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Post-Construction Fires Prior to September 11, 2001. Federal Building and Fire Safety Investigation of the World Trade Center Disaster (NIST NCSTAR 1-4A) ***DRAFT for Public Comments***



Erica D. Kuligowski, D D. Evans


Fires occurred in World Trade Center (WTC) I, 2, and 7 prior to September 11, 200 1. This report documents the facts of significant fires in the buildings after first occupancy as they relate to the performance of the automatic sprinkler, manual suppression, fire detection, and smoke purge systems. The ultimate goal of this review was to identify from New York City Fire Department (FDNY) records significant but not well-known fires for further study. From the information contained in FDNY fire reports and fire investigation records provided to the National Institute of Standards and Technology (NIST), 47 fires occurred in WTC 1, 2, and 7 that were of sufficient size and duration to activate multiple sprinklers or were estimated by NIST to be capable of doing so, over the time period the buildings were occupied. This total does not include the major 1975 office fire in WTC 1 or the 1993 bombing. The records indicate that in areas protected by automatic sprinklers, no fire activated more than three sprinklers. Three sprinklers would provide coverage for a floor area of approximately 675 ft2 (63 m2). This area is much smaller than the 9,000 ft2 (800 m2 damaged by the 1975 fire in an office space unprotected with automatic sprinklers. Many of the fires that occurred were recorded as suspicious or unknown in cause, occurred during off peak work hours, and involved materials such as trash or paper-based supplies. In cases where sprinklers were activated, the FDNY records indicated that the sprinklers either extinguished the fire completely or aided in controlling the spread.
National Construction Safety Team Act Reports (NIST NCSTAR) - 1-4
Report Number


World Trade Center, high rise buildings, building collapse, disasters, fire safety, fire investigations, terrorists, terrorism, construction, fire departments, codes, fire detection fire suppression, smoke purge sytems, sprinklers
Created September 1, 2005, Updated February 19, 2017