Unclouded marble shine - thanks to invisible fastenings

The design was created by the Zurich architectural firm Office Haratori and the architects of Office Winhov from Amsterdam. The planners succeeded in expressing the client's field of activity also in the architecture. The renovation of the building and the newly executed marble facade in 2017/2018 integrate the commercial building into its surroundings. In addition, the renovated commercial building simultaneously represents solidity, timelessness, innovation, and perfection—the "core business of the Bucherer company," according to the architects. While the ground floor is entirely dedicated to the material bronze, the carefully arranged marble slabs characterize the upper floors. The stone comes from the only marble quarry in Switzerland, located in the canton of Ticino. "We refine the marble from the Vallemaggia into precisely crafted, jewel-like elements," says the Office Haratori about the design. "The facade becomes—similar to a sundial—a reflection of the ongoing daily and seasonal changes. The marble relief appears in the changing shadow play, sometimes softly flat, then sharply defined and orderly."

The facade consists of approximately 100 different steel tube lattice structures, equipped with conically tapered marble pieces ranging from 6 to 18 cm thick in various sizes. These components were prefabricated into elements in the factory. Later, they were hung on site in blind assembly on 6 to 8 pins. The individual weight was up to 4.5 tons. Placing such heavy elements with a non-centric center of gravity so precisely that all pins are hit was a great challenge. Especially since the steel elements were not flat but deformed up to 10 mm, which is unavoidable in steel construction. Only with a suspension device specially designed for these elements could this hurdle be overcome. The business unit fischer Facade Systems of the fischer Group was responsible for fixing the marble slabs onto the steel structure using undercut technology. The undercut holes were drilled with a tolerance of less than 1 mm. This meant considerable effort, as Steven-Henrik Maier, Market Manager of fischer Facade Systems, reports. "Challenges arose regarding the high loads due to the weight of the slabs, which were up to 180 mm thick. Several pull-out tests were necessary to prepare for correct and safe execution." The tests were carried out with different slab thicknesses (30, 40, 60, 80 mm), also near the edge and with larger slab formats. As a result, to be able to transfer the loads, a special anchor with greater embedment depth was designed.