PURPOSE: To have more latitude in a design for the arrangement of rooms by constructing a special house unit in which each joint between temporary columns and beams is made as a roof beam type and width alone is made to be smaller than that of the standard house unit, in parallel with the standard house unit.

CONSTITUTION: A frame 12 of a special size house unit 11 is composed of temporary columns 13, upper beams 14, 15 and lower beams 16, 17, its width W2 alone is made to be smaller than a width W1 of the standard house unit 2, and depth L and height H are made to be equal. Each joint between these temporary columns and upper beams is made as a roof beam type and each of upper beams 6 of the standard house unit 2 is joined to each outside end face of columns 4 as a continuous column type structure. Both units are then constructed in parallel in the building site and after these beams are joined to each other, the temporary columns 13 of the special unit 11 are removed. With this method, the construction cost can be reduced and latitude in a design for the arrangement of rooms can be enlarged by providing a large space in the unit house.