Volume 42, Issue 10 - October 2007
Guide to Glass
Fanning the Flames
New Fire-Rated Products Offer
Versatility and Respond to Code Changes
by Charles Cumpston
The flames of change continue to swirl around fire-rated glass. Suppliers continue to broaden their product lines with products that offer architects and designers more alternatives than ever before.
“There is an increased demand for new and replacement glazing in lieu of traditional wired glass,” says William O’Keeffe, president and chief executive officer of SAFTI First Fire Rated Glazing Solutions in San Francisco. He points out that a number of new products with various capabilities have been introduced by suppliers. “Clear, non-wired alternatives have emerged such as laminated and filmed ceramics,” he says.
Jeff Razwick, director of business development for Technical Glass Products in Kirkland, Wash., says that fire-rated glazing products are now being asked to “multi-task.” “They not only block flames and smoke, but also, when needed, protect people and sensitive equipment from radiant heat, are impact-resistant, enhance security, offer bullet resistance, meet energy codes, resist hurricanes and support aesthetic design goals,” hesays. “The key to fulfilling these tasks is more sophisticated product make-ups,” Says Razwick
Scott Foote, a consultant with AGC InterEdge Technologies LLC in Sausalito, Calif., agrees that architects worldwide are utilizing larger expanses of glass in building design for a variety of reasons. “It naturally follows that if they can use larger panels of fire-rated glass when required they will move in that direction,” he says.
He adds that the number of architects utilizing new glass options is growing.
“We are seeing an adoption of new glazing technology by the architectural community in an effort to employ more light in building design. This glazing can be used in much larger panel sizes utilizing frames with limited sight line profiles. Furthermore, architects are even gravitating to butt-glazed systems. We call this kind of glazing ‘transparent walls’ because it tests to wall standards (ASTM E-119, NFPA 251),” Foote says.
Razwick agrees that architects like to utilize fire-rated glazing that doesn’t limit their design freedom. “Fire-rated glass and framing systems used to look institutional and bulky. Today’s materials allow for large, clear and wireless expanses of glazing with slender, modern-looking framing. Transparency is so critical in many designs, even when a fire rating is required, fire-rated glass can be part of the overall building design,” he says.
Razwick also makes the point that as property costs in many areas continue to increase, developers are frequently reducing the distance between adjacent buildings in order to maximize revenue space. “This can increase the need for fire protective materials on the exterior of the buildings,” he says. “At the same time, occupants are more comfortable when natural daylighting is available. These needs can be met by the new, high-performance fire-rated glazing systems, including curtainwall systems, storefronts and other exterior windows and doors.”
Safety and cost control also are drivers for market developments, adds O’Keeffe.
In the Know
“Fire-protective products block smoke and flame and their applications are limited to 20-45-minute durations for use in doors, sidelites, transoms and borrowed lites that do not exceed 25 percent of the total wall area,” he says.
“Fire-resistive products block smoke, flame and radiant heat and are used in 60- to 120- minute applications, door and walls, where the radiant heat transmitted to the non-fire side is limited to a rise of only 250 degrees Fahrenheit above ambient, even when the other side reaches temperatures more than 1,800 degrees,” he says. “Therefore, fire-resistive products have no size limitations and, when installed with an equally rated framing system, can be used floor-to-ceiling, wall-to-wall.”
Today’s sophisticated fire-rated products have evolved due to demands by changes in fire codes, and from requests from the architectural community, according to Razwick.
“Total reliance on sprinklers for fire protection in commercial construction is wishful thinking,” he says. “While sprinklers are an important part of fire protection, they can and do fail to control a fire for many reasons–low water pressure, broken or defective sprinkler heads, debris in the pipes, painted-over sprinkler heads, etc. National Fire Protection Association (NFPA) data shows that sprinklers failed to operate in 16 percent of fires. We’re not saying ‘don’t use sprinklers,’ because they can and do save lives, but a better solution is to use a balanced approach of active and passive systems together to assure property and life safety. Fire-rated glazing materials provide passive protection whether or not sprinkler systems are present or activate.”
Razwick agrees that areas such as stairwells and exit corridors must protect occupants from heat and flames, keep a fire from spreading and allow safe evacuation for occupants. “Since fire-rated glass can serve both purposes, and others, architects and designers are likely to use it in more areas of the building,” he says.
O’Keeffe also notes that the issue of radiant heat has come to the forefront of many in the architectural community of late. “Radiant heat is now being recognized with growing concern by the building community,” says O’Keeffe. “These invisible and intense electromagnetic waves travel with little or no resistance to air and can cause combustible objects on the non-fire side to ignite, or worse, diminish the chances of safely exiting an occupied space. Limiting temperature rise is already a requirement for 60-minute fire-resistive assemblies.”
All of these industry executives offer two pieces of advice: take advantage of the information available on the Internet, particularly on the manufacturers’ websites to learn about the different types of fire-rated glazing products available, and consider the fire-rated glass supplier a partner in the design effort. New knowledge is always available and they can help steer architects and designers through the fire-rated glazing information maze.
The Last Word
Architects should be aware that if the appropriate fire-rated glass isn’t used, sprinklers can cause the glass to fall out of the frame. Non-fire-rated glass that is heated by a fire and sprayed with water experiences thermal shock and shatters. Special deluge sprinkler systems may be able to overcome this problem, but only if water from the sprinklers is able to bathe the glass completely and evenly before it overheats. That’s a challenging task knowing that drapes, blinds or shutters are frequently used to cover glass.”—Jeff Razwick, director of business development for Technical Glass Products in Kirkland, Wash.
“More building code officials are examining the purpose of the hose stream test for 45-minute glazing in non-structural applications such as windows and sidelites. They are realizing that the hose stream is inconsistent with providing any safety improvements, which most other nations realized many years ago by eliminating its use in any fire test. The [General Services Administration] is one of the leading proponents of such approval practices, and most recently, cities and counties such Los Angeles, San Francisco and Honolulu are approving the use of CPSC Category II, radiant heat-reducing, clear-tempered products that cost less than ceramics in 45-minute applications.”—William O’Keeffe, president and chief executive officer of SAFTI First Fire Rated Glazing Solutions in San Francisco
Down to the Wire
Traditional wired glass (non-safety) is now required to meet Consumer Product Safety Council (CPSC) impact-safety requirements like any other glazing in a hazardous location (e.g. doors and sidelites). This, however, does not constitute a ban on wired glass. There are safety-rated wired glass products rated to CPSC Category II (the highest federal impact-safety standard).