A green roof is a low-maintenance vegetated roof system that reduces stormwater runoff by absorbing and retaining the water in the soil medium for plant growth. As a result, much less water runs off the roof, as compared to conventional rooftops. They are easy to incorporate into new construction, and can be used on many existing buildings as well. Green roofs are constructed on top of existing roofs and include four basic components: a waterproofing layer, a drainage layer, a growing medium, and vegetation.These low-growing plants work well as they don’t need supplemental watering after establishment, except in extreme conditions, and they usually only require weeding once or twice a year. In addition to reducing the amount of roof runoff, the plants filter pollutants and carbon dioxide from the air and rain water. 

Another added benefit of green roofs include reduced heating and cooling needs and associated costs. Green roofs are likely to last much longer-up to twice as long-than conventional roofs, since the roofing material itself is shielded from ultraviolet light and thermal stress. Bonus: green roofs can reduce noise pollution and also serve as living habitats for birds and other wildlife!