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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.

• Washing up liquid
• Glass cleaner
• A lint-free cloth or rag
• A putty knife
• A paper plate
• Acetone

Whether you need toughened glass in your windows depends on where the windows are in your home or business. Toughened glass is sometimes referred to as tempered or safety glass, and it just means it’s stronger than the standard glass that’s usually offered with double glazed windows. So how do you know if you need it?

Toughened glass is useful in areas of your home where you might come into contact with the windows if you were to trip and fall. If you put your hands out to steady yourself on standard glass the chances are it would break into large sharp pieces with jagged edges. Of course, this means that you could seriously cut yourself if this were to happen. With toughened glass, the structure of the glass is changed so that if it breaks it shatters into lots of tiny pieces, minimising the risk to you if you were to fall on it.

You might want to use toughened glass in patio doors, low windows or frames next to doors. It just means that you will be safer if the unlikely happens and you or a family member falls through the glass. There are certain requirements through Building Regulations with windows at a certain level, but any reputable window installer should be able to go through these with you if you need to replace your windows with toughened glass. The regulations will only apply to new windows – there's no need to switch your windows to toughened glass early, but when you do come to replace them you’ll need to make sure they meet the standard.

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.

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.

• Thick gloves
• A hammer
• A broom
• A vacuum cleaner
• Thick-soled shoes
• Safety goggles

1. Put your gloves on and use the hammer to remove the rest of the glass. Make sure you hit the glass away from you.
2. Using the broom, sweep away any loose glass from the area, making sure you do both inside and outside.
3. Use your vacuum cleaner to remove any small pieces of glass that you might not have been able to see.

Unfortunately, you can’t fix the glass on one side of a double glazed window. That’s because they’re sealed units – once one pane of glass is broken, that will break the seal and its thermal insulation properties will be lost.

The good news is that if your window frame is still looking great, there’s no need to replace that. You can simply replace the glass in the window, which will cost much less. You can look to spend around £250 on a sealed unit, whereas a whole replacement single window may cost up to £600.

When an installer comes to replace the glass in your double glazed window, they will survey the inside and outside of your home around the window, then move any furniture by the window so they’ve got access. They should then pop a dust sheet down to stop any debris from getting on your floor.

Then, the installer will carefully remove the beads from the frame. They will then lift the glass out of the frame and put it somewhere safe before cleaning out all of the dust and any debris that has found its way into the frame. Using spacers at the bottom of the frame, the installer will make sure that the sealed unit is square in the frame to get a good fit. Once they’re happy, they will replace the beading and make sure it looks perfect before cleaning up their tools.

You could have a go at replacing the glass on a double glazed window yourself, but it’s not recommended. Leave it to the professionals who will know exactly what to do and will be able to do it quickly and safely.