Roofs for Healthy Cities
2005 North American Green Roofs of Excellence Award
Type III - 5.00 inches
This green roof landscape occupies the thirty-foot-wide fourteenth floor terrace surrounding the penthouse office space, currently the Heinz 57 Corporate headquarters. Formerly a Gimbels department store, the fourteen-story steel-frame structure in the heart of Pittsburgh’s densely populated business district, the building is considered an historic landmark and a visual anchor for the district. In 1998, the architectural firm of Burt Hill Kosar & Rittlemann Associates (now Burt Hill) was retained to develop a renovation plan for the aging structure, vacant since 1984. The project was part of city-wide effort to restore the urban core of Pittsburgh.
The design included the addition of a fifty-foot-diameter octagonal atrium in the middle of the structure spanning the fourteenth floor to the seventh floor. Enticed by the resulting light on the one-acre interior floor plate, the Heinz Company made the decision to locate their North American operations headquarters in the top seven floors of the building.
The architects retained Roofmeadow to design a green roof on the terrace surrounding the executive offices, as a compliment to the atrium. The green roof provides views of a rooftop meadow from the executive offices. The integrated decks and paved patio areas can be used for out-door meetings and informal gatherings, allowing employees to experience a landscape beyond the glass-curtain walls. The ground cover provides an acoustical damper in the brick and glass-enclosed terraces.
Roofmeadow elected to use a two-layer Type III assembly, with three inches of growth media over two inches of drainage media, engineered to enhance the drought-resistance of the un-irrigated green roof ecosystem. The Burt Hill landscape department designed the undulating rhythm of the planting. Roofscapes selected the appropriate plant varieties to achieve variation in height, texture, color and bloom time. In the early spring plants like Phlox, Festuca, and Allium scoenoprasum are present. In the summer Tradescantia, Chrysanthemum and Anthemis steal the show. The penthouse building and the high parapet walls, combine to create changeable micro-climatic conditions. A wide range of plants, able to tolerate the variable roof top environment were specified. The diverse plant palette includes 31 xeric species, comprised of a variety of herbs, grasses, perennials and Sedums (including 6 North American natives). The plants were established from plugs and seeds and protected from wind scour during establishment by a photo-degradable ‘wind blanket.’
Paved patios, constructed to encourage the free flow of water between the paved and vegetated areas, are integrated with high-density recycled plastic lumber roof decks allowing the building inhabitants to easily occupy the space. The green roof helps to make the amenity spaces desirable by dramatically lowering the summertime temperatures on the terrace.
Based on European experience with similar systems, the green roof is expected to double or triple the life of the underlying waterproofing. The thriving project is visible from most of the major downtown office towers. It demonstrates how green roofs can reduce the heat island effect and improve the habitability of urban office spaces.
12,000 square feet