The roof of the three-storeyed residential building from the 19th century should be rebuilt and extended to an apartment. For geometric, static and building physical reasons the extension was not realizable with the existing roof construction. For that the roof timbering was removed completely and rebuilt in form of a pitched roof. To align the geometry of the roof space for residential use the ridge line was raised but subordinated to the neighbor building. Despite of this elevation the roof surface areas stay not visible from the street. Generous roof-top windows in direction to the street care for lighting and ventilation of the new living area. On the roof side to the courtyard a row of little roof-top windows was planned to light up the depth of the rooms. The construction of two dormers with in front of lying terraces was another of the rebuild measures their result was a light, friendly and modern apartment.