Abstract
In suburban detached housing development site in a provincial city, some families expand their housing lot gradually by combining neighboring lots. This paper clarifies the process of these expansions. the following are our major findings. 1) The direction of lots expansion is related to direction of streets adjacent to the first owning lot. 2) The major reasons of expansion are to live together with their children's families, to prepare space for their cars, and to secure land when the land price is low. Some families even own lots that are not neighboring to their original housing lot, and they lease it or use it temporally. 3) Most residents welcome vacant housing lots, but they wish to be well cared.
