Flats corridors’ designs that are relatively narrow are less able to accommodate the needs of social space for residents in low cost flats. This is because Indonesian people are used to livinge in horizontal housing, one of them being the kampung. The kampung alley provides for various forms of dynamic activity and social interaction for resident, and make it to be a good social space. Related to this fact, architects have the task of designing flats corridors that could accomodate residents’ needs for social space such as the user’s behaviour setting in a kampung street. This issue is in line with the case study in Sombo Flat’s corridor which was designed based on the characteristics of a kampung street’s behaviour setting concept. With that concept, flats corridors were designed very wide, approximately 3–9 meters. This wide corridor give residents the opportunity for social interaction and other dynamic activities that take place in the corridors. This paper aims to evaluate the design implementation of the Sombo Flat’s corridors using analysis on behaviour setting method, which covers the pattern of the activities, setting/milieu, synormophy (the relationship between activity and the setting), and also analysing space usage patterns that occur in the corridors. The data are collected through observation, interview, documentation and analyze with descriptive qualitative methods. The results of the research show that Sombo Flat’s corridor, designed based on the characteristics of a kampung street concept, can accomodate the resident’s pattern of activities well, especially in the function of social space to create a sense of neighborhood. However, the negative impact from this wide corridor design is that it gives residents an opportunity to appropriate their personal space in the corridor which supposedly is a public space (thereby changing the spatial usage).