What ho one and all,

Neighbour has gone on holiday and asked me to keep an eye on their house, including giving some liquid refreshment to some plants.

Looking up from the rear garden yesterday, this is what I see. Went to check from the balcony and the glazing is presumably, toughened glass but also laminated. It is only the inner pane that has fractured. Wheat could possible be the cause?

Toodle pip

The shattered pane looks to be leaning out a fraction. This could be as a result of the failure or it could be the cause of the failure.

If the glass was subjected to pressure from the inside then this could cause a failure of the inner sheet, especially if there was a (deepish) scratch on the inner surface. Otherwise an impact from a sharp object but this is difficult to imagine from the inside. If it was the outside pane I would suggest something like a stone thrown up from a lawn mower.

When you cut glass you score (or scratch) the surface then break the glass by bending to open the score mark - and the glass breaks along the score. If you try to break the glass by bending from the other side to the score then it won't break. You can't cut tempered glass 'cos it shatters as shown it the photo.

We had a bunch of similar looking panes shatter at the place I used to work. The cause was some manufacturing fault, I believe. How old is the balcony glass?

Gentlemen,

Thanks for the comments. The glass is only around one year old as the entire balcony was 'replaced / repaired' under the ten year warranty. the original, which looked the same, the glass was installed not according to the manufactures directions and water was draining into the timber from. This repair now has a steel beam sitting on top of the timber frame and the glass channel is bolted to that, away from the wall so any drainage issues are outside the timber frame.

Swung by a glass merchant today to ask (just because I am interested) and was told it is rare but does happen. Apparently, called Nickel Silicate Inclusion and is a manufacturing defect that is virtually impossible to detect. Just bad luck. But the glass manufacturers know and it is usually excluded from the t&cs as there is a remote chance of it happening.

In this case, guess it will be another insurance job.

Helped the guy take it to the garage this morning. Weighs 80 kgs. One step at a time with strops and vac device. I was sweating so much; better work-out then the gym!

Will not offer to help taking the replacement up-stairs as they are being paid for that. He now knows it is a two person job.

Agree with PiH, likely Nickel Sulphide Inclusion. Installed 100's m2 of toughened glass and the suppliers/experts always advised of approx 2% failure rate.

He needs to be careful what he tells the insurance company. One client (with completely no understanding of the failure reason), told the insurance company it had been very cold weather when the glass shattered She was refused her claim as they said weather events were not covered. I contacted the insurer to explain that the client had no experience upon which to make that assessment, and their reply was that in their experience the first report of a claim is always the most accurate, so they would close the case with the initial report. Best to say he has no idea how it happened, which is true.

Glad to see the installer used toughened laminated, as there's no handrail. Not all installers know the regulations. Think it's 17mm or 21mm thick for the glass sandwich IIRC, for a high level domestic balcony.