Today’s fire rated doors frequently incorporate glazing to enable vision and transparency that maximize natural or shared lighting as well provide additional security to areas that would be otherwise closed-off. Having large vision panels in fire doors provide important safety functions as well. During a fire, first responders are able to see inside the room and visually assess the situation, enabling them to be more effective.
However, the glazing used in fire rated doors typically have additional fire and safety requirements, which can be confusing. Over the years, the International Code Committee (ICC) has endeavored to clear up this confusion by adding specific provisions in the building code.
For well over 100 years, traditional wired glass was the only fire rated glass product available, and was widely used in fire doors in schools, hospitals and commercial construction in general. It was mistakenly perceived as “safety glazing” because the embedded wires gave the illusion of increased strength and impact resistance, when in fact, the opposite is true. Wire actually weakens the glass, making it half as strong as ordinary window glass. It breaks easily on human impact, exposing razor sharp wires that can trap a victim’s limb in the opening and increase the severity of the injury.
In 1997, the Consumer Product Safety Commission (CSPSC) enacted a federal safety glazing standard (16 CFR 1201) to protect people from injury due to accidental impact with glazing. The building codes apply the CPSC standard to require that glazing used in hazardous locations, such as doors and sidelites, must meet minimum Category I and II impact standards, depending on the size of the glazing panel. Smaller glazing panels in sizes up to 1,296 square inches must meet the Category I impact test of 150 ft. lbs. Larger glazing panels must meet the higher Category II standard impact test of 400 ft. lbs. of impact resistance.
At the time that the new CPSC requirements were enacted, traditional wired glass was granted a temporary exemption from meeting the CPSC standard, which meant that it only had to meet the lesser ANSI Z97.1 standard, which provided a lower 100 ft. lbs. impact test. However, independent testing performed on traditional wired glass demonstrated that it fails with as little as 50 ft. lbs., a force easily created by a five-year-old pushing on the glass.
This all changed in the 2003 IBC, when traditional wired glass lost its exemption from meeting safety glazing standards when used in educational and athletic facilities. In the 2004 IBC Supplement and the 2006 IBC, traditional wired glass is no longer exempt when used in any hazardous location for all new construction and in all types of occupancies. Replacement glazing must also meet the minimum CPSC Category I and II requirements. Furthermore, all glazing used in gymnasiums or athletic facilities must meet the more stringent Category II requirement when used in any area subject to human impact load, regardless of size.