A Project Story

The ASLA Headquarters Green Roof was initiated at a moment when I was working at Michael Van Valkenburgh Associates, shortly after the office had been shortlisted as one of three finalists for the High Line in New York City. Although the project ultimately went to James Corner Field Operations, the process sparked a deep interest, under Michael’s leadership, in how plant communities establish themselves in extreme conditions with minimal soil, shaped by light, shadow, and urban context. Soon after, we learned of the opportunity to design the green roof for the American Society of Landscape Architects headquarters in Washington, DC, which became a chance to explore many of those ideas in built form.

The premise of the project was both practical and aspirational. ASLA needed to replace its existing roof and chose to do so as a green roof that could serve as a demonstration project. At the time, green roofs were largely treated as technical systems and were often architecturally led from a creative standpoint. ASLA sought to shift that perspective by showing what landscape architects could bring to the design of these spaces, not only in terms of performance, but as fully realized and inhabitable gardens.

Working within the constraints of an existing building with no structural modifications allowed, we collaborated closely with Silman Structural Engineers to develop a system that could support varied soil depths and planting strategies while remaining within strict load limits. The design introduced a series of subtle landform “waves,” constructed from lightweight assemblies and foam, creating spatial variation across what would otherwise be a flat surface. These forms, which we referred to as waves, were in part inspired by Michael’s familiarity with Le Corbusier’s rooftop garden in Paris, translated here into a contemporary and performative green roof system. They allowed for a range of planting conditions, from shallow extensive areas to deeper, more diverse plant communities, organized as a living demonstration of green roof typologies.

One of the more experimental elements of the project was the introduction of metal grating suspended above planted areas, inspired by an observation I had while walking to work in New York City, where plant material was emerging through subway grates. Developed in collaboration with green roof specialist Ed Snodgrass, this idea pushed the boundaries of conventional green roof design and initially raised concerns about usability, particularly during events. Those concerns proved unfounded, as visitors moved comfortably across the surface, reinforcing the idea that these systems could be both performative and fully inhabitable.

Materially and conceptually, the project balanced environmental performance with human experience. It demonstrated that green roofs need not be purely technical infrastructure, but can also function as spatially rich, engaging, and usable landscapes. For me, working under Michael’s leadership, it was one of the first projects I was closely involved in from concept through realization, and it remains one of the more widely referenced green roofs of its scale.

Ultimately, the project stands as a reminder that landscape architecture can transform even highly constrained systems into meaningful places, and that it is not necessary to choose between ecological function and human use. With the right approach, both can be achieved.