A unique view across the city of Zurich and its environs awaits those visiting the restaurant in the new storeys of the “Hochhaus zur Schanze”. The new storeys were constructed by transferring the loads consistently to the structural core of the 1960s building complex across the five storeys below them.

The concrete core was extended by two storeys and supports the steel structure of the extension. The ceiling slab above the “arrivals deck” is supported by solid steel beams in the restaurant roof. It is connected to the beams via tension bars in the façade. A slender three-storey shaft, which also has a steel supporting structure, houses the building services equipment. The use of composite slabs made of lightweight concrete ensured economical construction and minimised the loads applied to the existing structure.

Special investigations were carried out to determine the complex deformation behaviour of the structure, in order to prevent damage being caused to the façade elements and fixtures.