Seagrams stair marks Vector Praxis’ return to NYC

Seagrams stair marks Vector Praxis’ return to NYC

Curvaceous, model-coordinated stair marks Vector Praxis’ return to NYC

In December 2014, Vector Praxis staff and subcontractors finished work on a finely-detailed, model-coordinated feature stair which connects the 23rd and 24th floors of the Seagram’s building in NYC. This is the first stair job completed by the Vector Praxis team since we re-entered the architectural fabrication market in NYC.

The elliptical, spiral stair was designed in 3D by Vector Praxis, in collaboration with Gensler. The design complements existing curved Corian workstations and stainless steel panels.

The delicate, continuously-curved forms presented a number of detailing and fabrication challenges:

  • To reduce disruption of the client and other tenants and improve the schedule, the stair had to be fabricated offsite, then “assembled” at site.
  • The stair, an adjacent two-story feature wall and the fascia of the opening are all covered in curving, seamless, thermally-bent Corian sheet.
  • The handrail is continuous, mirror-polished stainless steel on minimal standoffs and was rolled using our new Tauring roll bending machine with helix attachment, then fit, welded and polished in house.
  • The full height, seamless Corian guardrail is only 2” thick and slides down over a ¾” plate stringer, leaving only 1/8” clearance between steel and cladding, which required high precision at all phases of the work, including steel fabrication.
  • To achieve this precision, the steel structure, glass shoe, fascia framing, back wall framing, Corian cladding, and mirror-polished handrail were all fabricated in a 1:1, model-coordinated fixture we call “the big jig”, ensuring a perfect fit at site with no cutting or trimming.
  • Zodiaq treads were cut to model dimensions using CNC process.
  • The shoe for the glass upper guardrail, the fascia framing and the pour stop were integrated in to a common segmented precision assembly which installed in a single shift, instead of the multiple weeks that would have been needed to coordinate 3-4 trades.
  • Curving, assembling and pre-cutting the Corian sheet required the fabrication of a $100K 1:1 pattern the same size as the central volume of the stair.
  • The steel spine of the stair had to be divided in 9 segments to fit in the elevators. The sections were assembled with lap splices held together by high-strength, fine-threaded flathead bolts which ensured perfect geometry and a slim profile.
  • The stair was assembled at site over a copy of the 1:1 plot used to control layout in our shop.

More about the Seagram’s Building

This historically listed tower is located on Park Avenue just north of Grand Central Station. It was designed by Mies van der Rohe, completed in 1958 and is widely considered to be the world’s first modern office building. According to Severud Associates, the structural engineering consultants, the Seagrams’ building holds the following records:

  • First tall building to use high strength bolted connections
  • First tall building to combine a braced frame with a moment frame
  • First tall building to employ a composite steel and concrete lateral frame
  • One of the first tall buildings to use a vertical truss bracing system