concrete and steel.
The post tensioned stair had rather more humble origins; the concrete cantilevered treads of an earlier design were built so badly, they had to be redone. In a wild moment of contrariness, the client saddled the design with an added task of having the treads held away from their supporting side wall, effectively removing the continuous joint required for a cantilevered support.
To this end, it was realized that steel rods would have to work both as baluster and structural support for the treads. The stair was redesigned as floating wafers hung off wall anchors on one side and steel rods on the other, post tensioned with threaded locking cylinders at the base of each rod for lateral stability.
