PURPOSE: To apply stable waterproof performance to roof construction.

CONSTITUTION: A first frame body 2 to be set on the water lower-side of roof construction is formed by integrating an angle member 4 and a channel member 5 with each other. The angle member 4 of the first frame body 2 has a waterproof sheet retaining section 6 with the terminal section of a waterproof sheet A to be mounted on, and a first setting section 11 to be embedded into a concrete floor surface B. Then, by driving B stud 26 into the waterproof sheet retaining section 6 of the first frame body 2 through a second frame body 3, the first frame body 2 and the second frame body 3 are fitted integrally and firmly via the waterproof sheet A.