Johnson Window Films Dealer Resource Center

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Understanding Glass Breakage

In the Glazing Systems section of this site, we discussed thermal stress and how solar absorption can lead to glass breakage. We also touched on tensile stress where the weight of the glass can cause unwanted damage. There are several other glass breakage causes that dealers should be aware of:

Impact Stress

1. Impact Stress – caused by flying objects hitting the glass

2. Mechanical Flexing Stress – caused by heavy wind pressure

3. Twisting Stress – severe building movements as a result of earthquakes

Unfortunately, glass was not made to withstand these types of stress. When natural disasters such as earthquakes & hurricanes occur glass often breaks into dangerous shards endangering occupants and causing severe building damage. Additionally, man-made events such as accidental breakage, vandalism and terrorist bombings also will expose people to the dangerous effects of flying glass.

Many injuries are caused by accidental glass breakage.

Twisting Stress
Legislation for safer tempered glass did not take place until the mid-70’s. This means many buildings and homes are fitted with older, more dangerous glass. Building codes today mandate tempered glass for ceiling-to-floor windows or any glass located near doorways. However, all other windows in the home can be made of any type of glass (e.g. annealed). Similar requirements are found in the commercial building codes as well.

• Bomb Blast Test Results
• ISO GSA 4664
• ISO GSA 4667


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