The City Hall greenroof, is located at the Atlanta City Hall building on the fifth floor adjacent to the City’s cafeteria. The project is 3,000 square feet with approximately 2,000 square feet of vegetated area and 1,000 square feet of pavers. The space once functioned as patio, and thus the design sustained the patio area for staff use. Additionally, the greenroof is accessible to all that visit the building. It is visible by surrounding buildings that are above the fifth floor of City Hall.
The plants are predominantly sedums with some perennials, cacti, and herbs. The landscape plan called for over 2,800 plants from 31 species. The soil varies in depth from 3 to 10 inches, and 70 cubic yards of soil was installed on the roof. Structurally the building was designed to hold approximately 560,000 pounds, or 186 pound per square foot. With the construction of the greenroof, 175,000 pounds (58 pounds per square foot) was added to the structure.
The greenroof was designed with no supplemental irrigation system. In the design, a one-inch PVC line was installed along the perimeter of the greenroof as well as from each drainage box to drainage box. The one-inch conduit is available for monitoring equipment or supplemental irrigation if needed.
The greenroof was officially completed on December 18, 2003. The Mayor and City Council informally opened the greenroof to City employees just days after it was completed. The greenroof at City Hall has been featured in recent media as a component to green building strategies. In April the Mayor officially dedicateed the greenroof as a feature of Atlanta City Hall, Georgia, USA.