Standard Active Last Updated: Aug 12, 2021
ASTM D7746-21

Standard Practice for Calculating the Superimposed Load on Wood-frame Floor-Ceiling Assemblies for Standard Fire-Resistance Tests

Significance and Use

4.1 Test Methods E119, E1529, and other standard fire resistance test methods specify that throughout the fire-resistance test, a constant superimposed load shall be applied to a load-bearing test specimen to simulate a maximum allowable load condition. This superimposed load shall be the maximum load allowed by design under nationally recognized structural design criteria for the tested floor configuration (that is, joist selection, spacing, and span).

4.1.1 For this practice, the nationally recognized structural design criteria to be used to determine the maximum load condition are those for the allowable stress design (ASD) method in the NDS (National Design Specification for Wood Construction).

Note 1: The NDS should be used to ensure calculation of the superimposed load is in compliance with all applicable provisions of that standard. Appendix X1 describes how to calculate the superimposed load in accordance with the NDS.

4.1.2 Alternatively, the standard fire resistance test methods shall be permitted to be conducted by applying a load less than the maximum allowable load in 4.1.1 for the tested configuration; however, these tests shall be identified in the test report as being conducted under restricted loading conditions.

4.2 This practice describes procedures for calculating the superimposed load to be applied in standard fire resistance tests of wood floor-ceiling assemblies. Practice D6513 provides a similar methodology for calculating the superimposed load on wood-frame walls.

4.3 Statements in either the fire resistance test method standard or the nationally recognized structural design standard supersede any procedures described by this practice.


1.1 This practice covers procedures for calculating the superimposed load required to be applied to load-bearing wood-frame floor-ceiling assemblies throughout standard fire-resistance tests.

1.2 These calculations determine the maximum superimposed load to be applied to the floor-ceiling assembly during the fire resistance test. The maximum superimposed load, calculated in accordance with nationally-recognized structural design criteria, shall be designed to induce the maximum allowable stress in the wood floor-ceiling fire test configuration being tested.

1.3 This practice is only applicable to those wood-frame floor-ceiling assemblies for which the nationally recognized structural design criteria are contained in the National Design Specification for Wood Construction (NDS).

1.4 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.

1.5 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.

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

1.7 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.

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Book of Standards Volume: 04.10
Developed by Subcommittee: D07.05
Pages: 5
DOI: 10.1520/D7746-21
ICS Code: 13.220.50; 79.080