The nature of tempered glass is that it breaks based on a point impact and shatters in tiny pieces which are less likely to cause injury. However, while the surface of tempered glass is highly resistant to impact spread over the face of the panel, the edges of the glass are more sensitive to impact and subsequent failure. Keep exposed edges to a minimum.Tempered glass may also have a delayed reaction with breakage occurring some time after the incident which causes the actual failure such that it becomes impossible to determine the actual cause and effect.
Another concern is a built-in hazard which is inherent in some batches of tempered glass — the presence of an invisible seed or pellet known as nickel-sulfide. This seed is believed to be present in 1 out of 10,000 lites of tempered glass. This seed grows steadily until it causes sudden and total destruction of the glass.
Another issue, with laminated glass panels in particular, is related to the choice of grout that is used. The use of Portland based grout in the presence of moisture causes an adverse reaction with the aluminum shoe.