This projects aims to renovate one of two apartment inside a two-story residential building in Cagliari. The client owns the apartment, with a total area of 173 sqm, with the living area on the Ground Floor and the Sleeping area on the First Floor, which were connected with an internal stairs. The goal of the project was to divide this apartment into three differents ones, by removing the internal stair and by using the shared stairs to reach the first floor. Moreover according to the Sardinian law «L.R. n°. 8, 2015» it was also possible to partially increase  the new apartment’s volume at the 1st Floor, by occuping a part of the balcony. In order to save money the apartments were designed by keeping all existing windows and adding only the required new ones.