Green Roofs
Green roofs are a type of protected-membrane roof system (aka Inverted Roof Membrane Assembly) where the thermal insulation or another material is located above the waterproofing membrane. 
The engineering benefit of protected-membrane roofs is that the waterproofing membrane is protected from ultraviolet rays, thermal shock, and multiple types of physical damage from the elements and also from human beings.
Green or turf roofs are made by using soil or other growth media on the protective membrane of the roof and seeding it. Maintenance is done by inspecting the roof for invasive and unwanted plants with roots that will grow and damage the membrane. The growth of media and plant life can provide an excellent thermal buffer for the building. Moreover, this buffer will also store the heat and slowly release it into the building envelop much like an adobe or cob structure – thus making it more energy-efficient.
With all plant life, there is a fire concern. Plants are not fireproof so it is important for the design of any green roof to take this into consideration. The strategic placement of fire barriers or borders is usually made up of fire-retardant materials like rock and gravel.
Green roofs are known to be a benefit to the environment. In areas of high pollution, green roofs provide clean oxygen through the carbon-oxygen cycle in plants. Besides benefiting the natural environment, green roofs are great for the work environment. The pleasing atmosphere is great for entertaining clients as well as increasing morale and production in employees.
Another added benefit that has been seen in areas with large amounts of rainfall and floods, is that the green roofs reduce flooding by absorbing (buffering) some of the rainfall. This is dependent on the type of growth media and plant selection that compliments the load integrity of the roofing structure.
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