We had double-glazed sliding patio doors installed about 18 months ago. On separate occasions over the past couple of months, two of them have spontaneously shattered from around the centre of the pane. Both of them inside panes which rules out unknown impacts from outside.

enter image description here

The first one was in the bedroom; I had just gone to bed and could hear what I thought was rain or sleet against the window. I thought that odd as it was a perfectly clear sky just before I went to bed. I opened the blind and the whole inside window had shattered. It was still in-situ (thankfully!). The installer is currently in the process of trying to get this one replaced under warranty from the manufacturers. But when the 2nd window shattered he said he'd have tremendous trouble trying to convince the manufacturer of two separate faults.

He went on to say that if it was a manufacturing or installation fault, then the glass cracks/shatters from around the edge of the glass. But these are near enough bang in the middle (excuse the pun!). At no point have they been hit with anything. Indeed, the installer said that these units are incredibly strong, and that they have trouble breaking them in the skip, especially when trying to break them from the middle on the pane.

I read online about this and how that it could be caused by Nickel Sulfide contaminants during the manufacturing process; these contaminants expand with variations in temperature and it's the expansion that causes the glass to shatter. That explanation certainly fits with both of my scenarios; the 1st occurrence was at the end of summer; it was a very hot day, but the temperature plummeted in the evening and it was the first night that we had a frost. The 2nd occurrence happened recently (in the middle of winter here in the UK); it had been about -3c for a couple of days and the wood burner had been on almost all the time. That window shattered over-night.

The glazier that installed them says he has never heard of such things happening, but another glazier I spoke to said that it's not uncommon, especially with large variations in temperatures.

Has this happened to you? Do you know what caused it?

  • 4
    But when the 2nd window shattered he said he'd have tremendous trouble trying to convince the manufacturer of two separate faults. Actually, 1 is a fluke that can be manufacturing defect or mishandling or whatever. 2 is much more likely to be a manufacturing defect - i.e., a whole batch bad - so the manufacturer will likely be quite interested in the situation (even if they don't want to pay up). Unless you live next to batting cages. Jan 19, 2021 at 15:23
  • 3
    Just wondering if manufacturing or installation defect. If they were installed in place too tight, expansion might have cause it also, but it would be much less likely than a manufacturing defect or physical damage(being hit). Would also google the manufacturer plus shattering glass, to see if there are other reports.
    – crip659
    Jan 19, 2021 at 15:33
  • 3
    It looks like an impact broke the glass. There are fracture lines radiating out from a single point. Perhaps a near-sighted large bird flew into it or baseball or some other object struck it. Jan 19, 2021 at 15:58
  • 1
    Good point @manassehkatz-Moving2Codidact re. more likely a manufacturing fault.
    – Steve Dunn
    Jan 19, 2021 at 16:01
  • 3
    I have seen quite a few outside ones shatter birds and rocks, the only one I have seen inside was from an air soft (plastic pellet) gun. The owners were claiming it was improperly installed I was wondering what the little green balls were. Then I saw the kids in the back yard playing with those guns. The owner swore the kids never used them inside and they were safe, inside is where I first saw the BB’s made of plastic. I had an old window on the truck I asked the boy to shoot it and it did break the window at ~10’, 3 meters. The boys confessed after being questioned. Defects 2 in 1 home ???
    – Ed Beal
    Jan 19, 2021 at 16:53

1 Answer 1


I'm 95% confident that, in this case, it was nickel sulfide contaminant. I took photos of the epicenter of the shatter and zoomed in on the computer. The contaminant is pretty clear to see: enter image description here

This is pretty much exactly what articles like these show: https://www.constructionspecifier.com/fully-tempered-glass-and-spontaneous-fracture/2/

Not the answer you're looking for? Browse other questions tagged or ask your own question.