A green roof system is installed above a buildings waterproofing. It includes a root barrier, a drainage layer, a filter fabric, a lightweight engineered growing medium, and plants. Irrigation systems are optional but often helpful. Modern green roof technology developed in Germany in the 1960s.

Green roofs come in a variety of systems such as modular trays or loose laid/built-up layers. Green roofs vary in soil depth, weight, and plant palettes. They can be combined with other roof installations such as pathways, decking, solar panels, planters and more. Some green roofs are accessible to tenants and some are not. Green roofs are either “extensive” or “intensive”. Extensive green roofs are lightweight systems of 4” soil depth or less that usually are planted with sedum, a low growing, drought tolerant plant genus. Intensive green roofs are 6” of soil and can go as deep as 2’ or more, depending on the design  and the structural capacity of the building. These green roofs can support a diverse array of plants, shrubs, and trees. They weigh more and usually require greater maintenance.