Green Roof
A roof planted with a full or partial covering of vegetation. Typically, a waterproof membrane is used to prevent water seepage. Green roofs have several purposes: to provide a space for growing of fruits and vegetables; to add aesthetic value to a small, cramped or otherwise inorganic space; to reduce heating and cooling burdens; and to filter pollutants from stormwater. Modern green roofs were first developed in Germany in the 1960s. Today they are used in much of Europe and the United States.
Green roofs may require additional structural support in order to offset excessive weight. While a green roof may cost $8 per square foot or more, users often recoup some of the outlay with lowered heating and cooling costs – vegetation is a good insulator. Traditional built-up roofs start at about $1.25 per square foot.
Sources:
-- “Green Roof,” Wikipedia Web site. http://en.wikipedia.org/wiki/Green_roof
-- “Heat Island Effect: Green Roofs,” EPA Web site. Accessed Sept. 5, 2007. http://www.epa.gov/hiri/strategies/greenroofs.html
