The late-19th-century residential building in Zurich’s Seefeld district was to be renovated and optimized while maintaining the existing leases. The client requested a comprehensive remodeling concept that could be implemented in stages. Initial renovation work began in 2007. The main intervention consisted in adding a residential unit in the attic space, which required adapting the shape of the roof. The existing attic roof provided the “grammar” for the new roof with a terrace. Derived from the construction principle of an igloo tent, a support-free roof space of 100 m2 (10 m by 10 m) was created with tension cables in the floor.

The heating system was replaced and combined with a new solar system for eco-friendly water heating. The building services were moderately updated where needed. The existing apartments remain largely intact, apart from necessary modifications to the hot water distribution network. For fire safety reasons, the apartment doors were overhauled, and the stairwell received a deliberately dark color scheme to contrast with the bright living spaces.