Green roof construction

Description

Green roofs are composed of several layers (waterproof membrane or existing membrane, root barrier, drainage layer, filter fabric, growing medium) that support the growth of plants and other vegetation on top of a roof.

Types

There are two main types of green roof systems: extensive and intensive.

1. Extensive green roofs have growing medium depths of 10 cm to 15 cm (0.1 m to 0.15 m), maximum structural weight loads of 250 kg/m², and vegetation is primarily limited to sedum spp or commonly known as stone crop.
2. Intensive green roofs have growing medium depths greater than 15 cm (0.15 m), no maximum structural weight load and various plant types can be incorporated including native flowers, trees and shrubs.

Within these two types of green roofs are two installation type systems:

1. Modular system: green roof component layers are fused together as a moveable modular block system that can be linked together with other green roof blocks to form the green roof. This type of system typically forms an extensive green roof type and are used where roofs are sloped and flat.
2. Layered system: all components' layers are loose laid as individual layers. This type of system can form both extensive and intensive green roofs and used typically on flat roofs.

A thin layer of vegetation and growing medium installed on top of a conventional flat or sloped roof, also referred to as living roofs or rooftop gardens.