Schools shift gears as new building codes "expel" wired glass
By Jerry Razwick
Many different building components have a part to play in the defense against fire damage. Smoke alarms help detect fire at the earliest stages. Extinguishers offer a way to douse small fires. Sprinklers can be placed strategically to suppress any bigger flames that appear. But the important job of containing a fire to a limited area is carried out by one of the least noticeable fire fighters of all: Glass.
Wired glass is almost as common in schools as dry erase boards. You see it in classroom doors, administration windows and corridor lites. Whenever codes have dictated the use of fire-rated glazing, wired glass has been the predominant choice. It has been a reliable, economical solution in the promotion of life safety.
So it undoubtedly came as a surprise to some when the International Building Code (IBC, section 2406) adopted new standards that eliminate the use of traditional wired glass in K-12 schools, daycare centers and athletic facilities. How could such a popular product fall out of favor so quickly and completely?
The answer lies not in how wired glass responds to fire, but how it responds to human impact. Contrary to public perception, wired glass is not "break-proof." The wires are often misinterpreted as adding a level of security, when in fact they are only there to hold the glass in place during a fire. Actually, wired glass breaks quite easily, and the wires can cause significant injuries when the glass is broken, since they form dangerous snags.
That's bad news for a school corridor full of active students, running and jostling each other on the way to class. Glass in that setting is likely to encounter a great deal of physical contact. On a day-to-day basis, there's a much greater risk of breakage due to human impact than fire. If wired glass is being used, the threat of serious injury increases.
For a long time, wired glass was the only fire-rated glazing material on the market. No other glass could endure the intense heat of a fire without vacating the opening. So architects and school officials had to choose: Should they offer fire or impact protection? Since nothing was available that could meet both types of code requirements, the CPSC gave wired glass a special exemption from impact safety standards. Fire safety was considered the more pressing need.
But times changed. Newer, "wireless" glass products became available that could withstand both fire and impact, thereby eliminating the need for compromise. Although they look like typical window glass when installed, these products are the result of much more advanced technology, giving them capabilities far beyond traditional glass.
In addition to new glass options arising, statistical evidence regarding wired glass-related injuries began to mount. As the new IBC was being formed, a special Ad Hoc Committee reviewed the data related to wired glass injuries. They discovered that the majority of incidents occurred in schools or athletic facilities.
The media picked up the story and informed the general public of the situation. One parent (of a student who suffered permanent nerve damage from broken wired glass) spearheaded a grassroots campaign to have the exemption removed.
The committee recommended curtailing the CPSC exemption, and the International Code Council (ICC) voted to act on their recommendation. All glass in "hazardous locations" of schools and athletic facilities will now be required to offer high impact safety. The exemption will still stand for other commercial facilities, although there is an effort being lobbied to remove that exemption as well.
Several years ago, such a code change would have been impossible to satisfy. But today, there are many glass products on the market that are suitable substitutes for wired glass. Many of them far surpass wired glass in their ability to withstand fire and impact. What's more, because these products are wireless, they offer aesthetic advantages as well.
Technically, one alternative to wired glass isn't glass at all: it's ceramic. Thanks to art class kilns, even most school children are familiar with ceramic's ability to withstand heat. That is why ceramic has become a favorite material for use in such "hot spots" as cook tops and high performance car engines. Fire-rated glass ceramic offers the heat resistance of everyday ceramic with an appearance similar to clear window glass. With a very low expansion coefficient, glass ceramic has been able to earn fire ratings up to 3 hours. Laminated ceramics also provide high impact safety and can typically be specified in much larger sizes than wired glass.
One of the advantages of these products is that, like wired glass, they can be cut in the field. Tempered glass and other wireless fire-rated glazing materials usually do not have that flexibility. School districts that have been accustomed to stocking wired glass can now stock fire-rated glass ceramic in similar fashion, easing the transition away from the low impact wired glass.
Ceramics are not the only newer option to wired glass. Another category of glazing now on the market could be classified as glass fire walls. These multi-layer units resemble bullet resistant glass from the edge, and they offer fire ratings up to 2 hours. Tested to the same standards as solid barrier walls, glass fire walls block heat in addition to flames and smoke. As a result, architects can now specify unrestricted amounts of glass where ordinarily they would need to restrict glass to less than 25% of the wall area. Full lite doors with ratings up to 90 minutes are now a reality.
Glass fire walls are also now available with bullet resistance and security ratings. This is a real breakthrough, since most security glass contains highly flammable plastics, which can seriously hinder efforts to contain a fire. Having a single product that can provide protection from fire, impact and bullets gives schools another tool for creating a safer learning environment.
Code officials have noticed that some contractors have begun attempting to overcome the drawbacks of wired glass by applying a safety film to it in the field. However, such a solution has its own problems, since most films are also plastic and highly flammable. The fire rating of the glass could be nullified in the effort to provide impact safety. Unless a film product has been successfully tested for both impact and fire safety with wired glass, at an independent laboratory such as UL, it should not be applied in a fire-rated location. At least one wired glass manufacturer has issued a memo indicating they will not stand behind the fire rating of their product if someone applies a film to it after it leaves the factory.
Fire-rated glass with surface applied film is appropriate for many commercial applications, but schools are much more susceptible to abuse than other types of facilities. Even the toughest films can be marred, peeled or damaged by a determined vandal. Students who discover a corner to the film may pick at it and separate it from the glass. When the film is damaged, it is not only unsightly -- it potentially can impair the performance ability of the product and render the fire or safety ratings invalid.
What will this mean for schools? Initially it will probably create some challenges. Different supply chains may need to be established. The characteristics, limitations and listings of new products will need to be learned. And code changes will need to be incorporated.
Determining the appropriate product for a particular school will depend on several factors:
Fire rating - Not all fire-rated glass has been tested to the same standards. Verify the fire rating required for an opening and make sure the glass specified meets those requirements without special qualifications or disclaimers. Glass in doors, sidelites and near floors is at the greatest risk for breakage and needs to be able to withstand high impact.
Impact rating - There are different levels of protection. Depending on the location of the glass, you may need greater impact resistance. Again, check the code requirements carefully.
Maintenance - If a glass product is utilized that has a surface applied film, expect greater maintenance needs. More durable products are preferable. There is frequently a difference between initial cost and long term value. Also, keep in mind whether or not a product can be stocked for quick replacements when breakage occurs.
In the long run, school design stands to benefit from the change in codes. The alternatives to wired glass bring options in fire-rated openings that were never before possible. Schools will be able to incorporate products that reduce liability and improve aesthetics. Permanent labels on the wireless fire-rated glazing options will also make for easy identification by code and fire officials.
The bottom line is that schools and athletic facilities will be safer places because of the new rules for fire-rated glass. Protecting the lives of children makes any such change well worth the effort.
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