There are several safe and economical alternatives to traditional wired glass for 20-45 minute vision lites
Today’s fire rated doors frequently incorporate glazing to enable vision and transparency that maximize natural or shared lighting.
Fire rated door assemblies play an important role in saving lives and minimizing property damage by providing safe egress and compartmentalizing smoke, flames and when required, dangerous radiant heat. 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. 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.
Impact Safety and Radiant Heat Considerations
Impact safety is the first consideration, and today the code states that glazing used in doors must meet CPSC Cat. I or Cat. II impact safety to protect people from injuries caused by accidental impact with the glass. It’s important to note that traditional wired glass does not meet this requirement, which means that even if traditional wired glass has a listing for use in fire doors, the code does not allow its use because it does meet CPSC safety requirements. Fortunately, there are several safe and economical alternatives to traditional wired glass for 20-45 minute vision lites that include specialty tempered, safety wired glass and 45-minute fire resistive tempered units. For 45/60/90 minute door vision lites up to 100 square inches, there is a clear specialty fire protective product that can be used. All of the products mentioned here are made in the USA and costs significantly less and performs better than filmed or laminated ceramics used in the same application.
Another important consideration is radiant heat, and there are provisions in the code to safeguard building occupants from its devastating effects. For 20 and 45 minute doors, fire protective glazing can be used up to the maximum size tested. This includes specialty tempered glass, filmed or laminated ceramics or filmed wired glass. When the door rating exceeds 45 minutes, temperature rise requirements typically apply. For 60 and 90 minute temperature rise doors, fire protective glazing is limited to 100 sq. inches. However, designers can exceed the 100 sq. inch limitation by using fire resistive glass that meets ASTM E-119 because this advanced glazing type can limit the temperature rise to 250 degrees F. Examples include fire resistive tempered units and fire resistive multilaminates. These requirements have been in effect since the 2006 and 2009 IBC, and then laid out clearly in Table 716.5 of the 2012 IBC to make it easier for architects, specifiers and code officials to enforce the provisions of the code.
Code Change Clarifies Glazing Panel Size in 60-90 Minute Exit Enclosure/Exist Passageway Doors
Before the 2012 IBC, the code had an exception that allowed fire protective glazing to exceed 100 sq. inches in door vision panels in 60-90 minute exit enclosure and passageway doors provided that the building was fully sprinklered. The ICC ad hoc committee, in recognition of the hazards of radiant heat transmission, decided to eliminate the sprinkler exception in the 2012 IBC. The presence of sprinklers in a building does not eliminate the life safety and fire spread hazard posed by the unrestricted transmission of radiant heat flux through large sizes of fire protective glazing in door vision panels in 60-90 minute doors, especially when these doors are used to protect exit enclosures and exit passageways deemed essential for life safety.
7188.8.131.52 Glazing In doors. Fire protection rated glazing in excess of 100 square inches (0.065m2) is not permitted. Fire resistance rated glazing in excess of 100 square inches (0.065m2) shall be permitted in fire door assemblies when tested as components of the door assemblies, and not as glass lights, and shall have the maximum end temperature rise of 450 degrees F (250 degrees C) in accordance with 716.5.5.
This makes it very clear that fire protective glazing cannot exceed 100 square inches, even when used in a non-temperature rise door in a fully sprinklered building. It further states that fire resistive glazing is allowed in excess of 100 square inches as long as it limits the temperature rise to 450 degrees F above ambient after 30 min. of fire exposure. Therefore, the code clarifies that fire protective glazing it is limited to 100 square inches regardless of whether the building is fully sprinklered or not.
Fire rated doors have and will continue to play an essential role in life safety and property protection. However, knowing the standards, testing and code requirements are important in order to properly specify the correct and code-approved product for the application. Designers and specifiers can always reach out to the manufacturers for expert guidance and support.
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