A building (generally of two-story configuration) is divided into two parts at the midpoint, and one of the walls of each of the two parts, as in a row house, is shared by adjoining dwellings, thus economizing on land usage and the cost of construction.
1棟の建物（多くは2階建て）を中央で区分し、2軒の家が壁の一方向を共有する形式で、敷地や建設費を節約できる。