This practice addresses performance characteristics for green roof systems with respect to the dead load and transient water live load of the entire system.

Determining these performance characteristics of green roof systems provides information to facilitate the assessment of related engineering aspects of the facility. Such aspects may include structural design requirements, mechanical engineering and thermal design requirements, and fire and life safety requirements.

Determining these performance characteristics of green roof systems provides information to facilitate assessment of the performance of one green roof system relative to another.

1.1 This practice covers a standardized procedure for predicting the system weight of a green roof system.

1.2 The procedure addresses the loads associated with green roof systems. Components that are typically encountered in green roof systems include: membranes, non-absorptive plastic sheet components, metallic layers, fabrics, geocomposite drain layers, synthetic reinforcing layers, cover/recover boards, insulation materials, growth media, granular drainage media, and plant materials.

1.3 This procedure also addresses the weight of the green roof system under two conditions: (1) weight under drained conditions after new water additions by rainfall or irrigation have ceased (this includes the weight of retained water and captured water), and (2) weight when rainfall or irrigation is actively occurring and the drainage layer is completely filled with water. The first condition is considered the dead load of the green roof system. The difference in weight between the first and second conditions, approximated by the weight of transient waterin the drainage layer, is considered a live load.

1.4 This procedure does not address point or line loads associated with architectural elements that are not essential components of a particular green roof system. These architectural elements may include pavement, walls, and masonry, and so forth.

1.5 This procedure does not address live loads associated with construction activities.

1.6 This procedure does not address live loads associated with snow or wind.

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

1.8 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 to determine the applicability of regulatory limitations prior to use.