PURPOSE: To enhance the safety of operations by a method in which couplers are attached to the base, one side of an assembled roof is connected to the couplers, and the other side of the roof is lifted up and fixed to a specified position.

CONSTITUTION: Auxiliary parts 2 are horizontally attached to the outer wall above the edge side opening of a base 1, and a caulking 4 is put between the water drain part 2a and the base 1 to prevent the intrusion of rain water from the aperture between the part 2a and the base 1. Roofing parts such as rafter hanger 5a, gable part 5b, beam 5c, and intermediate core 5d is assembled on the land and attached with roof panels 5e to make up a roof 5. The side of the rafter hanger 5a is lifted up, the projection 5f is connected to the hook 2b of the part 2, and the roof 5 is turned around the hook 2b by a winder 6 to raise it to a given height. The beam 5c is fixed to struts 7 set on the ground and attached with the roof 5. The safety of operation can thus be enhanced by reducing the frequency of high-level(height) operations.