Montagu

The heritage context of the stair necessitated a complex design that makes minimal contact with the walls. In response, our structural team helped develop a steel plate design 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 listed building’s wall, using the fanning triangular steel plates to provide structural depth and stiffness.

The stair was pre-fabricated and brought to site in sections, then assembled and welded together to create the final form. 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. The welds that were on show were full penetration fillet welds, 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 the wires for the integrated lighting.

The result is an elegant sweeping form where every plate and weld is considered and appreciated.