Zahner worked with the architects at Diller Scofidio + Renfro to develop a gliding red staircase for the recent renovations at The Juilliard School in New York City. Zahner was responsible to Turner Construction in New York City for producing the design engineered metal-work. The two staircases are located one after the other, on the eastern-most side of the school from the third to fifth floors. There the students can collect their thoughts around the adjacent study areas.
The staircase was designed to appear as though it were made from a single sheet of metal. In actuality, the stair is made possible by several plates of 3/4" mild steel, seamlessly welded and painstakingly ground to achieve the look of a unified single piece of metal. Each step is a separate plate, bent at a 90 degree angle on either side, and then welded to either side of the staircase. The stairs are placed at a non-standard height and depth, so that the effect is a "slow staircase" where each step is only slightly elevated from the last.
One of the issues with welding metal is its tendency to warp itself towards the weld. When it came time to weld the long pipe which serves as the hand rail, Zahner identified this as a potential problem. If this wasn't done correctly, the entire staircase would bow to the left or right as one looked up at it. After debating different ways to prevent warpage, the solution Zahner employed was an old ship building technique -- we welded the handrail from both sides at the same time. The result is a highly accurate straight piece of steel with only three connections to the building.