How Much Does Double Glazing Cost?

If you want to make your home more energy-efficient, block out some external noise and, potentially, make your property more secure, you might like to know the cost of double-glazed windows? But how much does double glazing cost? We consider the current price of double-glazed windows and weigh up some of their pros and cons.

What are double-glazed windows?

Double-glazed windows comprise two panes of glass, separated by a sealed gap. The space between the panes is sometimes filled with a gas, such as argon, or left as a vacuum. Double-glazed windows provide superior insulation against temperature and noise than traditional, single-pane glazed windows.

The glass used in double-glazed windows can be laminated or UV-tinted, but is otherwise similar to the glass used in single-glazed windows. There are also triple-glazed windows, which are more commonly used in colder parts of the world. Generally speaking, double-glazed windows can be added to a property in either of two ways:

• Custom-made double-glazed windows: are produced and installed as a single unit made up of two panes of glass. This approach is commonly used for the windows and doors of new homes and extensions, when the building work is being done from scratch.
• Retrofit double glazing or secondary glazing: is when new double-glazing panels are fitted to the existing window frames of a home. For those renovating existing homes, retrofitting can be a cheaper option than purchasing new custom-made double glazing.

How much do double-glazed windows cost?

Double-glazed windows and doors are most commonly priced by the square metre. In our research, we found the cost of double glazing in New Zealand starts at around $450 per m² for the supply and installation of double glazing into an existing aluminium frame.

However, exact pricings vary widely, as there are many variables to consider, such as window size, frame materials, the type of glass used and its thickness. For example, the same company that quoted us $450 for the 1m² glass pane, quoted $1207 for a 2m² pane. This is four times the amount of glass for under three times the price – so the size of the glass panes you require is a big factor in their cost.

And if you’re purchasing new frames, your choice of framing material will affect the overall cost, too: aluminium frames and uPVC frames are the cheapest, starting around $550 for a 100cm x 60cm window, while new timber frames can cost upwards of $1000 per m².

Your home’s location and whether you’re replacing second-storey windows that require the use of scaffolding will also affect the price of your new windows.

So, ultimately, asking a double-glazing company for a quote is the only sure-fire way you’ll be able to get an exact costing for fitting double glazing in your home.

Just remember that, as with all building work, it’s advisable to obtain multiple quotes from a range of building firms, as quoted prices can vary enormously.

What factors can affect the cost of double-glazed windows?

It can be difficult to work out the precise cost of double glazing without taking into consideration your specific circumstances. This is because your home’s entire window configuration will need to be factored into the estimate.

For example, existing single-glazed window frames might not be able to support the thickness of double-glazed windows, and therefore be unsuitable for retrofitted double glazing. This means that new custom-made frames might be required, and this could affect the overall cost of the project.

Some of the key factors that can determine the cost of double glazing include:

• Frame material – expect to pay up to $1500 per square metre for top-quality, timber-framed, double-glazed windows. Aluminium and uPVC double-glazed windows will likely cost less.
• Glass type and specification.
• Style of window.
• Window hardware required. As a general rule, the more components a window has, the more expensive it will cost.
• Window size.

→ Renovating a home could change what insurance cover you may need:
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What are the payment options for double-glazed windows?

How you decide to pay for the work can depend on its cost. There are several options available for would-be home renovators to consider, including drawing on savings, accessing funds through a home loan, taking out a construction loan, personal loan or green loan, or paying on a credit card.

Drawing on savings: is generally the cheapest and most straightforward way to pay for work around a home, as it will avoid interest costs and the need to apply for finance.

Drawing on a home loan: is an option if you’re replacing multiple windows, or the work is part of a more extensive renovation. If you’re ahead with your home loan repayments and have an offset account or redraw facility linked to your mortgage, you might be able to access funds without refinancing.

Taking out a construction loan: could be an option if you’re building a new home or planning a major renovation. A construction loan is a type of home loan that allows funds to be drawn down at various stages of the project. This means that you don’t pay interest on the full loan balance until the project is complete, which can be a valuable money saver.

Taking out a personal loan: could also be an option. You could take out a secured loan, or an unsecured loan. It’s worth keeping in mind, though, that interest rates are generally higher for personal loans than for home loans, and that it’s a good idea to read the lender’s terms and conditions first. You can compare personal loans with Canstar.

Taking out a green loan: can help you fund home improvements that will make your home more energy-efficient, which can save you money in the long run. Not all banks offer green loans, and those that do typically specify exactly what projects qualify. Some lenders include double glazing on their list of approved projects, as it is often considered an eco-friendly addition to a home. Green loans often come with interest rates well below the rates offered on regular mortgages and personal loans.

Paying by credit card: may also be possible, depending on the cost of the glazing project and your ability to repay the debt quickly. There could be some potential benefits for doing this, such as extra insurance cover or rewards on your spend. But keep in mind that credit card interest rates are typically much higher than those for home or personal loans, and interest can quickly accumulate on large balances. It’s a good idea to weigh up your options and consider them carefully. If you don’t think you’ll be able to pay off the card’s balance in full each month, it may be worth seriously re-considering whether a credit card is the right option for you.

How to save on the cost of double-glazed windows?

While installing double-glazed windows is unlikely to be a cheap undertaking, you may be able to save money by making some savvy choices.

Think carefully about colours and window styles that can add to the cost. Choosing simple openings, aluminium rather than timber frames, and selecting awning or casement windows, are all potential ways to save.

You may be able to reduce the cost of adding double-glazed windows to your home by doing some of the work yourself, such as measuring, ordering and purchasing the materials for the window or windows, and then paying a skilled tradesperson to fit them.

But even this preliminary work is likely to require a degree of knowledge and skill. So before you jump in yourself, it could be worth thinking carefully about the risks of doing it yourself.

And, of course, regardless of which style of double-glazed window you choose, there’s the age-old method of getting bang for your buck by simply shopping around for the best-value supplier. If you obtain a number of quotes from different companies, you might be surprised at how their prices vary. Just make sure you’re comparing apples with apples, i.e. the same kinds of glass, frames, etc.

What are the benefits of double-glazed windows?

Some of the potential benefits of adding double-glazed windows to your property include:

• Energy efficiency: the thermal insulation delivered by double glazing means it can help reduce your heating bills during winter, and your aircon running costs during warmer months.
• Noise reduction: double-glazed windows provide significant insulation against external noise pollution, such as from cars and planes.
• Property value increase: modern glazing, window frames and improved insulation can help increase the value of a home.
• Security: a double-glazed window is harder to smash than a traditional single-pane one, and therefore can be more of a deterrent to burglars.

What are the disadvantages of double-glazed windows?

Some of the potential drawbacks of installing double-glazed windows can include:

• Upfront costs: it could many years for you to recoup the cost through energy savings. You also have to consider the potentially higher costs involved if your double-glazed windows need to be replaced in the future. Also weigh up how the installation could impact on other features of your windows, such as any blinds or shutters that are already installed.
• Fit of window style: this can be an issue, as it’s not always possible to find double-glazed windows that fit the style of certain properties – particularly older ones. However, retrofitting existing windows could be an option.
• Added weight: if you’re  installing double-glazed windows on an existing property, the added weight of the new double glazing could be an issue, particularly on an older building. Possibly, it could cause materials around the window to warp out of shape over time.

Can double glazing save you money on energy bills?

One of the main potential benefits of double glazing is the impact it can have on your home’s energy efficiency, and the potential knock-on effect on the amount you spend on your energy bills.

A single pane of glass is not generally a good insulator. Add a second pane, though, and the difference can be significant. And windows can be responsible for up to 40% of a home’s heating energy loss.

However, any actual savings specific to your household will depend on factors such as the size of your home, the quality of the double glazing and the climate where you live and, of course, how much your annual energy bill is to start off with.

About the editor of this page

Bruce Pitchers is Canstar NZ’s Content Manager. An experienced finance reporter, he has three decades’ experience as a journalist and has worked for major media companies in Australia, the UK and NZ, including ACP, Are Media, Bauer Media Group, Fairfax, Pacific Magazines, News Corp and TVNZ. As a freelancer, he has worked for The Australian Financial Review, the NZ Financial Markets Authority and major banks and investment companies on both sides of the Tasman.
In his role at Canstar, he has been a regular commentator in the NZ media, including on the Driven, Stuff and One Roof websites, the NZ Herald, Radio NZ, and Newstalk ZB.
Away from Canstar, Bruce creates puzzles for magazines and newspapers, including Woman’s Day and New Idea. He is also the co-author of the murder-mystery puzzle book 5 Minute Murder.