A 2006 study by the university of michigan comparing costs of conventional and green roofs showed that on average installing a green roof costs about 22 00 sq.
Extensive green roof v intensive green roof.
There are two ways of planting a roof.
Intensive includes a thick layer of soil that can support large vegetation such as small trees.
It also allows for a formal garden to be installed with paths grass lawn and flowers or pot plants.
Almost always used for new construction intensive green roofs can be anything from a public garden to an entire park as is the case with the world s largest green roof millennium park in chicago which is 24 5 acres of landscaping on top of two subterranean parking garages.
The plants that are mostly used on extensively planted roofs include grasses mosses herbs and.
These systems range in thickness from 2 6 94 and weigh approximately 15 30lbs per sq ft.
The green roof as a habitat.
8 to 20 per square foot.
Extensive green roof systems extensive systems are simpler and lighter weight than intensive systems.
An extensive green roof is characterized by a thinner layer of soil and smaller plants.
Due to their light weight and low profile they require less structural support and can be used on roofs with a slope of 30 b0 and higher.
Typically these roofs will have more soil and some small shrubs as well as the low growing wildflowers and sedums found on an extensive roof.
The distinction is based on the kind of plant involved.
Planted roofs create living space for animal species.
A semi intensive green roof can give rise to a richer ecology with more diverse plant and animal species.