Double glazed unit blown

29 Dec 2017
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United Kingdom
Hi guys,

I try to take on some jobs myself rather than paying for them and would like to know if it's worth trying to replace a sealed double glazed unit myself.

I can measure the width and height by measuring from edge of the beading and minusing 10mm. ( So I've read)

Can I make the assumption that the glass is 4mm, internal and external?

Do I need to remove the unit to measure the total depth of the unit?

It has the old beading where it can be removed from the inside and outside.

I have attached photos.

I have been quoted between £80 and £100 but can see units being sold online for around £25.

Any advice would be appreciated.

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Thats a 28mm unit i.e 2 panes @ 4mm and a 20mm aluminium or c rated spacer or 4/20/4

Your window is externally beaded/glazed so with a scraper prize out the black gasket called wedge from the inside, go outside, the unit should now be loose, push the unit inwards and remove the beads. Before removing the glass make a visual note of how the glass is packed when the beads are removed, its an opener so it'll be toe and heeled, its not life or death but it will help the window close better if its repacked the same, thats assuming the replacement unit is made the exact same size as the old
Thanks for your help.

So remove the white beading on the inside first and then remove the black gasket.

Sounds easy.

Does the black gasket just all go back on? Is there any security tape or foam involved?

The view from the outside is identical. White beading and a black rubber seal.

Also is it safe to measure the width and height by the edge of the beading minus 10mm?

There is no white beading inside. Its the black gasket inside you need to remove on the inside, the rest of the job is outside. Measure bead line and deduct 10mm width and height, do not measure from inside, that IS NOT a bead line
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Excellent advice thanks. I have just measured the inside ha ha.

So I just scrape out the black seal part.

When I put the new unit in does it come with a new gasket?
Use a flat wallpaper type scraper, push it in under the rubber gasket between the frame and gasket not the glass and gasket and just lever it out, I would imagine its just one piece of gasket with the corners snipped to allow it to fold in the corners so they'll be a begining and end point in one of the corners, if you can find it start there otherwise either side in the middle of the long lengths. Re use your old gasket, it is specific to the frame, the glass unit is just that
Thanks very much I will order one.

I was going to order one online. Hopefully that is safe. Should the glass be toughened?

I'll post back once I've either completed it well or messed it up!
That will need to be toughened glass.
Can you post a link to your online suppliers, I have some to do ?
Should the glass be toughened? That depends if its in the 'critical location' i.e. is the glass closer to the ground than 800mm in or out, is the 'blown pane' within 300mm of a door? If its neither then it doesn't need to be toughened, check your old unit though for a kite mark in one of the corners, from your pictures i can't see any so that suggests its ordinary float glass
Apologies. Thought it was a door, not a window. Need new glasses.

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