3R Staircase

The spiral staircase at Bollinger+Grohmann's Stuttgart office is an example of circular principles being applied in the construction industry. This in-house project was used to explore how planning and manufacturing processes evolve when questions of necessity and availability take centre stage.

The staircase's structural design is based on the load-bearing capacity of the steps, which rest directly on the floor slab. To bridge the 3.23-metre floor-to-floor height, a staircase comprising 18 steps was designed. Given the open spatial structure, the optimal solution was a spiral staircase shaped like approximately three-quarters of a circle with varying radii and a slightly widened centre, as this keeps pathways clear and makes efficient use of the space. Clear radii and angles were used to define the geometry and ensure simple, straightforward construction.

The load-bearing stringers were designed as continuous curved surfaces that also serve as handrails. The timber structure was constructed from reused demolition beams. Preparing them placed high demands on workmanship and logistics, whilst also highlighting the challenges of circular construction processes.

The steps are also made from recycled materials: former table tops were reinforced with a concrete overlay to create load-bearing timber-concrete composite elements.