A green roof, or rooftop garden, is a vegetative layer grown on a rooftop, planted over a waterproofing membrane.
GREEN ROOF TYPES
The number of green roof layers varies among the various green roof types, but green roofs traditionally include:
insulation, a waterproof membrane, a drainage layer such as gravel or clay, a mat to prevent erosion, soil and the plants covering the entire roof deck surface.
For successful establishment and long lasting vegetation it is crucial to consider among others, the local conditions, as the vegetation layer can be modified according to them.
Additional considerations also include:
wind exposure, air pollution, variation of temperature as well as local light and moisture conditions.