Extensive green roofs add a minimum saturated weight of two to seven pounds per square foot (48 to 170 kilograms per square meter).
EXTENSIVE GREEN ROOFS PROFESSIONAL
The black arts are performed by professional roofing contractors and involve all of the non-living components, the most important of which is the roof structure. Considerable effort and thought has been put into the engineering and architectural considerations for green roofs, but many of the issues in functional design are inherently horticultural in nature.Īlthough green roofing has been described as a combination of “black” and “green” arts, issues within the two arts often overlap. In the engineered ecosystem of a green roof, the drainage layer, growing medium, roof pitch, and plants interact to affect a green roof’s ability to mitigate stormwater.
These interactions mimic the functioning of natural ecosystems for instance, in a natural system, soil structure and type, slope angle, plant composition, and climate all influence the pattern of water movement. Each interacts with the other layers and components to influence the performance of the roof.
EXTENSIVE GREEN ROOFS SERIES
For instance, in the Central City District of Portland, Oregon, extensive green roof managers are expected to follow an irrigation regime that could only support summer-dormant native bulbs and hardy succulents through the dry summers.Ī green roof is constructed in a series of layers: the waterproofing membrane, drainage layer, planting medium, and plants. In some cases, green roof management practices actually conflict with the goal of the green roof. Green roof plants are expected to serve multiple functions while growing in a thin aggregate planting medium, yet our understanding of these complex and dynamic ecosystems remains limited. Extensive green roofs are harsh environments, often subjected to prolonged periods of drought, high temperatures, and intense wind these conditions are of particular concern here in the West. Structural constraints limit soil types, which, in turn, influence plant selection. However, researchers, horticulturalists, and commercial developers are increasingly creating extensive green roofs that meet specific ecological goals, such as stormwater management, reduction of the urban heat-island effect, enhanced air filtration, and habitat creation.Ĭreating an extensive green roof that provides ecological services is not easy. Such roofs have been shown to provide both aesthetic improvements (beauty and useable space) and economic benefits (reduced energy use and extended roof life). This article is based upon the results of Erin’s project, which was presented at the Seventh Annual Greening Rooftops for Sustainable Communities, held in Atlanta, Georgia in June 2009.Īn extensive green roof is a contained ecosystem with a soil depth of less than six inches (15.25 centimeters) the shallow depth results in a lighter-weight roof than a traditional intensive roof garden, thus reducing the cost of the building’s engineered structure. Photographs by Erin SchrollĮrin Schroll, a student at Oregon State University (OSU), undertook a study of extensive green roofs to determine aspects of their design, plant selection, installation, and maintenance that would enhance the goal of stormwater management in the Pacific Northwest. lanatum), and Roemer’s fescue ( Festuca idahoensis var. Cape Blanco stonecrop ( Sedum spathulifolium ‘Cape Blanco’), common woolly sunflower ( Eriophyllum lanatum var.
0 kommentar(er)
