Buying double glazed windows – everything you need to know

Buying double glazed windows is a big decision. Not only is it a large investment, but as double glazed windows can last for up to 30 years or so, it’s a buying decision that you’ll have to live with for a very long time. Double glazing affects the look of your home, how energy efficient it will be, how warm it is and how much you pay on your energy bills. So, you must choose carefully.

And choosing carefully means you need to be armed with all the information about your choices before you take the plunge. But, if you get it right, it’s an investment that will pay off in the long run. We’ve put this buyer’s guide together to help you find out everything you need to know about buying double glazed windows.

Double glazed window frames

One of the first decisions you’ll probably make is which material you’d like your double glazed window frames to be made from.

Here, you’ve got three options:

  1. uPVC windows

uPVC frames have long been the most popular choice for double glazed windows. And for good reason. They’re the most cost-effective option and offer many benefits such as:

  • They’re incredibly durable – lasting for up to 35 years
  • Low maintenance – all they will need is an occasional clean with soapy water
  • They come in a range of colours and styles
  • The most sustainable choice – uPVC can be recycled up to 10 times. That means lower carbon emissions by making less new plastic. And thousands of tonnes of waste is saved from going to landfill every year
Double Glazed Windows

2. Aluminium windows

Aluminium double glazed windows have risen in popularity in recent years, thanks to advances in technology. Being metal, aluminium conducts heat which, years ago, meant heat easily escaped through them. However, modern aluminium windows have a thermal barrier within the frames that stops that from happening.

Aluminium windows have many other benefits too:

  • Durable – lasting for up to 30 years
  • They are low maintenance – all they will need is an occasional clean with soapy water
  • Come in a variety of colours
  • Lightweight, yet incredibly strong – this makes them almost impossible to break and therefore best for the security-conscious
  • Their frames are narrower than uPVC or timber frames – giving maximum glass space to let in more light
  • They’re 100% recyclable – making them a sustainable choice

 3. Timber windows

Timber windows are perfect if you have a traditional or period style property. They do cost more than uPVC and aluminium, but, as modern timber windows are treated to prevent fungus and rot, they can last a long time if they are looked after. Here are some things you need to know about timber windows:

  • They need regular maintenance – if you do buy timber windows always check the manufacturer’s recommendations with regards to maintenance. But as a guide, you can expect your windows to need re-staining or painting 10 years after they’re installed, and then around every 5-10 years after that
  • You can change their colour – this is a benefit of the frames being paintable
  • Timber is recyclable as it’s a natural material. And to ensure your windows have come from a sustainable source, look for FSC (the Forest Stewardship Council) certified wood

Double glazing frame colours

uPVC windows come in colours ranging from varying shades of white to greens, beige, greys, browns and black. You’ll also find some woodgrain effects that are almost indistinguishable from real wood.

Aluminium frame colours are usually a little more limited, but you can still expect to find white, cream, grey, brown and black.

And of course, when it comes to timber, the colour will depend on the type of timber you choose. Plus, there is always the option to paint it, in which case, you can choose any colour you like.

One other thing to be aware of when choosing your frame colour is that with uPVC and aluminium frames, you can have a dual colour. This means you can have a different colour on the inside to the one you have on the outside. Of course, this is possible with timber too, as you can always paint the frames if you want to.

Styles of double glazing windows

When it comes to styles, you’ve got a lot of choices. Often, people simply replace their old windows with new windows in the same style. But it’s worth considering others. The most important thing is to choose a style that suits both your personal taste and the architecture of your home. Here are the most common styles of double glazing windows available:

Casement windows

Casement windows have hinges at the side of the frame and open outwards. They’re held open with either a stay (a metal bar with holes that slot over a peg) or a friction hinge or crank mechanism.

Sash windows

Sash windows consist of two panels, one above the other. They open by sliding up and down vertically. Sash windows can be double-hung, where both panels move, or single-hung where only the bottom panel can be moved.

Bay windows

Bay windows consist of three or more panels that protrude out from the home in a curved shape. Typically, the middle section is larger than the two side panels. Bay windows are very attractive from the outside and help to make the room inside more spacious.

Tilt and turn windows

Tilt and turn windows have a clever hinge mechanism that allows them to be opened in two ways. They can either be opened with hinges on the side, like a casement window, except the window opens inwards rather than outwards. Or they can be tilted from the bottom with the top of the window angled
into the room. This allows for ventilation, but with increased security as the gap is too small for anyone to fit through.

Custom shaped windows

If you wanted something other than square or rectangular windows, some companies make windows to specific shapes and dimensions. So, arches, round windows and even angled windows to suit a sloping roof are all possible.

Sliding doors

Sliding doors are popular for windows leading out to a garden. They consist of two or more panels depending on the size of the opening. Either both or just one of the panels can be opened and the panels slide to sit one behind the other. They’re a great space saver as, when opened, they don’t take up any room either inside your home or outside in your garden.

French doors

French doors, sometimes called French windows, are double doors that are hinged at the sides. They can open inwards or outwards. This is another great option for doors leading out to a garden.

Bi-folding doors

Bi-folding doors usually consist of several panels that are all hinged together. When they are opened the panels collapse back onto themselves like a concertina, and then they can be slid to one end of the frame to create an opening. They are very modern and allow you to have a much larger opening than
sliding doors. However, when open they will protrude slightly into your home and garden.

Types of double glazing glass

As the name suggests, a window that’s double glazed has two panes of glass within each window frame, separated by a spacing bar. The gap is there to trap warm air and slow it down from leaving your home.

Some double glazed windows go further than this. The gap between the two panes of glass is filled with a gas called argon, which slows the loss of heat even further.

Gas-filled double glazing is usually more expensive than non-gas filled windows, but they offer the best in energy efficiency, keeping your home warmer and saving money on energy bills.

Another option is triple glazed windows. These have three panes of glass in the frame instead of two, again, separated by spacing bars. The benefits of triple glazing are that your home will be even warmer and even more energy-efficient. But when it comes to reducing noise, double glazing is actually better.

Naturally, triple glazed windows will cost more than double glazed, so it’s worth weighing up the cost versus the extra benefit. If for example you live on the seafront and your home is blasted by cold winds, or your home has north-facing rooms that get extremely cold, then it may be worth the extra cost.

But it’s not all about the number of panes of glass you have. It’s about the glass itself. There are several options available such as: 

  • Low e-glass – this has a reflective coating that reflects heat back into your home
  • Low iron glass – this is clearer than other glass and allows more light into your home
  • Security glass – this is either thicker, tougher or laminated so it’s impossible to smash through
  • Obscured glass – this is the ‘cloudy’ glass that’s used for bathroom windows or any other windows where you need privacy

Double glazing window furniture

Window furniture is the collective name double glazing companies give to the fittings that come with a window, such as the handles, stays, fasteners and latches. They come in all sorts of styles and finishes. From ultra-sleek and modern styles in white or chrome to more ornate or traditional styles in pewter or gold effects. Whatever you choose, it must match the style of your windows and the inside of your home.

Energy efficiency

Buying double glazed windows that are energy efficient is probably one of the best things you can do for your home, your finances and the environment. All double glazed windows are tested and given an energy efficiency rating by The British Fenestration Rating Council (BFRC). It’s the most trusted rating council for verifying the energy performance of windows and doors. Energy ratings range from A++ (the best) to E (the worst). You should aim for a rating of C or above to get the greatest benefit.

The cost of double glazing

The cost of double glazing can vary considerably depending on:

  • The quality
  • Style
  • The glass
  • How many windows and their size
  • The type of locks
  • Whether scaffolding is needed
  • Your location
  • Access to the property
  • The company you choose

As a rough guide, the average cost to double glaze a three-bedroom house could be between £4,000 and £5,000. And costs can vary massively between different companies. 

So, it’s always best to get up to four double glazing quotes. When it comes to payments, all reputable companies will accept debit or credit card payments, and many will offer finance options as well. If you do decide to take out a finance option, make sure the company you use are authorised and regulated by the Financial Conduct Authority (FCA), so you’re protected if anything does go wrong


All double glazed windows are good when it comes to security. But, if you’re particularly intruder conscious, look for these features:

  • Double glazed glass is extremely tough and almost impossible to smash – but toughened glass offers the best protection
  • Aluminium frames are incredibly strong compared to uPVC and timber, so are the best option for security
  • Multi-point locking systems lock the window in at least two locations. But you can get these systems that lock in more than two and the more locking points there are the better. Some windows can have up to eight

Multi-point locking systems allow you to leave a window on the latch (where it’s locked in a slightly open position). However, a completely closed window is more secure than an open one. So, opt for windows with a trickle vent. These are thin bars at the top of the window frame that let in air. They can be closed if it’s very cold.

Don’t only consider security in terms of keeping intruders out – think about safety. If you have young children, for example, you may prefer to have locks on the upstairs windows as well as downstairs. Windows can also come with restrictive openings, where they can only be opened wide enough to ventilate a room, but not enough to risk being able to fall out. These openings can often be turned off so if you do need to open the window wider at times, you can.

Look for trusted double glazing companies

There are literally thousands of double glazing companies in the UK, so it’s not surprising buyers can become overwhelmed when buying double glazed windows. First, consider whether you would prefer to use a large well-known national company or a small independent local installer. There are benefits to both.

Many people prefer to use small independent companies. They tend to offer a more personal service, where you’ll be dealing with one person throughout the whole process. They can also offer the same quality products at much lower prices than national companies.  This is because they don’t have huge overheads such as teams of salespeople and advertising costs, unlike the national companies.

But, of course, some homeowners prefer the security of using a big brand installer. And they often run deals and promotions and are more likely to offer finance options.

Whoever you choose it’s important to do your homework:

  • Check they are registered with either FENSA (The Fenestration Self-Assessment Scheme) or CERTASS (Certification and Self-Assessment). Both are government authorised schemes that monitor building regulation compliance for replacement windows and doors
  • Ask to see photos, or visit a couple of local homes of their previous installations to check the quality is of a high standard
  • Check out their customer reviews online
  • Choose a company that offers a lengthy warranty (at least 10 years). And check that it covers all parts of the window, not just the glass

We always recommend you get up to four double glazing quotes to give you the best chance of finding a company you trust at the best price.

If you’re ready to get started, we can help you get in touch with reputable and trusted double glazed window companies in Hampshire, Dorset, Wiltshire, Surrey, Berkshire or Sussex, or anywhere else in the UK. We’ve already done the hard work of vetting the companies we recommend, so you don’t have to.

Fill in our online form and get up to 4 FREE double glazing quotes within 24 hours. Or contact us Link if you have any questions. We’ll be happy to help.