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Fire Performance of Interstitial Space Construction Systems.



James R. Lawson


Two unique walk-on deck construction systems were exposed to the standard NFPA 251 time-temperature fire exposure for periods up to two hours in order to evaluate their fire performance. A large scale steel structure was used in the test program to simulate construction systems found in the field. The structure consisted of two large functional floors separated by an interstitial space in which a walk-on deck was suspended from the top functional floor. One of the walk-on deck systems was constructed from lightweight concrete, and the second was built with poured gypsum. Critical components evaluated were the top functional floor, unprotected steel work in the interstitial space, the walk-on deck system, and protection for a heavy steel column located in the center of each test bay. Test data were compared with the fire endurance test requirements of NFPA 251. Computer predictions also were made using the FIRES-T3 model to determine its ability to accurately predict the construction system performance. The interstitial construction system achieved the design fire endurance.
NIST Interagency/Internal Report (NISTIR) -


fire endurance, fire tests, interstitial spaces, NFPA 251, steel structures, floors, lightweight concretes


Lawson, J. (1985), Fire Performance of Interstitial Space Construction Systems., NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed June 15, 2024)


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Created May 1, 1985, Updated February 19, 2017