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

1.2 The practice addresses the loads associated with vegetative (green) roof systems. Components that are typically encountered in vegetative (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 practice also addresses the weight of the vegetative (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 drain layer is completely filled with water. The first condition is considered the dead load of the vegetative (green) roof system. The difference in weight between the first and second conditions, approximated by the weight of transient water in the drain layer, is considered a live load.

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