This Study is based on a living process survey of "Two-Step Housing System" . The Part-1 of the study clears the characteristics of floor plan and brings out following results: 1. Significant changes in living style after retirement and/or at the aged parents have occured in "Hikarigaoka". They are mostly new use of former children's room for study and/or hobby purpose, and also the separate sleeping. 2. Most families of "Tana" are middle age parents with growing children, and no significant change in room use has been observed. 3. Almost no change in the Infill arrangement has been seen both dwelling units.
