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 measure the glass for a window replacement?

Accepted Answer

If the glass in your window has been damaged, you might only need to replace that rather than your whole window frame. Common reasons for needing to replace the glass in your window include: 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 If your frames are still intact and there’s nothing wrong with your window’s locks or trims, there’s no reason why you can’t just replace the sealed unit in your window. To help with the quotation process, a window installer may ask you to measure the glass for your window replacement. It’s pretty simple to just measure the sealed unit inside your window. There are just 3 steps you need to take: Including the beading (the plastic and rubber seals around the windows that can be removed), measure the width of the window frame. Do the same for the height of the window, making sure you include the beading. Then, take 10mm off each measurement, and you have the approximate size of your glass. A reputable window installer will still make their own measurements before confirming the size of the glass in your window and going ahead and ordering the replacement. Make sure you get a range of quotes from local and national installers so you can compare the price and their quotation process.

Question 3

Can you repair blown double glazed windows?

Accepted Answer

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.

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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