PURPOSE: To use the roof of a building, which has not been used, also for a room, etc., inside a building by making it into double construction with panels, making cushions between their intermediate layers with rubber system, and also providing air vent ports for absorption of shocks, etc.

CONSTITUTION: A frame is formed around the base part of a concrete panel 1, etc., with a rubber system 3. Also proper holes 4 (air vent holes) are opened partly in the frame. Then the concrete panels are land down on the floor of u roof, and their joints 2 are sealed with caulking, etc., to prevent rain water from entering.