This private residence was revisioned to embrace the surrounding woods and tranquil hillside location while also offering city views of Stuttgart from a new upper floor. In place of a double-pitched roof, a simple yet structured, open-plan floor is realized atop the house, a building from the 1930s, which had been previously refurbished in 1990. The architectural idea was to place a deliberately unobtrusive structure upon the existing building. The second floor addition stands in contrast to the massive lower level without dominating it, creating a focal point for the house via massive glazing and without disturbing views of the surrounding landscape. The structure’s cantilevers on the south and west sides of the house place emphasis on the new addition and function as dividing elements between the existing structure and new roof system. Simultaneously, they function as canopies, creating covered areas for the garden. The position of the new volume – the “glazed box” – is a response to building regulations and a solution to differentiate each garden on the sides of the building, orienting them toward the sun and views. The location and organization of programming for the two lower floors are kept unchanged. The top floor has its own organization. The approximately 150m² open-plan space is zoned by “boxes” – the intimate private rooms used as a dressing room and bathrooms. A large sliding door divides the upper floor from the master suite and the guest areas with a lounge, inner stairs, a library, and a home office. An outside staircase leads up to the top of the new flat roof, where a new terrace is created. The result is a generous residential level that responds to the hillside and provides views of the city. In contrast to the glazed, geometric facade, the interior finishes create an inviting, relaxed atmosphere. The floor and walls of the private rooms are clad in walnut panels, evoking a quiet warmth with unobstructed surfaces that hide doors, cabinetry, and a built-in entertainment system. Upon entering the bathrooms, the atmosphere changes. Walls are dark and simple, and bursts of color in the furniture, cabinets, and fixtures are set as counterpoints. The dressing room is also different: white wooden cladding on the walls and moveable wooden shutters along the façade create a distinct character. The dimmable LED lighting system was designed with recessed, moveable spotlights, and additional lighting can be added when needed. The load bearing capacity of the home’s foundation and walls was unknown. Therefore, prefabricated laminate timber was used as a lightweight solution to construct the new top floor, creating an additional weightload that only marginally exceeds that of the home’s former roof structure. Floor to ceiling windows in wood framing shape the light throughout the upper floor, providing panoramic views and a sense of transparency. Exterior metal mesh roller shutters offer a filtered view of the surrounding landscape while protecting interiors from solar overheating. Radiant panels line both ceiling and floor and serve to regulate the home´s interior climate by cooling it in summer and heating it in winter. Radiant heating and cooling systems are further enhanced by deep probe geothermal drilling (3m x 90m), and the installation of a heat pump and solar thermal panels on the roof. The home’s existing gas heater acts as a back-up system.
The Stuttgart-based practice known today as Behnisch Architekten was founded in 1989 under the leadership of Stefan Behnisch. Originally established as a branch office of Günter Behnisch’s practice Behnisch & Partner, it became independent in 1991 and has subsequently developed into an international practice with offices in Stuttgart, Munich, Los Angeles/California (1999 – 2011), and Boston/Massachusetts. These offices are directed by Stefan Behnisch and his partners Robert Hösle (Munich), Robert Matthew Noblett (Boston) and Stefan Rappold (Stuttgart). Stefan Behnisch is involved in all three offices. From the outset, the social dimension of architecture has been a fundamental aspect of the firm’s design philosophy. The search for innovative and sustainable solutions making optimum use of natural resources has produced a rich variety of buildings, each of which responds to specific user requirements and site conditions.