A goal of this research is to propose the remodeling possibility from deteriorated stock apartment housing, to three generation family living in a dwelling unit for low incomes. An apartment housing which was built from 1970s, is accumulated over $55\%$ of the stock housing in Korea, many of them are confront with a rebuilding in a short usage of twenty years below. They are small one, and many of the residence complain narrow and small space compare to economic growth and their needs. This article deals the reform of two to one dwelling units, that it can be use for three generation family living as a new residence, because its spatial character is more controled privacy condition as a four bay spatial organization in the dwelling. The reform simulated in a 10, 13, 14, 15, and 16 pyung, the remodeling size became from 20 to 30 pyung, and its reform can be apply to extend life cycle of a stock confront with redevelopment. The possibility of the reform houses have more intensive privacy in a house compare with same area of new apartment. It tells us that we can recycle the deteriorate apartment house into three generation family living use, and it will be clue to change slum clearance into reform and recycle of deteriorate apartment house.