Replacement of an existing spiral staircase as part of the refurbishment of a duplex flat at level 16 of One Osnaburgh, a residential tower built by Terry Farrell in 2010, located next to Regent’s Park.
We worked with the original interior architects, Johnson Naylor, to create a bespoke staircase for the apartment.
Site constraints included access for materials up to level 16, fixings allowed only to floor slabs as walls were party walls, load capacities of the existing slab and space available for structure.
Architectural requirements included no visible support to treads, no visible fixings and no cladding to structural steelwork. Aluminium balustrades to be coordinated with the stair structure and a fretwork aluminium screen to work as a balustrade. Each tread and riser is formed from 6mm folded plate. Around two sides of the staircase, each tread/riser plate cantilevers from a 90mm deep box section around the perimeter, with a fixing to the neighbouring plates. The posts are fixed to slabs at the head and base. Along the third side of the stair, the tread/riser elements cantilever from box sections that hang from a 203UC beam, fixed to the slab edge at each end. The beam is tied back to a slab edge along its length, to avoid torsion in the beam. The balustrade is formed from 10mm thick aluminium, connected to the riser plates.