Before installation of the overburden, managers should schedule a flood test of the system. Water should be at least 2 inches deep at all details. If a detail fails, the installer must retest it after repairs.
Vegetative roofs offer significant benefits related to sustainability that building owners and managers seek. But to ensure system longevity, managers must specify proper materials and detailing. Otherwise, the cost to repair or replace a leaking vegetative roof system dramatically reduces these sustainability benefits.
When specifying a vegetative roofing system, managers must consider system details carefully.
Base flashing. For conventional roofs, the top edge of the base flashing must be at least 8 inches above the membrane surface. For vegetative roofs, the top edge of the flashing system should be at least 8 inches above the top of the planting system.
Penetrations. For all roof systems, managers must minimize penetrations to reduce the potential for leaks. Due to access constraints and challenges, this issue is more important in vegetative roofs.
Gravel. Managers should specify that installers use gravel at perimeters and around penetrations and details so water can flow promptly away from these areas.
Drains. Managers need to specify dual-level drains to ensure water can drain from the top surface of the overburden and the waterproofing-membrane layer.
Planters. For plants with deep root structures, such as trees and shrubs, managers should specify independent planter boxes to separate the roots from the waterproofing system.
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