A free-standing cantilevered staircase in Shoreditch

ACME has completed a staircase prototype combining modern methods of construction with an adaptive design approach, created to work with a minimum of intervention within any building. The existing building had no usable stair between floors. A hole was first cut into the first floor slab to create a connecting void. It became clear during demolition that the existing first floor concrete slabs had no further load capacity, necessitating a new approach to the stair design. Rather than relying on connections of the stair at its top and bottom, the stair is designed as a free-standing cantilever, with no connection to the floor above.

Once the interlocking pieces for one step are assembled, they are simply fixed with screws to the step below. e stair was designed to be self-supporting during assembly, to ensure it can be build without scaffolding or temporary works, and all elements were designed to be light enough to be assembled directly by the designers. The bifurcating twin spiral form of the staircase serves a number of functions. The shape creates its own structural integrity, the bifurcation allows people to make destination choices on the stair, the widening of the stair provided a place to stop and converse, and the inward rake of the upper steps provides stability and functions as a handrail.