An Innovative Green Roof
Employees of The Laclede Group, headquartered in the redeveloped General American Building in Downtown St. Louis, have a new rooftop open space to enjoy with views of Busch Stadium and the Old Courthouse thanks to an innovative green roof installed by local commercial roofing specialist Bade Roofing Company.
Located at 700 Market Street, the former General American Building (known today as 700 Market) originally opened in 1979. The six-story structure is the only St. Louis building designed by acclaimed 20th-century American architect Philip Johnson.
Bade Roofing, working with St. Louis-based general contractor Tarlton Corporation and real estate developer Koman Group, was challenged with creating a rooftop garden courtyard on the building's 5th floor and re-roofing its 6th floor. A green roof provides insulation, lowers the need for heating and cooling, and can help manage storm water. The project is currently pending LEED Certification by the U.S. Green Building Council.
Bade crews began the complex 17,800-square-foot, green roof project by first removing the existing paver ballast, two inches of EPS insulation and a 2-ply SBS modified roof system down to the structural concrete deck. A new 115-mil, fleece back loose-laid TPO roof system manufactured by Firestone Building Products, including flashing of green roof penetrations, was then installed.
Bade crews stacked three layers of loose-laid EPS insulation and a protection mat over the new TPO roof system, in preparation for a three-color concrete paver system, wood paver and pre-planted "Green Bloc" vegetation trays and leveling pedestal system.
The outdoor space incorporates raised areas filled with growth medium, various trees and shrubs planted in planter boxes, a fescue lawn area, seating areas, lighting, watering system and a gas fire pit. A 2-foot-wide buffer of landscape gravel was also installed around the roof's perimeter between the pavers and the parapet wall to aid with the courtyard's draining.
One of the biggest challenges to Bade's crew was ensuring that the green roof was completely waterproof. Any leak in the roof could potentially damage tenant spaces below.
"Getting the roof watertight as quickly as possible during each phase of installation included conducting an intensive water test, which involved flooding the roof for 24 hours to test for water tightness," said David Bade, owner of Bade Roofing Company. "Ensuring that the base roofing material was 100 percent watertight was critical on this project. Once the green roof and courtyard components are put in place, repairing a leak becomes incredibly difficult and expensive. Water tests were conducted and any weak areas in the system were quickly reinforced. After that, the roof could be flooded for an indefinite quantity of time and not be compromised.”
Re-roofing of the 17,800-square-foot, 6th floor roof started with removal and disposal of the existing gravel ballast and protection mats. The roof's 2-inch EPS insulation was removed and set aside for re-use later on the project. Bade crews then installed a 60-mil ballasted EPDM roof system by Firestone Building Products, using the saved two-inch EPS insulation, along with new protection mats and gravel ballast to complete the project.
The roof system was awarded a 20-year manufacturer's warranty with an overburden removal rider by Firestone Building Products.