Spontaneous glass breakage explained

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Spontaneous glass breakage explained

Spontaneous glass breakage is a rare but possible event that cannot be predicted. Faisal Husain, Chief Executive of DGCOS, explains what it is and how their installers handle it when it happens.

It is a phenomenon that all door and window installers are aware of, but hopefully very rarely happens: Spontaneous glass breakage, where a pane of glass seemingly shatters for no discernible reason. Clearly, this has implications for any glass installation, particularly those in high-rise or public settings where the risk of injury is high. However, it can also happen in a domestic setting, and most consumers are not even aware it is a possibility.

Recently, DGCOS conducted a survey of some of our installer members to find out their experiences of spontaneous glass breakage, and how they handle it if it happens. Firstly, though, what causes it and how can the risks be reduced?

What causes spontaneous glass breakage?

When a glass pane shatters, sometimes years after installation, and without obvious impact damage, it is probably a case of spontaneous glass breakage. This has two main causes, although other factors such as fitting and glass edge quality can also be contributing factors. The most well-known is thermal shock. This is where the edges of a tempered pane of glass expand and contract at a different rate to the centre, causing uneven distribution of stresses within the pane. Once those stresses exceed the strength of the glass, the pane can shatter.

The other cause is nickel sulphide inclusions that can occur during the manufacturing process which can lead to a failure, again a long time after installation. Tiny particles from the production process can form into what are known as stones inside the glass. During manufacturing, they contract but, after installation, they can try to expand again, and if this happens over a period of time, spontaneous glass breakage can occur.

The risks can only be minimised by using toughened glass, which is five times stronger than tempered glass and which reduces the risk of thermal shock. Alternatively heat-soaked glass, which is put through a controlled heating and cooling process that puts the edges, surface and centre of the glass in tension. This is an extra step in the manufacturing process, which makes this kind of glass expensive, but it can often be used in hard to reach places or in decorative glass that may be more costly and harder to replace.

What do installers say?

Spontaneous glass breakage doesn’t happen often, but because it is unpredictable and there may be other hard-to-determine contributing factors such as poor edge fitting or quality, it is not usually something that glass manufacturers cover under warranty. Most installers will not cover it either, although among the installers that we spoke to have a policy in place to help a customer should they find themselves in this situation. Consumers will often discover that the terms and conditions they sign will exclude any costs associated with spontaneous glass breakage but our advice for any homeowner is to speak to the installation company and see what they can do.

Some installers will explain the risks in advance, although most installers do not do this as it is such a rare event. Most will ensure quality of finish and edge work to minimise the risk but, in our survey, most deal with it on a case by case basis and will do what they can to help the customer. As one of our installers says, “It’s never the customer’s fault.”

Reaching an agreement

In the spirit of good customer service and word of mouth recommendations, it is in the long-term interest of an installer to work with the homeowner to fix the affected glass pane. The installer is under no obligation to contribute to the cost, but we found that the installers we spoke to are flexible in their approach, whether the labour is paid for by the installation company, or the replacement glass provided free of charge. Unfortunately, it is usually only when breakage happens, is the consumer aware that it is even a possibility.

For installers who are not fully aware of the specifics of spontaneous glass breakage, DGCOS offers advice for members, in addition to the vast range of benefits of being an accredited DGCOS installer.

Attribution for image: Image by mrsiraphol on Freepik

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