A small Parisian duplex apartment, the project is focused on respecting the reduced dimensions of the place. Resizing, giving an element a multiplicity of functions, maximizing the light input, simplifying are the themes that dictated our intervention. Our project rehabilitates the East-West double orientation which allows a constant and diffuse natural lighting, giving a greater sense of space. This simple action demonstrates a place can be completely transformed by the use of light. The main part of the project restores access to the attic, where two rooms are set up. In the volume created by a doubled height, a game of pistons forms two staircases with alternating-step stairs concealing closets. The closets/steps are grouped or carved depending on the functions necessary for every room (Music, TV, Bookcase, dressing). Creating a staircase with such functionalities was essential to avoid reducing the available space.