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UL 1256

Fire Test of Roof Deck Constructions

UL 1256

1 Scope

1.1 These requirements cover fire test methods to evaluate the performance of metallic and nonmetallic roof deck constructions subjected to internal (under deck) fire exposures for the purpose of determining the contribution of the roof covering material, insulation, and other components of the roofing system to the spread of fire within a building. As the extent of flame propagation, thermal degradation, and combustive damage are determined after roof deck constructions are exposed to controlled fire conditions, these requirements are not intended for use in describing or defining the fire hazard or risk of fire under actual fire conditions.

1.2 These requirements do not include tests to evaluate other potential hazards to roof deck constructions, such as structural integrity under fire exposure or wind uplift.

1.3 Two fire test methods are described in Parts i and ii of this Standard. One of these test methods shall be selected based on assessment of fire test experience, as outlined in 1.4, 1.5 and 1.6.

1.4 Part i describes the large scale fire test method used to evaluate roof deck constructions which by experience in actual installations were known to have contributed extensively to underdeck fire spread or, conversely, were regarded as being eligible for classification from this standpoint.

1.5 Part ii describes the small scale fire test method whereby the Steiner fire test chamber is used to evaluate roof deck constructions for resistance to underdeck fire spread. The conditions of acceptance under this test method were established by analysis of correlative data developed on a specific construction which exhibited adequate performance in the large scale fire test method described in Part i. This construction consisted of a steel roof deck, without vapor retarder or adhesives, insulated with one inch thick plain vegetable fiberboard roof insulation mechanically attached and covered with a three ply bitumen built-up roof covering with gravel surface.

1.6 For roof deck constructions dissimilar to any constructions previously evaluated under Part i, the large scale fire test method is to be conducted.