n a backyard in Neukölln, we removed the roof from an old five-story factory building and created a new 250-square-meter unit with a roof terrace. The existing building consists of a side wing and an almost square transverse building. This T-shaped floor plan structure creates two backyards. It is accessed through the existing staircase in the second courtyard in the side wing and through an external elevator on the transverse building. The second existing staircase in the first courtyard only serves as the second escape route but is also conceivable as an access route.