A green 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.
There are two types of green roofs:
Extensive green roofs have less growing medium and have a limited plant palette therefore they can be very lightweight, require less maintenance and are more economical.
Intensive green roofs have a deeper engineered growing medium and support a wider variety of plants, shrubs and trees. They are heavier, require more maintenance, and are costlier.
- Reduction in storm water runoff that affects quality of local water resources which supply drinking water, are used for swimming, and serve as fish and wildlife habitat
- Reduction in energy consumption
- Reduction in the urban heat island effect and associated cooling costs
- Creation of more natural green spaces, habitats for birds and urban biodiversity.
- Opportunities for local food production
- Doubles or triples lifespan of the roof membrane