unlike Scandinavian or Nordic countries where winters can be extremely cold.
However, there is no doubt that triple glazing has measurably better energy efficiency and better sound proofing than double glazing. It can be up to 18 degrees warmer than a single glazed room and between 2 to 7 degrees warmer than a double glazed room.
Triple glazing is especially beneficial if you live in a noisy neighbourhood. The sound from the outside is deadened by the extra layer of glass combined with the second “air-gap”. In this instance, the quality of life improvement may well justify the extra purchase costs.
However, you can make double glazed windows more soundproof by just having inner and outer panes of slightly different thicknesses.
In terms of price, you will have to pay a premium for triple glazed windows, they are costlier than double glazed. This extra cost may not be offset by increased savings on your energy bills.
Quick FAQ – 5 Common Double Glazing Questions & Answers
1Do I need planning permission to fit replacement double glazed windows?
In the majority of cases, you won’t need planning permission, but you will have to get the windows certified as meeting building regulations.
If you live in a listed, or historic building, an area of outstanding natural beauty or conservation area, you should consult with your local planning as you may need permission to make any changes.
If you use a CERTASS or FENSA registered installer, they will certify your windows meet UK building regulations for you. Otherwise you have to do it yourself.
2Which double glazing company is the cheapest?
Buying replacement windows based on the best value for money within your budget is a better way to go.
Buying on lowest price alone can sometimes lead to you ending up with more problems than you started with. Don’t forget, that the supplier will have been looking for the cheapest component to make the windows.
In general terms, a well-established local business with a good track record should be able to supply your windows at lower prices than a big National brand. It’s likely that it costs less for them to do business because they don’t spend so much on salesperson commissions or high profile advertising.
There’s going to be a lot of variation in prices because each job is different. The best way to find out is to get quotes from both local & regional companies to compare prices.
Here is a quick summary of some local UPVC windows prices in the market.
- Flat 4 or 5 windows £1,500 – £2,900
- Small house 8 or 9 windows £3,500 – £5.000
- 4 bed semi 10 or 12 windows £5,000 – £7,900
- Detached house 15 to 18 windows £7,500 – £12,000
3How do I know when to replace my old windows?
There are definitely going to be signs that your old windows need replacing, although some may not be too obvious at first glance.
Here are a few pointers
- Loose or broken handles & hinges: Badly fitting windows due to faulty hinges can allow wind or water to get in. Broken locks can let intruders in.
- Frame seals failed: Rubber gaskets that keep the unit water tight, can perish; as can silicone sealant around the frames: If you can’t get repairs, then it’s time to replace.
- Glazed unit seal fail: If the sealed units are leaking it can cause condensation and let all your heat out. Seals can be repaired, but it’s sometimes much better to replace them.
- Visual degradation: Timber frames can rot; old fashioned aluminium frame surfaces can become pitted & scarred, poor quality uPVC can go yellow. If your windows look a mess it will lower the value of your home.
Take some time out to do a thorough check of your existing installation. Some problems caught early on can save you a lot of money later.
4Is it worth paying extra for Argon gas?
I saw a quote from one installer that priced Argon gas at around £12 per square metre. As that is about the size of an average window, if you need 10 windows then, at this rate, the cost is going to be around £120 for the whole house.
What you get is a slight increase in overall energy efficiency. More effective gases are Krypton & Xenon, but they are also costlier than Argon.
The gas is expected to leak at a rate of around 1% per year, so even long term that’s not so bad. But badly made seals can allow the gas to escape much quicker.
An alternative, if you only have the budget for 1 “upgrade” is to use Low-e glass coatings. It offers more energy efficiency than Argon, and of course, it doesn’t leak!
5What type of guarantees do I get when I buy replacement windows?
It will be unusual if your supplier does not provide at least a 10-year guarantee on the windows themselves.
However, what exactly is covered will only be revealed by the policy schedule. Which you should read properly. Frames & sealed units may have separate terms & conditions attached. Moving parts should also be covered.
Warranties on the installation work should be part of the contract, although the terms of the warranty can vary from contractor to contractor.
One other element to consider is whether the company who fits your windows will be in business long enough to honour the warranty, should there be a need to claim.
Alongside this are deposit guarantees. Your supplier should provide an insurance backed deposit guarantee (IBG) that protects your money. Choosing to deal with a GGF, FENSA, CERTASS or DGCOS member should resolve this concern as all these trade bodies insist on, or provide an IBG for their members.
Firstly, don’t be in a rush to part with your money, take your time to think about what you want, come up with a budget then do your best to stick to your plan.
Work with certified or accredited companies, this will allow for better consumer protection and reduce the likelihood of ending up with a “cowboy builder”.
Get a professional to survey your home and come up with a recommendation and provide written quotes. Getting everything in writing avoids potential misunderstandings.
Don’t just get 1 quote, get at least 3 or 4. That way you can easily spot who is over or under-priced. Remember, if the deal looks too good to be true, then it probably is.