Question 1

How long do double glazed sealed units last?

Accepted Answer

When it comes to how long double glazed sealed units (the glass inside the window) last, a lot of it is down to the quality of the glass and the environment that your windows sit in. It’s not uncommon for your window frames themselves (especially if they are uPVC) to last longer than your sealed units. Sealed units are called that because they’re two panes of glass sealed together with an air gap in between. They use what’s called a ‘perimeter seal’ to protect the air gap between the panes, and is usually made of butyl mastic which retains a desiccant within a perforated metallic spacer bar. The desiccant’s job is to absorb any moisture which finds its way into the air gap to stop your window from misting up on the inside. When a sealed unit fails, or is ‘blown’, it’s usually because moisture builds up around the seal and causes it to fail. Sealed units won’t last forever, so you will eventually end up with condensation inside the panes of your double glazing, but in an ideal environment your double glazed sealed units could last up to 30 years, with some manufacturers claiming as long as 40 years. But they do require a bit of maintenance and the position of your windows will also make a difference as to how long they last. There are a few things that determine how long a sealed unit will last: 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. When you replace the sealed units in your windows or get completely new double glazing, make sure you choose an installer that uses quality products and will take all the steps to ensure that your sealed units are kept away from moisture as much as possible.

Question 2

How to replace the glass in a uPVC window?

Accepted Answer

It’s not too difficult to replace the glass in a uPVC window, so if you’re a confident DIYer you could have a go at this yourself. We’ll go through the main steps on how to replace the sealed unit in a uPVC double glazed window: 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. 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! 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. 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. 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. 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. And there you go! If you’re feeling confident you can have a go at replacing the glass in your uPVC window yourself. But if you’ve got any worries, leave it to a window installer who will be able to do it in less than an hour.

Question 3

How much is it to repair the glass in a window?

Accepted Answer

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.

Question 4

Can the glass in a double glazed window be replaced?

Accepted Answer

Yes, the glass in a double glazed window can be replaced. The glass in a window, or sealed unit to use its proper name, is not permanently attached to your window frames so if it gets damaged but your frames are still intact, there’s no need to replace the whole window. The glass in your double glazed window might need to be replaced due to: 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 A lot of window installers will replace the glass in your double glazing for you, but you might need to get quotes from specialist glaziers too. Glaziers deal purely with the glass in windows rather than installing entire frames. It won’t take a professional very long to replace the glass in your window. They will remove the beading from around the window with a pallet knife or chisel, leaving the top one until last to keep the sealed unit stable. Then, they simply lift out the glass carefully and will discuss with you whether the removal of the old sealed unit is included in their quote. Next, they will brush away any dust and debris that’s made its way into the frame and place spacers at the bottom. They will then lift the new glass into the frame, making sure it’s completely square. When they’re happy, they’ll remove the spacers and replace the beading back in reverse order. You’ll notice the replacement glass in your new window straight away as draughts should be eliminated and you’ll be able to see clearly again!

Avg. price low	Avg. price low £57
Avg. price	Avg. price £75
Avg. price high	Avg. price high £87

	Labour cost	£53
	Material cost	£19
	Waste removal	£4

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