Cracked Window
Discussion
Anybody experienced random cracked windows?
Double glazed window, one of three. Been in place several years. Had some Perfect Fit blinds added back in 2021.
Open the blind one day to find it cracked.
It's South facing and it was a sunny day. I put it down to the temperature change and the heat in the glass, especially with the closed blind reflecting back onto it. The blind fixing may put a little pressure on the glass and seems to have started from there.
Oh well, s
t happens. Had it replaced.
Two weeks later and open the blind to find this.
This time it seems to have cracked from the top middle, nowhere near the blind clips. I've been to order another replacement but mystified why its cracked again in such short time.
There are 3 panes in that room all with the same blind and no issues with those. Plus this is the 4th winter they've been through.
Any thoughts?
Double glazed window, one of three. Been in place several years. Had some Perfect Fit blinds added back in 2021.
Open the blind one day to find it cracked.
It's South facing and it was a sunny day. I put it down to the temperature change and the heat in the glass, especially with the closed blind reflecting back onto it. The blind fixing may put a little pressure on the glass and seems to have started from there.
Oh well, s
t happens. Had it replaced.Two weeks later and open the blind to find this.
This time it seems to have cracked from the top middle, nowhere near the blind clips. I've been to order another replacement but mystified why its cracked again in such short time.
There are 3 panes in that room all with the same blind and no issues with those. Plus this is the 4th winter they've been through.
Any thoughts?
Edited by Rick101 on Thursday 28th November 11:46
You could need a lintel above the window.
My folks had their wooden windows replaced with UPVC about 15 years ago and about two years ago, the brickwork above one of the windows was clearly 'sinking' down.
They were told it was common practice just to put bricks on top of wood frames as they were strong enough to support it. Then when you replace it with double glazing, suddenly the window can't support the weight.
The problem took more than ten years to manifest though, weirdly.
I don't know if this is the case in your situation, but perhaps something to investigate?
My folks had their wooden windows replaced with UPVC about 15 years ago and about two years ago, the brickwork above one of the windows was clearly 'sinking' down.
They were told it was common practice just to put bricks on top of wood frames as they were strong enough to support it. Then when you replace it with double glazing, suddenly the window can't support the weight.
The problem took more than ten years to manifest though, weirdly.
I don't know if this is the case in your situation, but perhaps something to investigate?
The pictures shows textbook stress fracture.
Annealed glass can crack with only 40c temperature difference across the pane, so blinds very close can cause thermal cracking, if they have the fastenings that’s push under the bead this makes the glazing a bit tighter than intended and even more prone to cracking. Those blinds can also cause pressure cracking especially in aluminium windows.
If it’s the same unit cracking each time I would bet that there is something shading it or it is getting heated or cooled by something, you often find it’s the one hidden by a tree, or the one that gets all the sun from behind nextdoors roof or whatever.
Replace with a toughened unit it is much more thermally stable up to about 250c and vastly more strong than annealed glass.
Annealed glass can crack with only 40c temperature difference across the pane, so blinds very close can cause thermal cracking, if they have the fastenings that’s push under the bead this makes the glazing a bit tighter than intended and even more prone to cracking. Those blinds can also cause pressure cracking especially in aluminium windows.
If it’s the same unit cracking each time I would bet that there is something shading it or it is getting heated or cooled by something, you often find it’s the one hidden by a tree, or the one that gets all the sun from behind nextdoors roof or whatever.
Replace with a toughened unit it is much more thermally stable up to about 250c and vastly more strong than annealed glass.
Sounds like it could be an issue. The blind, even when open concertinas at the top so there could be extra heat there.
It surprised me if I don't open them until midday (work nights) just how hot the interior glass gets.
The only question mark over it is that nothing has changed since 2021 when the blinds were fitted.
I'll speak to the supplier about toughened.
It surprised me if I don't open them until midday (work nights) just how hot the interior glass gets.
The only question mark over it is that nothing has changed since 2021 when the blinds were fitted.
I'll speak to the supplier about toughened.
Replacement due tomorrow morning, a toughened unit.
It will be interesting to see what the company think is the cause.
Some extra pics. I don't think It's the lintel as it's a tilt and turn window. The mechanism is free and easy. I can push closed with one finger with minimal resistance.
It will be interesting to see what the company think is the cause.
Some extra pics. I don't think It's the lintel as it's a tilt and turn window. The mechanism is free and easy. I can push closed with one finger with minimal resistance.
Edited by Rick101 on Wednesday 18th December 15:35
Well nothing obvious. Spacers in correctly, Maybe 3 mil gap between the glass and frame. Nothing protruding down. Everything lining up well.
Have replaced it with a toughened unit, replaced the perfect fit blind and left closed so it gets hot during the day. Hopefully no further issues.
Have replaced it with a toughened unit, replaced the perfect fit blind and left closed so it gets hot during the day. Hopefully no further issues.
Edited by Rick101 on Thursday 19th December 17:32
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