The four floors in Daxing District of Beijing are all self-built houses. According to relevant data, there is a four-story building in Xiaonan Street, jiugong town, Daxing District, Beijing (the first to third floors of the building are brick-concrete structures, the fourth floor is made of colored steel plates, all of which are used for renting, the first and second floors are used for clothing processing and accommodation, and the third and fourth floors are used for accommodation, which is a typical "three-in-one" or "all-in-one" place).