Other options are substrate based systems that are plug planted to the client s requirement or seeded for natural colonisation.
Simple intensive green roof.
Intensive systems allow the designer to create a park like setting so they are the best option for roof gardens that will be occupied.
Extensive systems are for roof areas that are out of reach and not used for other purposes.
8 to 20 per square foot.
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.
A typical growing medium depth for a semi intensive green roof is 6 to 12 inches.
You may find that they are referred to as roof gardens.
The simple intensive green roof.
Is less accessible intended for aesthetic purposes sill allows choice of vegetation requires less maintenance less structural demands is more economical compared to an intensive green roof.
To start with take a look at the most simple family of green roofs.
Intensive green roofs require the deepest soil and have the greatest impact on the structural design but they also accommodate all types of plantings including large shrubs and trees.
They require a layer of growing medium soil to support this much thicker vegetation layer.
There are three basic types of green roof system.
Besides the visual impact of an extensive green roof they also provide a natural habitat for birds and insects.
This system is able to retain more stormwater than an extensive system and provides the potential to host a richer ecology.
These are covered with low growing plants such as evergreen sedums.
1 intensive green roof if you want your roof to function as a garden and have large plants and even water features then the intensive green roof is for you.
These areas need appropriate vegetation that will make them low maintenance and self sustaining.
With this type of roof planting mediums are much deeper which can be between seven and 24 inches and can consist of lawn shrubs trees and perennials for example.
The basic anatomy of a green roof consists of vegetation growing medium filter membrane drainage layer waterproof root repellant layer roofing membrane support for plantings above thermal insulation vapor control layer and structural roof support.
Semi intensive green roof a semi intensive green roof system is characterized by small herbaceous plants ground covers grasses and small shrubs requiring moderate maintenance and occasional irrigation.
15 to 50 per square foot.
From a distance an extensive sedum roof can be mistaken for a grass field.