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Fire Performance of an Interstitial Space Construction System (NISTIR 5560)



James R. Lawson, E Braun, Laurean A. DeLauter, G Roadarmel


An interstitial space building construction assembly, consisting of a walk-on deck suspended from above by structural steel which also supported a functional floor, reproduce a design planned for use in a new hospital complex at Elmendorf Air Force Base, Alaska. This interstitial space assembly was built in the multi-story steel test structure at the National Institute of Standards and Technology. The construction assembly was tested by the same protocol used to evaluate the Veteran's Administration interstitial space construction assembly, tested in 1984. This protocol followed the National Fire Protection Association's, NFPA 251 Fire Tests of Building Construction and Materials Standard, 1990 edition. Fire testing of the interstitial space system was carried out during the summer of 1994. This construction assembly met the requirements for a 2 hour fire endurance rating. The maximum surface temperature on the unexposed functional floor above the interstitial space reached 33 deg C (91 deg F) at the end of the two hour period. The maximum structural steel temperature inside the interstitial space was 123 deg C (253 deg F). The structural assembly was evaluated for a total of 2 hours and 30 minutes before the test was terminated.
NIST Interagency/Internal Report (NISTIR) - 5560
Report Number


interstitial spaces, structural systems, fire endurance, fire research, fire tests, floor systems


Lawson, J. , Braun, E. , DeLauter, L. and Roadarmel, G. (1995), Fire Performance of an Interstitial Space Construction System (NISTIR 5560), NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed May 24, 2024)


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Created February 1, 1995, Updated November 10, 2018