As part of the modernisation of a house in Cologne, the cellar was converted and access provided via a single-flight steel stair leading from the ground floor. The top three steps have wooden treads on a concrete base and are built into the vaulted ceiling itself. The filigree steel of the remaining nine steps contrasts with the solidity of the ceiling, the wooden treads continue the flooring theme from above. The stair structure was designed to be adjusted on site, to take up tolerances and enable exact positioning of the steps. The steps are fixed laterally to the trussed tubular steel stringers via threaded tube connections; at the back the steps are joined by a cross piece and held in position by a steel disc.