Why Spontaneous Glass Breakage Occurs And How To Prevent It

What is spontaneous glass breakage

Can a glass door shatter by itself? It sure can!.

Over the years, we’ve received emergency glass replacement calls from shocked homeowners who have reported a strange, frightening, and potentially dangerous issue: door glass that appears to “explode” spontaneously into small pieces for no apparent reason.
In many cases, it occurs in the middle of the night, jolting the homeowners awake as a door glass panel bursts and then crashes to the floor. This phenomenon is isolated to toughened glass which is commonly used in Australia for shower screens and sliding doors.

Despite the fact that toughened glass is four or five times tougher than normal glass, accidental glass breakage does occur on occasion.
While this is a rare occurrence, we figured we’d teach you a little bit more about what it is, why it occurs, and what you can do to might the odds of it occuring.


The following are the most common causes:

Installation Issues

Glaziers can easily nick or chip the edges of the glass with various tools while moving and installing it.
These minor nicks or chips may not cause immediate breakage.
However, as the glass expands and contracts over time, stress concentrations can form around the nick, leading to breakage.
When tempered glass breaks, the entire unit usually shatter.

Thermal strain

Thermal stress is another possible cause of spontaneous glass breakage.
Thermally induced stresses in glass are caused by a positive temperature difference between the centre and the edge of a glass lite, indicating that the former is hotter than the latter.
The expansion of the heated glass centre causes tensile stress at the glass’s edge.
Breakage occurs when thermally induced stress exceeds the edge strength of the glass.

Manufacturing Defects

Inclusions of nickel sulphide may be found in the glass.
The use of stainless-steel machinery in the glassmaking and handling process is the most common cause of these inclusions.
Small stainless steel shavings containing nickel change structure and grow over time, causing internal stresses in the glass.
Tempered glass is almost always prone to this type of breakage.

How to prevent spontaneous glass breakage?

Use a qualified glazier for your door glass replacement who has worked with toughened glass before, and use glass that meets Australian Standard 2208:1996.

Imported glass may or may not meet Australian Standards, but it is becoming more popular because it is often a less expensive alternative to toughened glass made in Australia.
Look for the stamped Australian standards logo on the glass panel’s corner.

Video of spontaneous glass breakage for one of our customers in Sydney –

About the Author
Marc Gombi

Marc Gombi

Marc is an experienced glazier providing high quality glass replacement and repair in Sydney Lower North Shore.

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