The usage of social theories in the human-built environment caused to enhance life quality. It may consist of human needs in residential areas. Sometimes, building codes can help to exist accepted life space, but the building codes do not have basic theory such as actual open space in residential plots. The study was an attempt to represent a new approach in urban land subdivision and the relationship between social theories and built up area. The research question was how to determine the open- space ratio. Main indicators were related to residential areas in urban areas in Iran which the lot size and urban density appear. The study tried to represent optimum open- space ratio based on Edward Hall's theory. The method was based on mathematical model and social theory. Finally, it resulted in optimum OSR in lot and it was not enough open- space ratios in existing situation. This study came to this conclusion that existing open- space measure was not enough for any Lot in new residential areas based on mentioned theory. In addition, investigation showed that the human distances effected on open and built up space ratio in a new residential layout. It was concluded that every residential area can have an optimum open- space ratio based on its situation. The results can use new residential layouts for enhancing human-built environments, but it noticed that there are not certain tools for making high-quality environments based on social theories.
