Sourced from Building Design + Construction
Driven by Federally-mandated sustainable requirements, a 300,000 plus square-foot Vegetative Roof Assembly (VRA) was incorporated into the architectural design for the U.S. Coast Guard’s 11-level, 1.2 million square foot headquarters located in Washington D.C.
Since the U.S. Coast Guard Headquarters structure is terraced into the hillside with elevation changes of 120 feet, two levels were above-ground while the remaining nine were built into the hillside. As a result, the VRA architectural design and construction team navigated a range of unique design considerations to ultimately receive LEED Gold certification from the U.S. Green Building Council.
A cross-functional team collaborated throughout the three-phased VRA construction. Under the direction of WDG Architecture, the architect of record for the roofing, and HOK, the lead on vegetative roof components, Gordon Contracting served as the roofing contractor and Tilson Group supplied and installed the hundreds of thousands of individual vegetative roof plants.
From the outset of the project, the integrated roofing team was tasked with designing a VRA that would help decrease the building’s heating and cooling energy usage, reduce and filter storm water runoff, lower long-term maintenance and extend the life of the roof. The unique roof would also serve to integrate the 176-acre campus with the building and its 4,000 occupants.
To accomplish these objectives, the project team carefully selected performance-based product solutions that would work in conjunction to support the roof vegetation. FOAMULAR® 404 & 604 extruded polystyrene (XPS) insulations were selected for use in Protected Roof Membrane Assemblies (PRMA), where the insulation is placed directly over the membrane.