5.1 The flexural properties evaluated by this test method are intended to provide any one or all of the following:

5.1.1 Data on the comparative effects of fire-retardant chemical formulations and environmental conditions on the flexural properties of plywood.

5.1.2 Data for use in developing modification factors for the allowable design properties of treated plywood when exposed to elevated temperatures and humidities.

5.1.3 Data comparing variables, such as other plywood species and dimensions.

5.2 Results obtained from tests conducted and analyzed in accordance with the procedures of this test method are suitable for use with other information to establish recommended roof sheathing spans for fire-retardant treated plywood.

Note 1: Temperatures lower than the test temperature specified in this test method and the cumulative effects of the elevated temperatures and humidity exposures expected to be encountered in service should be taken into account when recommended roof sheathing spans are established.

Note 2: Practice D6305 can be used to extend the laboratory strength data obtained by this test method to design value recommendations. The test data determined by this test method are used to develop adjustment factors for fire-retardant treatments to apply to untreated plywood design values. The test data are used in conjunction with climate models and other factors.

1.1 This test method is designed to determine the effect of exposure to high temperatures and humidities on the flexure properties of fire-retardant treated softwood plywood. In this test method, plywood is exposed to a temperature of 77°C (170°F).

1.2 The purpose of the test method is to compare the flexural properties of fire-retardant treated plywood relative to untreated plywood. The results of tests conducted in accordance with this test method provide a reference point for estimating strength temperature relationships. This test method is intended to provide an accelerated test at elevated temperatures and controlled humidities of plywood sheathing treated with the same chemical formulation(s) and processing conditions as plywood used commercially.

1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.

1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.