A green roof / grass roof / sedum roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems.
Green roofs serve several purposes for a building, such as absorbing water providing insulation, creating a habitat for wildlife and decreasing stress of the people around the roof by providing a more aesthetically pleasing landscape. They effectively utilise the natural functions of plants to filter water and treat air in urban and suburban landscapes. There are two types of green roof: intensive roofs, which are thicker, with a minimum depth of 12.8 cm and can support a wider variety of plants but are heavier and require more maintenance, and extensive roofs, which are shallow, ranging in depth from 2 cm to 12.7 cm lighter than intensive green roofs, and require minimal maintenance.