Safety Glass 101

I inspected a duplex last week that had glass sliding doors. The doors were in poor condition, but I was more concerned that they did not contain safety glass. Safety glass is designed to minimize physical damage in case of glass breakage. Safety glass must contain an identifying label that can not be removed (acid-etched, sand blasted etc). Safety glass is usually laminated or tempered. 

 

Laminated glass is two layers of glass sandwiched with a laminate. The laminate is the reason why the pieces are held together when it is broken. 

Sometimes you can identify unlabeled laminate glass by examining the reflection of your hand or some other object- you should see two different images.



Tempered glass is almost 5 to 10 times stronger when compared to its untempered counterpart. Tempered glass shatters into tiny fragments with rounded edges when it’s broken. It can take a higher load and deflects further before breaking, but can not be reworked.

Tempered glass can also be identified through polarized glasses when viewed from an angle. Black lines, a result of the heating and cooling process, should appear as your angle from the glass surface increases when you approach the glass’s side.

However, when uncertain, and in potential hazardous areas, I always assume that glass is not safety glass and recommend further assessment.

If you are interested in more information on when safety glass is required, here is a link to the International Residential Code R308.4

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