Prudential Plaza Roof Garden
Solomon Cordwell Buenz, Jones Lang LaSalle, Telos Group
Wolff Landscape Architecture, Inc. (WLA) was hired by the client to design a rooftop garden as the outdoor component of the 11th floor tenant amenity floor, which also includes indoor bar and lounge areas. The landscape architect was the design lead for the roof garden, but worked closely with Solomon Cordwell Buenz, the architect, and the structural engineers in order to respond to project goals, program requirements, and structural constraints. The new roof garden brings tenants and other users past a central lawn through rich garden areas on either a walkway with steps or a ramp that gets people above the roof’s parapet, where they enjoy unparalleled views of Millennium and Grant parks and Lake Michigan through a transparent glass perimeter safety railing.
The roof garden’s central lawn, stage, and terraced seating accommodate large gatherings as well as concerts, other special events, and informal use by small groups and individuals. Other spaces and facilities include a self-service bar with trellis (that can also be staffed by caterers), a fire pit lounge with trellis, and open terraces and smaller spaces that accommodate smaller groups and individuals.
The thin structural slab and limited load capacity were a severe constraint on the design. The allowable dead load of 30 pounds per square foot (PSF) accommodated only a 5” soil depth, with trees located near columns. In order to achieve adequate soil depth the dead load was distributed within structural bays such that heavier soil loads were offset by lighter wood decking loads.
6” caliper trees were lifted into place by helicopter; the ipe decking was custom built to conform to the curves of the terraced seating and sloped walkway. This striking roof garden has contributed greatly to the transformation required to keep this 1950s property competitive in the contemporary office rental market. The 11,500 SF roof garden was completed in 2015 with a budget of $2.5 million.