Representative spiral staircases
Roche-Tower in Basel
The complex staircase and railing ensemble made of steel and glass that MetallArt realised for the new headquarters of Hoffmann – La Roche in Basel prevailed in the category Staircases and Railings and was awarded the German Metal Construction Award 2022.
On 4 November, the jury announced the first-place winners in a total of six categories at the evening event of the Metal Congress in Kaufering. The national competition, in which the stair construction company from Salach already succeeded in 2016, has been organised by the specialist magazine M&T Metallhandwerk & Technik for 10 years now and awards prizes for outstandingly executed projects in the metal industry.
Elaborate structural and constructive design
The winning project in the new office tower of F. Hoffmann – La Roche AG at its headquarters in Basel extends over 45 of the total of 50 floors in Switzerland’s tallest building with a height of 205 metres. It consists of 16 highly elaborate spiral staircases of six different types, which differ in storey height, running width, number of risers and stair layout. Parapet-high all-glass railings on both sides continue with transparent gallery railings at the rounded slab openings and are complemented by elegantly curved wooden handrails featuring a filigree look. Despite the immense amount of steel used, the centrally installed stairs blend gracefully and dynamically into the light-flooded interior. “We are absolutely proud to receive this recognition for our achievements and pass on our thanks to our dedicated team, which enabled us to carry out this project so masterly,” said the delighted MetallArt managing director Andreas Wahsner after the award ceremony.
Highly complex design
Sophisticated staircase architecture
The ambitious system was developed in close cooperation with the renowned architectural office Herzog & de Meuron from Basel and the successful general planners from Drees & Sommer and, like the entire building complex, was realised by using only sustainable building materials and processing methods. Various constructive features and creative details were executed by MetallArt with expertise and skilled craftsmanship and create a harmonious interplay of design and material. The ascending inner and outer stringers of the steel stairs show varying curved radii and heights and pass flowingly into the steel frames of the slab openings. These transitions called for extremely elaborate constructive solutions. The design of the curved all-glass railings for the staircase and gallery balustrades, which MetallArt adjusted and fixed to the stair stringers and ceiling frames using specially developed methods and sophisticated assembly methods, is equally exclusive. In order to manufacture the extremely narrow bent radii of curvature at the sections between stairs and ceiling railings and to comply with the structural requirements, glass panes made of extra-white float glass with Sentry film were used. A pendulum impact test had to be carried out to allow the extra-long individual panes to be approved. MetallArt constructed the recessed steps as a folding structure and welded them between the stringers. The smooth-surfaced steel soffit, as a structurally supporting element, lends the steel staircase stability and a sculptural character. For this purpose, MetallArt welded precisely shaped steel sheets according to the curvature of the floor plan and the varying heights of the lower stringer edges flush between the stringers.
For all of the balustrades, the woodworking family business HolzHacker from Göppingen produced the handrails in solid oak, bent in different radii and glued in several layers. These handrails were attached directly onto the glass panes as an elaborate custom-made product.
With state-of-the-art technology and logistical expertise, the MetallArt team managed to solve the challenges during the 3-year installation phase: In the densely urban area of Basel, MetallArt delivered the prefabricated stair segments “just in time” due to the lack of storage and installation facilities and inserted them directly into the building by means of construction cranes. Many years of project experience and technical precision enabled the following assembly of the steel stairs and all-glass railings, which can be found on almost every floor in the office tower.