The International Code Council (ICC) recently approved a comprehensive set of building code changes based on recommendations from the Commerce Department’s National Institute of Standards and Technology (NIST) findings from a three-year investigation of the collapses of New York City’s World Trade Center (WTC) towers on Sept. 11, 2001. The changes will be incorporated into the 2007 supplement to the ICC’s International Building Code (IBC).
The code changes address areas such as increased resistance to building collapse from fire and other incidents, use of fireproofing, performance and redundancy of fire protection systems, fuel oil storage/piping, elevators for use by first responders and evacuating occupants, the number and location of stairwells, and exit path markings.
The model code changes consistent with the NIST WTC investigation recommendations that are now required by the IBC include the following:
- an additional exit stairway for buildings more than 420 feet tall;
- a minimum of one fire service access elevator for buildings more than 120 feet tall;
- Increased bond strength for fireproofing;
- field installation and inspection requirements for fireproofing;
- increasing by one hour the fire-resistance rating of structural components and assemblies in buildings 420 feet and taller;
- explicit adoption of the "structural frame" approach to fire resistance ratings; and
- luminous markings delineating the exit path (including vertical exit enclosures and passageways) in buildings more than 75 feet tall.
Two more model code changes will be considered for the next edition of the IBC in 2009. More information, including a web-based system for tracking progress toward implementing all of the NIST WTC recommendations, is available at https://wtc.nist.gov.