A green roof, a low impact development (LID) strategy, is an alternate roof surface that is partially or completely covered with vegetation. A green roof absorbs, stores and evapo-transpires precipitation, creating a LID system that reduces runoff, thereby, reducing the amount of water that enters the sanitary sewer system. Green roofs can also be referred to as:
- vegetated rooftops
- living roofs
- eco-roofs
- Horizontal Vegetated Complex Partitions (VCP)
The vegetation on a green roof is planted in a growing medium contained by a waterproofing geomembrane such as BTL’s AquaArmor. Another example of a green roof is a rooftop pond which is used to treat greywater. AquaArmor liners works wonderfully for this application as well.
Green roofs serve multiple functions which include:
- absorption of rainwater
- insulation of the building, resulting in reduced energy use for heating and cooling
- wildlife habitat when planted with native and locally adapted plants
- creates an aesthetically pleasing landscape
- works to lower urban air temperatures, diminishing the heat island effect
Green roofs can be planted on both large and small buildings. They can be added to new buildings and retrofitted to existing buildings. Green roofs are heavier than traditional roofing systems and must be specifically engineered to support the weight of the green roof system which includes:
- the geomembrane
- growing medium
- vegetation
- root barriers
- drainage systems
- irrigation systems
The term, green roof, can also refer to a roof that utilizes some type of green technology such as photovoltaic panels or solar thermal collectors, which can also be used to harvest rainwater.
