The wind resistance of ballasted membrane roof systems is determined largely by the size and weight of the ballasted used. ANSI/SPRI RP-4 provides a method for the wind design of ballasted single-ply membrane roof systems and includes specific guidelines for the size and weight of aggregate used as ballast. The aggregate size classifications provided in this standard are intended for use with the guidelines provided ANSI/SPRI RP-4 in designing the wind resistance of aggregate ballasted single-ply membrane roof systems.

The aggregate size classifications provided in this classification are intended to provide a basis of compliance for contract documents’ that specify certain aggregate sizes for use on ballasted membrane systems.

1.1 This classification defines the aggregate size designations and ranges in mechanical analyses for standard sizes of aggregate used as ballast for membrane roof systems.

1.2 The text of this classification 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.

1.3 With regard to sieve sizes and the size of aggregate as determined by the use of testing sieves, the values in inch-pound units are shown for the convenience of the user; however, the standard sieve designations shown in parentheses is the standard value as stated in Specification E11.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.5 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.