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A green roof is a conventional roof covered with a layer of vegetation, also known as “living roofs”. Green roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, creating a wildlife habitat and helping to lower urban air temperatures and combat the urban heat island effect. There are two types of green roofs: intensive roofs, which are thicker and can support a wider variety of plants but heavy and require ongoing maintenance, and extensive roofs, which are covered in a light layer of vegetation and are lighter than an intensive green roof.