Find a Window Installer you can trust in Beckenham.

To install one small double glazed window, it will take anywhere between two hours and half a day. It will depend on whether one installer is fitting your window or two. And if you’re doing it yourself and don’t have any professional experience, it will take even longer.

When the window fitters arrive, they will make sure they’ve got safe access to the window and move any heavy furniture if they need to. Any good installer will lay down a dust sheet, but it’s a good idea to check that they’ve got one laid down before they start.

The first step any window installer will take is to double check the measurements of the new frame against your existing one. Hopefully it should match up, so then they’ll take the old window out. Then, they’ll insert the new frame into the aperture and bolt it into the concrete. They'll check it with a spirit level to ensure it’s even before moving onto the glass sealed unit.

The installer will place the glass into the aperture, then fit the beads to secure the glass in the frame. They’ll then use silicone and trim on the inside and outside to ensure the window looks perfect. You won’t be able to see where they’ve used sealants or trims because they’ll colour match them so it’s not noticeable. Then, they’ll tidy up all of their tools and the working area and let you know what needs to be done in terms of proving that the window meets building regulations. Most good installers are registered with a self-certification scheme, so will be able to issue a certification once the work is complete.

1. Using a rubber mallet and a strong pallet knife, remove the beading around the window. You might think they’re part of the frame, but they’re actually separate on the inside of the frame and can be taken out by using pallet knife to prize them out. Start with one of the longest beads first and leave the top bead until last.
2. Give the glass a little tap to loosen it if it doesn’t come out straight away, then the whole unit should slide out easily. Just make sure it falls towards you and not back out onto the ground below!
3. Clear any debris that has found its way into the frame with a brush. Add spacers at the bottom of the frame – these could be pieces of plastic.
4. Get your new sealed unit (make sure you measure the glass before you buy one so you know which size to get) and carefully take it out of the packaging. Look for the British Standard mark – that shows you the bottom of the glass.
5. Lift the glass into the frame, starting with the bottom first, and make sure that it fits square in the frame before taking the spacers out.
6. Use a little washing up liquid to spread along the beads to make it easier when you slide them back into the frame. If they simply push and clip back in, you can use something like a block of wood to help you push them in correctly. Put them back in reverse order to how you took them out.

Accidents happen, and sometimes windows get broken. And that will lead to you wanting to replace just the glass in your window, rather than the whole frame. Also, as windows get older they can mist up on the inside, which means that the unit has ‘blown’ - so you’ll also need to replace the glass. But how much is it to replace the glass in a window? Luckily, if the frame of your window is in good condition, there’s no need to replace it, and this will reduce the cost. For an installer to fit a new pane of glass in a single glazed window, the average cost is £100, while a replacement double glazed sealed unit will cost an average of £110. Of course, as this is an average, if your window is very large you may spend more, and if your window is very small the price may be less. That's why it’s important to get a range of quotes so you can compare costs and get the best price. If you’re good at DIY, you may feel confident enough to have a go at replacing the glass in your window yourself. In that case, the cost of sealed unit and any other materials you need will cost an average of £57. It’s a significant saving, and if you think you can do it, then give it a try. However, if you’re in any way unsure, it’s best to leave it to the professionals. A window installer will be able to replace the glass in your window in less than an hour. Even though it costs more for a professional to do it, if you get it wrong and have to start over it will cost you more in the long run.

• The glass has smashed from an impact such as a stone hitting it from a lawnmower
• You have been broken into and suspects used the window to gain entry
• The glass has blown (lost its airtightness) from constant water build-up around the seals, which is common in bathrooms
• Extreme weather or pressure changes have caused a crack

1. Including the beading (the plastic and rubber seals around the windows that can be removed), measure the width of the window frame.
2. Do the same for the height of the window, making sure you include the beading.
3. Then, take 10mm off each measurement, and you have the approximate size of your glass.

Some properties are unable to have double glazing, especially those in conservation areas or listed buildings. To counter this problem and still benefit from a warmer home and cheaper bills, secondary glazing is an option. Secondary glazing is a second pane fitted inside your original window. Secondary glazing will still save you around £105 yearly.

The energy efficiency of windows is measured using ratings, varying from A, the most efficient, to G, the least efficient. This scheme is run by the British Fenestration Council (BFRC). To comply with Building Regulations you’ll need windows of energy efficiency at least level C.

• Impact from a stone or other object smashing the glass in a ‘bullseye’ effect
• The result of a break-in
• Extreme weather or changes in pressure causing a crack
• The sealed unit being ‘blown’, meaning that it’s no longer energy efficient due to air leaking out

It depends on a few factors whether a new double glazed window will look different to existing ones. If your existing windows are very old, perhaps 10 years or more, then it’s likely that there will be some small differences.

The first thing to remember is that your double glazing is exposed to the elements as soon as it’s installed. So over time, unless you’re very good at cleaning and maintaining your windows, they’re likely to look a bit dirty. Window frames that are south-facing may also become slightly discoloured from the sun, so if you install a new window right next to it you might notice a difference.

Also, there have been lots of technical advances in windows over the years. If your existing windows are significantly older, you might notice a difference in the handles on openers, and if your existing windows were installed before 2010 they might not have trickle vents, which is an extra strip on the inside of your window to keep air flowing through your home. While it’s not a legal requirement for replacement windows to have trickle vents if the original one didn’t, it’s a good idea to have them installed as they help prevent condensation and mould.

The only truly noticeably different elements to a new double glazed window compared with existing ones are likely to be on the inside, which might not be a problem for you if you only have one window in a room. However, if you know the brand of your existing windows, you can ask your window installer if they can source the same ones. Even if they’ve been updated slightly, the difference should be minimal.