8 to 20 per square foot.
Intensive vs extensive green roof system.
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.
These systems are ideal for efficient stormwater.
It also allows for a formal garden to be installed with paths grass lawn and flowers or pot plants.
Extensive green roof systems extensive systems are simpler and lighter weight than intensive systems.
A semi intensive green roof can give rise to a richer ecology with more diverse plant and animal species.
Extensive green roofs.
Semi intensive roofs are generally used within highly visible area s to improve aesthetic design using small shrubs forbs and grasses.
This is most noticeable in intensive green roofs since there is a thicker and more consistent layer of soil which provides a higher insulating value.
Extensive green roof an extensive green roof system is characterized of its vegetation ranging from sedums to small grasses herbs and flowering herbaceous plants which need little maintenance and no permanent irrigation system the growing medium depth for an extensive green roof system is typically 6 inches or less.
These systems range in thickness from 2 6 94 and weigh approximately 15 30lbs per sq ft.
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.
For a conventional roof.
Mosses sedums herbs and low growing grasses are common choices for extensive roofs.
15 to 50 per square foot.
There are no specific requirements for a green roof insulation layer in a simple extensive green roof.
You want to ensure that any roofing insulation is compatible with green roofs.
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.
Intensive green roofs can support the growth of a wide range of plants including shrubs and small trees while the extensive green roofs can typically only accommodate a small selection of drought tolerant plants with shallow root systems.