Environmental Engineering Reference
In-Depth Information
7.5 VEGETATED ROOF SYSTEMS
An extensive vegetated roof cover is a veneer of vegetation that is grown on and
covers an otherwise conventional flat or pitched roof, endowing the roof ( < 30
slope) with hydrologic characteristics that more closely match surface vegetation
than the roof. The overall thickness of an extensive vegetated roof may range
from 2 to 6 in. and may contain multiple layers, including waterproofing, syn-
thetic insulation, non-soil-engineered growth media, fabrics, and other synthetic
components. Vegetated roof covers can be optimized to achieve water quantity
and water quality benefits. Through the appropriate selection of materials, even
thin vegetated covers can provide significant rainfall retention and detention func-
tions. This system is built in a single-medium design, a dual-media design, or a
dual-media design with a synthetic layer.
This technology has been used successfully in Europe, especially Germany,
since the 1970s [19] and has become the standard method of reducing the vol-
ume of runoff generated in urban areas. Most cities in Germany have enacted
ordinances that require that any new or reconstructed building include a vege-
tated roof system to reduce the runoff to the city sewer system, many of which
are combined. Those cities that were effectively destroyed and rebuilt following
World War II, such as Stuttgart, have almost every rooftop covered with vegeta-
tion (Figure 7-20). Other countries have utilized this system on major commercial
buildings, such as the Schiphol International Airport in Amsterdam (Figure 7-21).
Figure 7-20 Center City, Stuttgart, Germany. Vegetated rooftops are required.
Search WWH ::




Custom Search