Glass plays a vital role in modern architecture, offering aesthetics, light, and a sense of openness. However, when it comes to safety, the term “safety glass” can lead to a false sense of security or false expectations. While designed to mitigate specific risks, current safety glass standards don’t address all potential hazards, leaving gaps in public protection. This article delves into the nuances of safety glass, exploring its current definitions, limitations, and the urgent need for an expanded understanding of glass safety.
Understanding Current Safety Glass Standards: A Historical Perspective
Since the late 1960s, organizations like ANSI (American National Standards Institute) and CPSC (Consumer Product Safety Commission) have diligently worked to establish safety glass standards. Their primary objective has been to reduce the risk of death and severe lacerations in the event of accidental impact and breakage.
This focus emerged from numerous incidents where individuals walked through glass door lites or sidelites or slipped and fell against shower enclosures, leading to severe injuries and fatalities.
The core of these safety glazing standards, specifically ANSI Z97.1 and CPSC 16 CFR 1201, revolves around two key products which each have their own safety strategies:
Tempered Safety Glass: This type of glass undergoes a process of extreme heating and rapid cooling, which significantly increases its strength. When broken, tempered glass shatters into hundreds of small cubes, significantly reducing the risk of deep cuts and severe lacerations.
Laminated Safety Glass: This glass consists of two or more panes of glass bonded together by a strong, transparent interlayer, typically made of polyvinyl butyral (PVB). If the glass breaks, the interlayer holds the fragments in place, preventing them from scattering, thereby minimizing the risk of injury.
Tempered and laminated glass are equally acceptable when the sole requirement is adherence to safety glazing standards. However, this interchangeability overlooks crucial differences in their behavior when compromised. The differences between tempered and laminated glass can have significant safety implications beyond laceration mitigation.
The Unforeseen Hazards: Beyond Lacerations
While effective at reducing the seriousness of lacerations, current safety glass definitions fall short in addressing another related safety concerns: The situation in which an unfortunate person breaks through glass and then falls through the window from heights. Examples include floor-to-ceiling windows and glass handrails.
The Perils of Tempered Glass in Elevated Applications
Imagine a scenario where a tempered glass handrail spontaneously breaks, which can occur even without direct impact due to internal stresses or minor imperfections. If this happens on an upper floor, hundreds of small glass cubes, thought-of as “safe,” can be propelled outwards by wind. While individual pieces may seem harmless, a shower of glass cubes onto a pedestrian below poses a significant risk. These small pieces can cause eye injuries.
What if the cubes cling together in sizeable clumps with jagged edges, impacting someone from above? The risk of impact injuries, accompanied by deep laceration, becomes a genuine concern. Furthermore, if a section of a tempered glass handrail completely disengages and falls, it creates an open void. A child, unaware of the missing barrier, could easily fall through. This tragic scenario is exemplified by the death of Eric Clapton’s son, Conor, who fell through an open window.
The Challenges of Laminated Glass in Elevated Applications
Laminated glass, with its ability to hold together when broken, is inherently safer in an elevated setting, but it must stay in the frame in order to be safe. If not, it becomes a menace. If the broken pane remains securely affixed within its frame, the fall barrier is maintained. However, if the laminated glass is not adequately secured, the entire broken pane can detach, take flight, and sail like a flying carpet. Critical injury or death can befall the unsuspecting pedestrian who is in the way.
The tragic death of Anna Flores in Chicago in 1999, fatally struck by a large piece of wind-blown glass, serves as a shocking reminder of this potential danger.
If the handrail glass evacuates the frame, it then becomes an invisible hazard. People on the balcony may be unaware of the missing safety barrier and inadvertently fall through.
What “Safety Glass” Doesn’t Guarantee
It’s crucial to understand what current “safety glass” is not designed to do:
Prevent Falling Through: Neither tempered nor laminated glass, under current standards, is explicitly designed to prevent an individual from falling through the glass when broken. Whereas tempered glass is 4-5 times stronger than annealed glass in resisting uniform loads, which may reduce the chance of initial breakage, it doesn’t guarantee that the glass will be a fall barrier.
Prevent Broken Glass from Falling Out: Current standards do not ensure that broken glass, whether tempered fragments or a compromised laminated pane, will remain within its frame, preventing it from falling onto people below. While laminated glass is more likely to stay in the opening even when broken, there’s no guarantee, as this isn’t a design requirement within the current “safety glass” definition.
Kudos to the Eataly Restaurant on Ohio Street in downtown Chicago. Glass handrail is laminated safety glass, not tempered. If someone breaks this glass, the glass will still be a barrier preventing a fall.
The Imperative for an Expanded Definition of “Safety Glass”
The current definition of “safety glass,” primarily focused on reducing lacerations, is increasingly obsolete in the context of modern architectural design and the diverse ways glass is used. We need to move towards a broader, more comprehensive concept of glass safety.
This expanded definition should encompass:
Protection Against All Injury Types: Beyond lacerations, the new definition must address risks of impact injuries from falling glass and the danger of falling through compromised glass barriers.
Containment of Broken Glass: A critical component of proper safety is ensuring that even if glass breaks, it remains contained within its frame, preventing it from falling and injuring people below.
Maintaining a Safety Barrier: The glass, even if broken, should continue to function as a safety barrier, preventing falls or unintended passage, particularly in applications like handrails and floor-to-ceiling window applications.
The Bottom Line
While significant progress has been made in making glass safer, the evolving nature of architectural design and the potential for new hazards necessitate a re-evaluation of what “safety glass” truly means. By embracing a broader definition that prioritizes not only the reduction of lacerations but also protection from falls and falling debris, we can ensure that glass, a material of immense beauty and utility, truly lives up to its promise of enhancing safety in our built environment.
Contact us if you need help with safety glass or if you have a problem with glass that is unsafe.
Congratulations to Susan Koeppen and the KDKA production team for an excellent piece on glass safety. See it here and be sure to watch the video:
How Safe Is The Glass Used In Doors And Window?
This article is very informative but it makes me ask – “what is the solution?”. Is the answer to stop specifying floor to ceiling glass and glass balcony guards? I have heard of a new laminated glass product that is starting to be used for guardrails. Here the lamination holds the glass in place and does not behave like a wet blanket. But how do you handle floor to ceiling glass in a window?
If you have an existing structure with this problem a 3M security / safety film with a wet glaze or mechanical attachment system would be a cost effective solution.
Typical applications for bent laminated glass include railing systems, elevator and revolving door enclosures, skylight and overhead glazing, and interior partitions. In addition to minimizing risk of injury from broken glass fragments, bent laminated glass is effective in security areas, reduces sound transmission, blocks potentially harmful ultra-violet light rays, and is available in a range of color tints.
In the event of safety laminated glass breaking, it is held in place by the interlayer of transparent plastic. These intermediate layers keeps glass bonded even when broken, and its high strength prevents the glass from breaking up into large sharp pieces.
The association just installed all glass balconies. They refuse to tell me if it is ok to actually go out on mine as of yet. They are literally avoiding my calls and messages. The originally sealed balcony door has since been opened which led me to think I could go out. I notice that there are openings between glass squares, not on all of them…just a few? They are about an inch wide. Is this normal? How can I tell if my balcony is safe and ready for use?
Gaps in the railing glass under 4″ are sometimes designed into the product but to know if your specific railings are ready for prime time requires the OK of a professional who understands these things.
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Awesome article on glass safety. A very important point that you mention, “even though the glass is laminated the glass glazing should be it properly done to avoid accidents.”
Hi, I liked your article. I have four french doors that have Low E Tempered Safety Glass. I also have an appointment to have #M security film put on the doors to help in case of attempted robberies. Do I need both? Thanks!
My wife and I have been thinking of installing tempered glass in our home. I did not know that the tempered glass was safer than the regular glass because it breaks in smaller pieces. We want to make sure our house is as safe as possible while still looking good and tempered glass helps with that.