Find a Window Installer you can trust near you.

You don’t have to, especially if you’re on a budget. If you’re only replacing some, it’s a good idea to get all the windows on one side of your property replaced at the same time, so they all look the same. Be aware, obviously, huge savings could be had by having a number of windows replaced at the same time.

You can only repair blown double glazed windows in the sense that you can replace the sealed unit (the glass part of the window) instead of having to replace the entire window.

When a double glazed window is blown, it means that the seal around the window has failed and is now letting air in and out. Often the first sign that the sealed unit has blown is condensation on the inside of the window, which is annoying since there’s no way to get rid of it! When your sealed unit has blown, you’ll be losing heat out of the window, meaning you could be spending more on your energy bills.

As a temporary fix, you could see if you can buy a misting repair kit online, but the condensation will eventually occur again as the air gets in. The best thing to do is ask a window installer or glazier to replace the sealed unit for you.

It's simple to replace the glass in a window – the specialist will remove the beading around the window, remove the blown glass from your window frame and set it to one side. They will then clean up around the frame before adding spacers in, then fitting the new sealed unit into the frame. They’ll make sure it’s a snug fit before replacing the beading back around the window to secure it.

There's no reason to put off repairing a blown double glazed window since the cost is generally much less than replacing the entire thing. A sealed unit with installation costs an average of £100, whereas a completely new window will cost around £400. You’ll soon notice that it’s less draughty and will be able see out of your window once you’ve had the blown glass replaced.

On the grand scale of things there isn’t a huge difference between B-rated windows and A-rated windows. Consumer watchdog Which? have calculated an extra 6.5% would be saved on energy bills with A rather than B rated panes. Be aware that A rated windows are slightly more expensive, however.

Removing a double glazed window can be quite labour intensive. If you decide to try it yourself, make sure you give yourself plenty of time, and wear gloves and goggles.

Begin by unscrewing all opening windows at the hinges and removing them. Then take away the beading and putty around any fixed panes and take them out too.

Once you’ve removed all the glass, use a saw to put angled cuts in the frame, and a bar and hammer to remove it in sections. You should remove the sill if you’re going to replace that too.

Finally, cut through any screws holding the frame into place with a hacksaw.

• Climate - If your window faces south, it will be subject to direct sunlight for a lot of the day. This tends to cause the sealed unit to fail more quickly – a south-facing window may last between 10-25 years. This is because the spacer bars will twist as the temperature rises and causes the adhesive holding them together to eventually fail.
• Moisture - Windows in kitchens and bathrooms tend to fail more quickly because they come into contact with moisture more often. For example, if water gets on your windowsill when you shower, the seal around the glass will come loose more quickly if it’s constantly wet.

Yes, of course! It’s common for people to replace just one double glazed window. One reason that people want to replace one window is that the sealed unit inside has failed. You’ll know if this has happened because you’ll be able to see condensation on the inside of glass, which gets frustrating because you can’t wipe it away. In this case, you can choose to simply replace the sealed unit or the entire frame, which you might want to do if it’s looking past its best.

When you’re replacing just one double glazed window, if you know the brand of your current windows you could ask your installer if they can source the same ones. This will help to keep them looking as similar as possible, although if your existing windows are very old you may notice some discolouration on the exterior compared to the new one, and locks and trickle vents might look different.

Replacing just one double glazed window shouldn’t take a qualified window fitter long, and could cost as little as £400. If you want to simply replace the sealed unit, that may only cost around £250. You could try to fit a new window yourself, but it’s worth bearing in mind that all replacement windows need to be certified that they’ve been installed to meet building regulations, so you’ll need to apply to your local building control officer who will come and inspect the work then issue a certificate. If you ask an installer who is registered with a self-certification scheme (like FENSA) to fit the window for you, they can issue the certificate themselves when they’ve finished the work.

Double glazed windows are better than single glazed generally because they are more energy efficient. The clue’s in the name – double glazed windows have two panes of glass while single glazed windows only have one. In double glazed windows, there is a space between the two glass panes. This space is filled with inert gas or a tight vacuum, which helps to provide an extra level of insulation. That means that heat won’t escape your home easily, nor will it creep in, so you can keep your home at a more comfortable temperature.

The extra pane of glass also helps to increase your home’s security. Single glazing is pretty easy to smash through, whereas it will take much more effort to smash double glazing and will create more noise, so burglars might be put off.

Another reason why double glazed windows are better than single glazed ones is that they help to reduce noise. Of course, if you live by a busy road you’ll still hear some traffic noise, but it can be significantly reduced buy double glazing. In the same way that the inert gas in the middle of the two panes keeps heat in and the cold out, it also helps keep noise out.

With double glazing, you’ll also notice much less condensation. With single glazing, it’s common to see condensation on the inside of the windows, especially when the heating is on. This is because the outside of the window is cold, but the inside is warm. With double glazing, the insulation between the two panes stops there being such a difference in temperature between the inside and outside of the window.