This converted detached house stands close to Basel’s historic Spalentor (Gate of Spalen). Dating back to the 1880s, it was originally an outbuilding belonging to a larger property that also included a villa, now demolished. A large stone wall divided the interior into stables and coach house on one side and servants’ quarters on the other. When a new building was constructed on the site of the old villa at the start of the 20th century, the outbuilding was reinvented as a workshop. It has now been converted into a family home.

Dark and divided into a number of small rooms, the building needed major work to transform it into a comfortable, light and airy home. A round opening two stories high was cut into the stone dividing wall and new windows and skylights were created to let in more light. The existing load-bearing structure and walls were clad in concrete, cast on site.

The new concrete load-bearing structure with its striking columns and beams gives the impression of an over-sized table, its prestressed main girders are supported midspan along the length of the building by the arch action of the interior stone wall. The cross-spanning ceilings of the ground and first floors are designed as timber beam constructions. Inside the building, retrofitted steel transfer beams take over from the original walls. Once the new cellar wall had been cast, the existing strip foundations were reinforced by underpinning around the new cellar steps and by stabilizing plates elsewhere.

Self-supporting vertically, the facade was tied into the new load-bearing structure to provide stability against horizontal loads and the dimensions of the window openings were increased. Following the conversion work, both the interior brickwork and the support openings in the quarry-stone walls continue to serve as bearing members. The building has been reroofed in slate and generous openings have been made in the side facades to house double sliding doors, whose lintels and integrated guide rails project beyond the main facade into the garden space.