Vegetated roof system designed to retain, slow, cool, and cleanse rainwater runoff on the top of buildings. Green roofs are generally planted with drought tolerant vegetation. The soil and vegetation evaporate and transpire precipitation to the atmosphere.

Applicability

Green roofs are appropriate for new and retrofit buildings at many scales from small garages to large warehouses and residential complexes. The load bearing capacity of the roof may dictate the type of green roof used.

Benefits

• Significantly reduces runoff volumes and rates (50 - 90% reduction in annual runoff) as well as thermal loading of runoff.
• Extend the life of roofs two to three times (20 years or more) by protecting the roofing system from inclement weather and solar radiation.
• Can help meet detention requirements.
• Reduces the urban heat island effect.
• Can reduce heating and cooling energy requirements.
• Creates opportunities for outdoor space as roof top gardens.
• Creates habitat and preserves biodiversity in an otherwise sterile urban landscape.

Watch a virtual tour of the ASLA Green Roof.

More about the ASLA Green Roof.