Glass has always been a desired material, maybe the fact that it is a substance searching for its identity, not knowing if it is a liquid or a solid, has kept us entranced and obsessed with trying to understand and create ways to have it in our lives on a daily basis. Maybe it’s our personal challenge, to see how long we can keep such a brittle substance in our presence without breaking it that spurs us to build 21st century “castles” made of glass. Who knows, but the fact is, we are surrounded by glass daily. It's part of our lives, and we all know that once it becomes part of our business or jobs, there is just no “breaking” away.
Two of the ways we think about glass are somewhat contrary. The first is the beautiful clean substance that skins a building in a curtain; the transparent barrier between the outside and inside world. The second is as a broken and shattered mess that can be dangerous and should be avoided.
In 1903, a beaker containing some cellulose nitrate fell from a bench top and broke. Amazingly, the glass didn’t go flying across the floor because unbeknownst to the chemist, he had just invented laminated glass.
Much has changed for laminated glass since that first day of discovery. The interlayer no longer turns a delicious chocolate brown upon exposure to the sun, the views through the glazing no longer look like a fun house mirror, and the invisible interlayer between the glass can now protect from the tirades of an angry Mother Nature and some of the malevolent acts initiated by our fellow beings. Amazingly, modern laminated glass provides incredible clarity and protection with an interlayer made from a specially designed polymer material that is between one and three credit cards thick.
Although it doesn’t stop glass from breaking, laminated glass continues to find its way into new applications for areas that require control of the shattered particles, fragments and shards should the glazing be broken. These are not necessarily areas that are listed as hazardous glazing locations in Chapter 24 of the International Building Code, but they are areas where immediate replacement, fall-through potential, or hazards to pedestrians passing near or below, are of concern.
In some cases, insulating glass units that have one lite of laminated glass are being flipped from the traditional orientation to put the laminated glass outboard in order to retain broken glass from falling during storms or seismic events. This construction, in this orientation, will put the non-laminated lite toward the interior and depending upon the mode of breakage, potentially causing concern for the occupant versus the assailant. As the specification for shard retention spreads, so does the use of double laminated glazing units in facades. The configuration is typically asymmetrical with the outboard lite being a non-safety laminated lite for shard retention purposes only, and the inner lite being the traditional laminated lite in a configuration capable of meeting the safety, sound, hurricane or blast resistant specifications.
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