Stairways to design efficiency

Phil Waind of Waind Gohil + Potter Architects describes how the firm has developed a ‘design for manufacture’ approach to optimise the creation of staircases as a key element of buildings for users.

Waind Gohil + Potter Architects believes it’s not just what it looks like, it is how you design it that counts. We are particularly interested in design for construction/fabrication processes, or as product designer would term it, ‘design for manufacture,’ where the design optimises procurement and manufacturing processes, assembly and testing, delivery and use.

Taking this principle and applying it to the design and construction of buildings excites us – it broadens design optimisation to include site context, planning, statutory regulation and appropriate construction process. We retain the key influences of fabrication, assembly and material efficiency to deliver the best possible outcome at the best price.

In this ‘design for manufacture’ context, stairs are a particularly important structural building element, with a close experiential/tactile relationship with building users in achieving vertical circulation, and visually, as an object within space. Stairs should be expressive of function and the process that makes them, as well as being appropriate to their context.

The design for fabrication of the bespoke stair has become a key thread of work and research development within our studio. We’ve established a rigorous design process, whereby the constraints and opportunities of a stair construction are established and rough concept sketches are tackled with our go-to structural and fabrication consultants, Webb Yates Engineers and Pipsqueak Developments. At this initial stage the appropriate fabrication processes are identified, and as the design is developed, reduced scale physical models and 3D CAD models are constructed, before full scale prototypes of sections of the stair are tested.

Staircase studies

Recent stair designs for three different residential projects in London demonstrate our approach and the advanced outcome of this research. For the Ardilaun project (a private residential conversion in Islington), the stair design was evolved whereby identical laser cut/folded steel pieces form the handrail and balustrade, appearing to cantilever but with each interconnecting. The efficiency of repetition of identical components and the visual trick of connecting them provides a rhythm akin to that of the adjacent timber Victorian newel and balusters and a sense of lightness. The use of a natural material, waxed raw steel, is in keeping with the honest use of finishes elsewhere, and the cost was comparable with a proprietary timber stair.

A staircase in a Grade II Listed building, Montagu, in Marylebone, central London was not as constrained by economics, however the Local Planning Authority dictated that the stair could not touch an adjacent listed wall. The logarithmic curved form of the string provides the structural integrity, from which the treads are cantilevered. The string and treads were again fabricated from laser cut and folded steel, forming a complex steel plate structure where each element is used to add support and stiffen.

The handrail forms the main support using the crossing lattice of vertical and horizontals to span like a beam between the floors. From this the treads cantilever out towards the wall, using the fanning triangular steel plates to provide structural depth and stiffness. The tapered form of the treads, which are under lit, and elegant lattice form of the balustrade take reference from the Georgian detailing and fenestration of the existing house.

The stair was pre-fabricated and brought to site in sections then assembled and welded together. The steel plates were set out and overlapped to allow the majority of the welds to be on the back edges, hidden from direct view. Full penetration fillet welds were visible but subsequently ground down to leave a neat, crisp edge.

Every detail was discussed and refined with the fabricator to ensure buildability and structural integrity, including a concealed slot to hide wires for integrated lighting. The treads were inlaid with oak, and sections of white leather clad the hand rail, albeit it was suggested that an anaconda skin would not require stitched joints!

Lastly, Frithville, a private residential conversion in Shepherds Bush saw a stair fabricated from Tintab plywood within a light stair well space with generous roof lights. The solid ply wood treads and balustrade/stringer provide a sculptural form, with the lamination of the plywood sheets expressed including a twisted interpretation of the newel post.

We continue to push boundaries with our research and development of stair design and fabrication with new findings, including material efficiency and the appropriateness of different fabrication process in terms of logistics, context, acoustics, function, and form.

Perhaps the most satisfying outcome is the realisation that designing for fabrication yields the unique decoration and elegance that characterise the completed installation via the fabrication process itself. This seems an appropriate, modern progression from the craftsmanship of the skilled wood turner and their lathe.

Phil Waind is a founding director of Waind Gohil + Potter Architects