What makes specialty glazing special
Advances in glazing technology have allowed glass to perform important functions such as protecting against fire, hurricane, ballistics, bomb blast and more. While high-performance glazing has enabled designers to incorporate greater amounts of glass, there is no less confusion regarding its proper use. This has often led to misapplications that violate the code, resulting in additional expenses and costly construction delays. To avoid such problems, architects and glaziers should keep the following basic requirements in mind when dealing with specialty glazing:
1. Know the code. The International Building Code establishes the “minimum requirements to safeguard the public health, safety and general welfare through structural strength, means of egress facilities, stability, sanitation, adequate light and ventilation, energy conservation, and safety to life and property from fire and other hazards attributed to the built environment” (Sec. 101.3). Chapter 24: Glass and Glazing covers the general requirements for using glass in buildings and structures. If the glass is intended to perform a special function such as occupant and property protection in the event of a fire, the requirements in Chapter 7, Fire Resistance Rated Construction, shall also apply. It’s important to become familiar with local variations of model codes and the interpretations of local code officials.
2. Listing agencies all test to the same acceptance standards. Building products must be tested, labeled as approved and listed by a Nationally Recognized Testing Laboratory whose activities are governed by Occupational Safety and Health Administration. Underwriters Laboratories and Intertek/Warnock-Hersey are two of the 15 NRTLs that provide testing and listing services intended to demonstrate that a product has met the widely accepted performance standards based on the application for that jurisdiction. For end users, this means that all NRTL validations are equal since each agency has to comply with the same OSHA requirements. For manufacturers, this means that they have a choice in their testing agency. Choosing one NRTL over another has no effect on a product’s performance.
3. Testing agencies document product performance, not code compliance. Testing agencies, while claiming code compliance, do not ensure against the potential misuse of the product. With fire-rated for example, the marking does not show if the product is fire protective or fire resistant, which is important in determining code compliance. Fire-protective products, although listed for 60 to 120 minutes, are limited to 100 square inches, because they are unable to meet the temperature rise criteria that the code requires for one-hour and two-hour applications. This limitation is not indicated in the marking, and has prompted the misuse of fire-protective glazing in one-hour and two-hour walls where fire-resistive glazing should be used. The improper selection of specialty glazing based solely on an hourly rating exposes building occupants to life-threatening radiant heat and prevents them from exiting the building safely in the event of a fire. It is important to recognize that product label designations are merely an indication or confirmation of test performance. The next step is to evaluate product performance in light of code requirements.
4. Seek the manufacturer’s expertise. Whether you have questions about product performance, allowable applications or need help in understanding the code requirements, never hesitate to consult the manufacturer as a resource. They can help you understand your options and choices to ensure that the glazing product chosen is the best suited, code-compliant solution for the project.