With a curved glass railing and a curved underside soffit, the spiral staircase in the Prediger light shop in Hamburg is a perfect example of innovative stair architecture. A glass railing must comply with the currently applicable regulations of the Technical Rules for the Use of Fall Protection Glazing (TRAV). Developing a glass railing that complies with these regulations requires expert knowledge.
With this type of glass railing, the panes freely jut out from the bearing structure without any disturbing posts. The bearing structures of the inner and outer railings are the supporting stringers of the spiral stairs at the same time. The balustrade panes consist of two laminated safety glass panes that have been thermally pre-tensioned and are held together by a PVB film. The glass thickness and the rail load of the handrail are calculated in accordance with the TRAV rules that apply to any type of fall protection glazing. 20 mm-thick laminated safety glass panes are used to ensure compliance.
The glass panes of the glas railing are fastened in the bearing structure with the help of a casting method that meets inspection standards. When inserting the glass panes with the specified method, no laborious wedging is required.
Handrails for glass railing
The stainless steel handrail is made of a rolled circular steel tube with a diameter of 48 mm and is fixed to the glass railing with an intermediate layer of neoprene. It complies with structural requirements.
Construction of the spiral stairs
The only reason why this staircase was designed with box-type stringers (welded rectangular H- steel sections) is that they are needed as supporting structures for the glass railing. These stringers also offer benefits with regard to structural requirements.
Folded steel stair treads providing the substructure for the tread cover are welded between the box-type stringers. Another decisive element of the impressive stair architecture is the plain underside soffit.
With an inner diameter of 2,200 mm and an outer diameter of 5,600mm a generous flight width of 1,600 mm is obtained. The staircase design complies with the regulations of the construction authorities concerning glass railings and with DIN 18065.
The free-standing spiral staircase in the showroom is self-supporting. This means that all forces are borne by the floor slab underneath and above. Additional fastening to walls or support by columns is not required.