Location: London
Date: 2017
Client: ACME
Status: Completed
Size: 6 m²
Credits: Structure: AKT II
Timber: Blumer Lehmann
ACME TEAM: Friedrich Ludewig, Eleni Meladaki, Sara Poza Ruiz, Charles Pigott, David Rieser, Jan Saggau
A staircase to get from ground to first floor. Designed over 48 weeks, manufactured in 4 weeks and constructed in 5 days. The stair consists of 120 pieces of cross-laminated timber crafted by a 5-axis CNC joinery machine directly from our 3d model, permitting the prefabricated pieces to be transported and puzzled together, interlocked by milled dowelling and adhered with an epoxy glue.

The stair uses the shape of a spiral to nestle into an irregular shape in a corner, while hugging a structural column. This transformed into a free-standing bifurcating double spiral stair that combined the travel routes between different spatial functions of the studio. The unique form offers many opportunities. Its structural integrity allows it to be self supporting; the treads raked inwards to provide a nominal handrail.

The economical use of timber was paramount, minimising the structural depth of the tread for an optimum cantilever that deftly manoeuvred the stairs shape to occupy regulatory head heights. As a result the tread length was gradually reduced in the stair climb utilizing both structural and spatial conditions that informed the design. The stair has been a useful in-house prototype to test methods of assembly and construction, showing one way to use mass timber as the main structural material and minimizing the embodied carbon footprint of a building.