The green roof at ASLA headquarters is an excellent example of green infrastructure – a landscape that nurtures as it nourishes.  It is infrastructure in that it is literally the roof over the heads of ASLA staff. Designed by Michael Van Valkenburgh Associates, the green roof nurtures, in that it creates a tranquil setting above the city with its enveloping sweeps of groundcovers and perennials, creating a cozy nook in the sky. It nourishes in that it collects and cleanses rain water prior to releasing it into its watershed demonstrating the ecological service provided by landscape.

These sloping meadows belie the fact that the depth of soil does not exceed 18 inches due to structural limitations. Lightweight Styrofoam fill makes up the base of the pair of mounds. The effect is stunning – shaping a space, focusing views, and allowing the plantings to be seen from the street below.

An interesting facet of the design is the use of metal grating for the floor material. If you look closely, you will see that groundcovers are growing beneath this porous pavement, nourished by rain water that flows right through the deck.