As we enter the 2003 hurricane season, we face unpredictability from both the elements and other unknown threats that place added emphasis on the impact- and blast-resistance of a structure’s window and glazing system.
In August 1992, Hurricane Andrew swept through southern Florida. In its wake, 41 people were dead; 200,000 more were homeless; and approximately $15.5 billion in property damage was reported. For the building industry, the catastrophe signaled a new era in coastal construction that resulted in, among other things, impact standards for window and glazing systems.
Prior to Andrew, shutters covering single-paned windows were the extent of hurricane protection along most of the East Coast. The insurance industry, hard hit by billions in claims, became the catalyst for initiatives to “hurricane-harden” structures along the coastline. The image of a wooden 2x4 fully impaled through the heart of a palm tree by Andrew’s force served as a visual testament to the need for impact-resistant windows.
In 1994, Florida’s Dade and Broward counties adopted the first set of standards for windborne debris, and others soon followed. The standards require that all windows and shutters in newly constructed or renovated residential and commercial property must pass specific testing requirements. Only products that pass these impact tests would be certified for use.
Windows and shutters used in buildings three stories and less must undergo the large missile test, which involves shooting an eight-foot-long 2x4 weighing approximately nine pounds toward a shutter or window at 34 miles per hour. The small missile test, which simulates windborne roofing gravel used on many roofs, shoots two-gram steel balls at 80 feet per second. This test is for systems used above 30 feet, where smaller debris tends to cause the most damage. The third test – cyclic pressure – is designed to assimilate inward and outward pressures normally encountered during a hurricane.
An added twist to the certification process is that every glazing system used in a building must be hit, cycled, and certified in order to meet code. A smaller product than the one certified can be used without undergoing its own certification, but a larger product will not be considered certified.
Today, these windborne debris standards are part of the International Building Code (IBC) for coastal construction. Individual states, from Texas and Florida up to New England, have the right to determine how deep into the state the code needs to be implemented.
For buildings professionals, the standards do put a heavier burden on budgets and schedules. Some tips for smooth implementation include the following:
Brett R. Randall is vice president of Cranberry Township, PA-based TRACO (www.traco.com), a leading manufacturer of Custom Designed Heavy Commercial and Architectural Grade windows, doors, curtainwall, storefronts, entrances, and Impact and Blast products.
Know what the local windborne codes require. Some may differ from those recommended in the IBC.
Investigate window manufacturers to ensure their certifications are current for each window system that will be used.
If certification is needed, test in multiple arrangements and use the largest possible window configuration to avoid having to certify smaller components.
Build certification time into the construction schedule for window and glazing systems that aren’t off-the-shelf products.