Revised AISI Prescriptive Method Approved as American National Standard

The revised AISI Standard for Cold-Formed Steel Framing—Prescriptive Method for One and Two Family Dwellings has just been approved as an American National Standard by the American National Standards Institute (ANSI). In response to the need for increased performance by building materials in hostile weather conditions, AISI's revised Prescriptive Method has increased the wind load requirement for residential framing up to 150 mph. This change has made steel more competitive in high-wind regions such as south Florida and the U.S. Gulf Coast.

When the AISI Standard for Cold-Formed Steel Framing—Prescriptive Method for One and Two Family Dwellings was first developed, it was decided to limit the provisions to 130 mph exposure C wind. This excluded use of the Prescriptive Method from portions of south Florida and the Gulf Coast region, and was a judgment call based on perceived market needs. It was not felt that there would be a high demand for prescriptive provisions in higher-challenge areas. Since that decision, an International Code Council (ICC) Committee on Hurricane Resistant Construction was formed and work began on a Standard for Residential Construction in High Wind Regions. This committee desired that prescriptive provisions be established for areas up to 150 mph exposure C wind. A portion of the coastal region affected by Hurricanes Katrina and Rita is classified as 140 or 150 mph exposure C wind, as is a portion of south Florida.

With funding support from the Steel Framing Alliance and the supervision of Jay Larson, AISI director of Construction Standards Development, a project was initiated in February 2006 with the National Association of Home Builders (NAHB) Research Center to perform the necessary analysis and develop the substantiation for changes, which were then balloted through the AISI Committee on Framing Standards. A public review of the final document was accomplished in accordance with ANSI procedures and the revised Prescriptive Method was approved as an American National Standard on September 8, 2006. The standard will now be more useful in the regions affected by Hurricanes Katrina and Rita. It will be published on September 27, 2007 and available for purchase at the Steel Framing Alliance online store at www.steelframing.org.

Through the efforts of Robert Wills, AISI director of Construction Codes and Standards, it is also expected that the standard will be adopted by reference in the new ICC Standard for Residential Construction in High Wind Regions, which should provide a means for its adoption in south Florida and the Gulf Coast region. For more information please contact Jay Larson.

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