As seen in Life Safety Digest, April 2009
Glazing for Life Safety in Educational Facilities
By Jeff Razwick
The U.S. Fire Administration reports that while fire deaths are rare in primary and secondary schools, the injury rate is approximately 50 percent higher than the average for all non-residential structures (22.0 injuries per 1,000 fires in schools versus 14.4 for other buildings)1. Incendiary or suspicious fires predominate, accounting for 37 percent of all school structure fires – and 52 percent of fires in middle and high schools.
At the college level, the National Fire Protection Association (NFPA) reports that dormitory fires increased 3 percent from 1980 to 2005, despite a 52 percent decrease in structure fires of all types during the same period2. Cooking equipment is the leading cause of such fires, responsible for 72 percent of incidents in 2002 – 2005.
Educational facilities present several potential challenges for addressing life safety: frequent false alarms, older buildings without adequate sprinkler protection, and large numbers of people needing evacuation.
Effective building compartmentation plays a key role in protecting students and staff from fire. In refurbishment of older buildings, as well as new construction, awareness of the role of fire-rated glass and frames, as well as the proper applications for various types of glazing, is an important part of overall building compartmentation.
Code Issues
A key code issue related to fire-rated glazing is local jurisdictions’ ongoing adoption of the 2006 International Building Code (IBC), which eliminates the use of traditional polished wired glass in hazardous locations. Wired glass had been a staple of fire protection in schools for decades due to its affordability and ready availability.
While such glass is effective at blocking the spread of flames and smoke, it is relatively low strength and therefore susceptible to breakage in the course of everyday use – such as is common in busy school hallways and classrooms where students may bump into it. Because of the potential for injury from broken wired-glass, the IBC now prohibits it in typical ‘safety glazing’ areas such as doors, sidelites, windows near the floor, and other areas at risk for impact. Fire-rated glass in these applications must now meet impact safety ratings of the Consumer Product Safety Commission’s (CPSC) Safety Standard for Architectural Glazing Materials.
Prior to the 2006 code change, the 2003 IBC restricted wired glass in hazardous locations in schools, athletic facilities and daycares. Now the code extends the restriction to hazardous locations in all building types.
Because wired glass is still prevalent in schools, inspection and maintenance programs should seek to identify and replace such glass used in hazardous locations with impact-resistant fire-rated glazing as soon as practical, or when required by code during building upgrades.
Fire-Rated Glazing Options
In recent years, manufacturers have introduced a wide range of fire-rated glazing products. These advanced materials can meet nearly any design or performance requirement – from aesthetic appeal to impact safety resistance to boosting building security and energy efficiency. New classes of materials, and more sophisticated product make-ups, expand the range of alternatives.
Two notable fire-rated glazing classes are ceramic glass and transparent wall panels.
Ceramic glass
With the look of ordinary window glass, transparent ceramic sheets are becoming the standard for many fire-rated glazing applications historically served by wired glass. Depending on the product, and product make-ups, ceramic glass offers fire ratings up to three hours in doors (90 minutes in other applications), high impact safety ratings, sound reduction, and other performance benefits. The material can be beveled, etched or sandblasted without affecting the fire rating. An example product in this category is the FireLite family of materials.
Lamination and surface-applied fire-rated films enable ceramic glass to meet the highest standard of impact safety for glass – CPSC Category II, Safety Standard for Architectural Glazing Materials. Such glazing is able to safely withstand an impact similar to that of a fast moving, full-grown adult.
Ceramic glass can also be incorporated into insulated glass units (IGUs) in conjunction with many types of tempered or float glass, including tinted, low-emissivity, and mirrored products. Such IGUs not only provide fire protection, but can also help with a building’s energy efficiency – especially important for cash-strapped schools and for meeting more stringent energy requirements in codes.
Whether included as part of an IGU or not, the specification of fire-rated glazing should also take into account the fire rating of the framing. To ensure adequate fire protection, the framing should carry a fire rating equivalent to the glazing. Manufacturers now offer a range of fire-rated frames, including narrow profile steel frames, as well as fire-rated hardwood frames.
Transparent wall panels
While fire-rated ceramic glass works well in many applications, other products should be used in instances where it is necessary to protect people and equipment from high heat. Ceramics can withstand the high temperatures of a fire without breaking, but allow radiant and conductive heat to pass through.
For exit corridors, stairwells, and rooms with heat sensitive computer equipment, transparent wall panels may be appropriate. Glazing in this category is tested to the same standards as solid walls, with fire ratings up to 2 hours. In addition to stopping flames and smoke, such glass firewalls also block heat transfer, similar to a fire-rated masonry wall.
Transparent wall panels can be installed from wall to wall and floor to ceiling, and are also available for doors. Some transparent wall panels utilize older technology with insulated glass units filled with a clear gel that turns to opaque foam during a fire. Other products use a newer technology that incorporates multiple layers of glass with intumescent interlayers. One type of product in this latter class is Pilkington Pyrostop.
Labeling and Inspections
Whichever type of fire-rated glazing is specified, it is important during inspections to ensure it has passed all testing requirements, and is listed by a trusted third-party agency such as Underwriters Laboratories (UL). Be wary of any material that does not pass all required testing, or of manufacturers who ask for specific product exemptions or approval from the local authority having jurisdiction (AHJ). Such products may be presented as a low-cost replacement for traditional wired glass. However their inability to meet standard fire testing requirements should raise a red flag.
It is also critical during inspections to ensure that the glazing meets the required fire rating, and is appropriate for the specific building location. Fire-rated glazing labels provide inspectors, at a glance, the fire-rating in minutes (from 20 minutes to three hours), the tests the material has passed, and whether it is suitable for doors, openings or walls. For more information, see “Inspecting Fire Rated Glazing: Clear-Cut Labeling System Helps Ensure Proper Usage,” Life Safety Digest, October 2008.
Jeff Razwick is the Vice President of Business Development for Technical Glass Products (TGP), a Snoqualmie, Washington-based supplier of fire-rated glass and framing systems, along with specialty architectural glass products. www.fireglass.com, 800-426-0279
Notes
1) “School Fires: Topical Fire Research Series, Volume 4 – Issue 6,” U.S. Fire Administration, National Fire Data Center, December 2004.
2) Obtained from nfpa.org February 4, 2008. Fire data for dormitories include those at schools, colleges and universities, as well as fraternity and sorority houses, monasteries, bunkhouses and similar facilities.