Green Roof Building Information

A planted or green roof is simply a ballasted roof system installed on a flat or low slope roof, except the ballast consists of a planting medium and plants. The two basic types of roof are extensive (requiring limited maintenance or access) and intensive (requiring significant maintenance and access).

Overall, the benefits of a planted roof include increasing insulation value, reducing stormwater runoff, improving water quality, reducing urban heat island effect, conserving energy, reducing sound reflection, creating wildlife habitat, and improving the aesthetics of the typical roof. An often overlooked benefit–and one with significant asset management impact–is the prolonged life of the roof membrane. Because a planted roof protects the membrane from the sun’s ultraviolet radiation, extreme temperature swings, and harmful pollution, the roofing membrane can last 50 to 100 years. GSA's oldest planted roof was installed in 1975.