This project combines three apartments on the 15th and 16th floors of a postwar coop building on Fifth Avenue in Manhattan into one residence. A new staircase provides internal circulation between the floors. It is located within the exterior setback portion of the building. The elliptical shape of the stair is defined by the curvature of most comfortable travel possible within the smallest space affordable, in order to minimize the zoning encroachment of the overall building envelope.

The steel staircase was developed in collaboration with the New York office of Werner Sobek. It is supported by a central stringer and flanked by free spanning handrails that are made from custom Z-profiles. A glass envelope facing the Guggenheim Museum and Central Park encloses the stair. It consists of curved load-bearing insulation glass that stands by itself without any metal support over the full height of two floors. It is the tallest structure of its kind that has been built to date. Stair and enclosure were prefabricated in Germany and lifted into their final position on site by a telescope crane.

Type: Built
Place: New York
Year: 2007-09, 2019
Collaboration: Georg Windeck, Peter Schubert
Team: Wanlika Kaewkamchand, Werner Sobek (structural), Ettinger Engineering (mechanical), Sandy Lindenbaum (code consultant)
Photos: Tom Crane