Educating the Eye: Staircase Edition

Rooms are rooms, doors are doors, cabinetry in contemporary architecture, is still, just cabinetry.  But stairs are sculpture.  Stairs are where the design team are given the license to “do something spectacular.”

Stairs must meet code for safety.  Children must not be able to fall from the sides of them.  They must have handrails.  They must last during a fire.  But in New York City, they must also be spectacular.

The design by Haute Architecture for this stair was for a dramatic steel mono-stringer (a single piece of steel in the centre of the stair), that would travel from floor to floor, wrapped in concrete.

Concrete is beautiful, but the design team must accept its nature, which is strong in compression and weak in tension.  So, the steps would be strong as their load is compression as people step on them.  Concrete does not compress.  But on the underside of the stair, the stair would be attached point to point but then would be in tension between these points, like an electric line between poles.  To compensate for this tension, the design team designed a joint on the back side of the stair at each step so the concrete would be able to “pull apart” at the joint, rather than cracking.

Rusk asked Haute if this was the design intent of the stair: “Were these joints part of the aesthetic of the stair?” “No, they were a practical reality of the material.  The stair’s intent was an organic, even human form.  A stylized human spine on the underside of the stair.”

Rusk proposed keeping the concrete treads which were great for feet marching up them; but for the underside of the stair, Rusk proposed sheathing the steel mono-stringer with a high-tech material called Glass Reinforced Gypsum.  This fiberglass reinforced plaster material could be created in a factory using the architect’s computer design files.  The material is relatively lightweight and slightly elastic because of the fiberglass reinforcement which prevents cracking.  Each flight of stair would require three sheets of this custom GRG panels.  The sheets would then be seamed together to make a continuous form, and then the form was skimmed in decorative concrete to match the treads.

The stair is incredibly beautiful, is truer to the Haute’s artistic intent than the original plan, and four years later, the stair remains without a crack.

Design and Architecture: Haute Architecture DPC

Photography: Susan Fisher Plotner