Different options are analyzed for a tenant-owner living in a top-floor apartment in a multi-family house to furnish the attic into a maisonette (giving a two-storied apartement), to achieve more housing space. This degree project aims to demonstrate what technical and general conditions that are required while furnishing an attic into a maisonette apartment, in a building from the 1950s. Current general conditions that will have a significant impact on the attic reconstruction are considered, including: building construction, fire, daylight, installation requirements, construction, and accessibility. This work also examines detailed plans for the building and associated legislation that will have an impact on the reconstruction. The primary goal of the degree project was to develop three draft drawings for an apartment located on Agnegatan 2B, Västerås. The drawings could be the basis of a construction license application for a maisonette apartment. The authors had a presumptive costumer to take into consideration while working on the drawings. In addition, the authors made three visits to the examined apartment located on Agnegatan 2B. Further investigations were made on the apartment building’s detail plan and the authors discovered that it is formally prohibited to furnish the attic. To get a qualitative verification and analysis of the three proposals, an interview was conducted with a building inspector named Stefan Andersson, from Västerås municipality. During the interview the authors and Stefan Andersson made an exchange of views regarding an alternative solution despite deviation from the detailed local plan. When furnishing an attic and turning it into an maisonette some complexity may arise regarding the interpretation of the local plan, the building construction and some functional requirements. The interpretation may differ from municipality to municipality. Perforation of the building floor to install a staircase is one of the technical complications that may arise during a reconstruction of an attic into a maisonette apartment. One advantage with furnishing an attic into a maisonette apartment is that accessibility requirements only need to be met on the entrance level. Even though the local plan states that it is prohibited to furnish the attic on Agnegatan 2B, it may be possible after the case has been processed according to Stefan Andersson.