We’ve all heard stories of unscrupulous double-glazing salespeople, who will quote ridiculous prices just to see whether they can get away with it. Unsurprisingly, there’s a lot of anxiety and confusion around the whole experience of buying new windows as a result.

Double-glazed windows are a major purchase, and many of the glaziers we’ve spoken to, who have years of experience in the windows trade, agree that you get what you pay for. But what exactly are you paying for? To find out, we talked to some of our traders to discover what goes into the prices of windows.

Use Which? Trusted Traders to find a glazier in your area now.

A bespoke price for bespoke double glazing

Everybody has a different interpretation of what expensive means when it comes to double glazing. As Kirk Williams from Cloudy2Clear says, ‘Some clients will say they thought it would be more, and others will say they didn’t realise it would be that much.’ But, for a lot of people, the price of replacing double glazing can come as a surprise.

What many people don’t realise is that each window is a bespoke product. Only a tiny minority of properties, usually new builds, can make use of ready-made windows that you might find in a DIY or hardware store. If your window measurements differ by even a few millimetres, these products will not fit. However, some unscrupulous builders might try to fit them incorrectly by cutting them to size or adding trims, which could leave you with poorly secured, draughty windows.

The cost of a bespoke product is always going to be higher than for something that is mass produced. A  & A Windows Direct Ltd’s Alfred Jenkins explains how the ordering process works:

‘We go to people’s houses, measure up and price the windows accordingly - either in their house or in our showroom. If they decide to go ahead, a surveyor goes round and brings all the drawings back. We then put them into the computer and the computer order goes to the manufacturers.’

There is a supply chain starting from when you, the consumer, choose your window. The window-fitting company does not manufacture the double-glazed windows, but rather sources them from a supplier. As windows are a composite product, made up of glass and frames, those separate parts may in turn be sourced from different factories. This is because of the different equipment required to produce each element that makes up the finished product.

To find out more about the average costs for different types and sizes of double-glazed windows, see our Which? guide to double-glazing prices.

Variations in design affect double-glazing prices

The specific make-up of your bespoke window will also affect how much it costs. Your double-glazing company will give you a choice of what kind of window you want – including the level of energy efficiency, colour, design and security features.  Some windows will be more or less energy efficient; others will have better security features. Each of these variations will affect the price because of the processes or raw materials involved.

For example, an increasingly popular variation on a standard smooth, white, uPVC frame is one with a wood effect. This involves putting an extra layer of grained foil on top of the smooth uPVC, plus the paint, and this extra process adds to the price. Wood-effect uPVC frames typically cost around 15-20% more than plain white frames.

In other cases, the raw materials themselves can add to the cost. A double-glazed window with aluminium frames will cost 30-50% more than one with uPVC. Timber windows also typically cost more than uPVC, because the timber is usually made from blocks, glued together, which is an additional manufacturing process.

Sash windows are more expensive because of the complexity of both their manufacture and their fitting. The sliding sashes that allow the window to open and close need to be perfectly balanced to take the weight of the window. The materials involved are part of the cost, plus the man labour in the factory.

In a way, it’s like buying a car. Both basic and luxury vehicles will get you from A to B, but their engines, bodywork and extras will make a big difference to the experience. A basic uPVC double-glazed window will fill the space in your wall, but the extras will make the difference to the level of draught proofing, reduction of heat loss, and the look and feel of the window. This is what people mean when they say, ‘you get what you pay for.’

How to reduce the cost of double glazing

1. Keep your plans simple

If you want to keep costs down, keep your windows simple. A smooth, white uPVC finish, with standard double-glazed A-rated glass, is going to cost less than most other options. Once you opt for a particular finish, for example wood grain, you will need to match that for all trims, beading and so on. This all adds to the final price.

2. Replace just the glass if you can

Sometimes a steamed-up window will be caused by a fault with the glass, rather than the window as a whole. If your window frames are still in good condition, it’s possible to replace just the glass if it’s broken or damaged.

Kirk Williams from Cloudy2Clear told us, ‘Aluminium, uPVC and timber frames have beading that goes in and clips to itself. It takes five minutes to remove the beading. It’s a quick job to take the beading out and put the new glass in. It’s a fast turnaround, there’s no drilling. You take the beads out, get the old glass out and then put the new glass in, put the beads back into place and they’ve got what looks like a brand new window.’

3. Shop around for double-glazing quotes

If you do need to replace the entire window, ensure you get quotes from at least three different companies. Don’t accept the first quote you’re given, particularly if you are put under pressure from sales representatives. If a price is available today, it will be available tomorrow as well, and probably next week, too, if they want your business.

4. Compare double-glazing quotes fairly

When comparing quotes, ensure you compare like with like. Make sure each quote covers exactly the specification of double glazing you would like, including the type of window you want, the level of energy efficiency, locks and security fittings, size and design. By ensuring that quotes all refer to a window of the same specification, you get a true cost comparison. Unscrupulous companies can attempt to confuse consumers by comparing different levels of ‘extras’ on their windows.

Check the Which? guide to double-glazing sales and quotes for more tips on working with double-glazing companies.

5. Find a reputable double-glazing installer

No one wants to fall victim to a cowboy double-glazing installer, so do spend some time finding out the names of companies that you should be able to trust. Which? Trusted Traders-endorsed glaziers all work to the Which? Trusted Traders Code of Conduct to ensure they treat customers fairly.

Thank you to Alfred Jenkins from A&A Windows Ltd, George Jenkins from Homeglaze and Kirk Williams from Cloudy2Clear for their contribution to this article.

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