The spiral stairs with curved glass railings in the foyer of the KfW Bank in Frankfurt combine design and aesthetic demands with technical and functional requirements. With an underside soffit of varnished steel sheet matched to the stairs flight run, this staircase possesses all the characteristics necessary to qualify it as modern architecture. The glass railings and the high-grade wooden handrails are a perfect combination.
The stairs structure consists of box-type stringers with folded stair flights welded in between them. The outer stringers have holes to provide indirect lighting for the steps. The evenly rounded stairs flight with a width of up to 1,400 mm integrates harmoniously with the architecture of the lobby.
The box-type stringers are welded from rectangular/H-sections and fixed with steel base plates to the unfinished floor. They hold the panes of the glass railings. In accordance with trends in modern architecture, the curved soffit lining was constructed with 5 mm-thick steel sheet.