5.1 This test method is designed to provide a basis for estimating one aspect of the fire exposure behavior of exposed insulation installed on the floor of an open attic. The test environment is intended to simulate attic floor exposure to radiant heat conditions. Radiant heat has been observed and defined in full-scale attic experiments.

1.1 This test method covers a procedure for measuring the critical radiant flux of exposed attic floor insulation subjected to a flaming ignition source in a graded radiant heat energy environment inside a test chamber. The test specimen can be any attic floor insulation. This test method is not applicable to those insulations that melt or shrink away when exposed to the radiant heat energy environment or the ignition source.

1.2 This test method measures the critical radiant flux at the farthest point to which the flame advances. It provides a means for relative classification of a fire test response standard for exposed attic floor insulation. The imposed radiant flux simulation levels of thermal radiation are likely to impinge on the surface of exposed attic insulation from roof assemblies heated by the sun and by heat or flames of an incidental fire which has the potential to involve an attic space. This test method is intended to simulate an important element of fire exposure that has the potential to develop in open attics, but is not intended for use in describing flame spread behavior of insulation installed other than on an attic floor.

1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.

1.4 This standard is used to measure and describe the response of materials, products, or assemblies to heat and flame under controlled conditions, but does not by itself incorporate all factors required for fire hazard or fire risk assessment of the material, products, or assemblies under actual fire conditions.

1.5 Warning—Fire testing is inherently hazardous. Adequate safeguards for personnel and property shall be employed in conducting these tests.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.