This paper develop the distinction between two concepts : appropriation and utilisation of dwelling family's space. The first is defined us a psychoso cial fact that comprised all particular's use behaviours in the dwelling, that let transform virtual space in concret, personalized space. The second is defined as the habitual realization in time and determinated places, of the required activities to inhabit dwelling in a practical way. Those activities it integrate and could make sense in the particular use's behaviours. It states the different stages of family's appropriation of space in time, creating a relation these concepts with the evolutive family development and with the familiar economic changes. The results to obtain through the described method, leads to some concret suggestions to the designers of public dwellings.