PURPOSE: To enhance the waterproofness between a roof part and a wall part by fixing a lower roof cover engaging projection part and a lower roof cover placing part to a folded panel roof in parallel and fixing an adhesive waterproof sheet to the wall part.

CONSTITUTION: A lower roof cover engaging projection part 11 and a lower cover placing part 12 are provided to a folded panel roof 1 in parallel and the first and second adhesive waterproof sheets 21, 22 each fitted with release paper are fixed to a wall part 2. Next, the first adhesive waterproof sheet 21 is bonded to the lower roof cover placing part 12 of the folded panel roof 1 and the wall part 2 by releasing the release paper. Subsequently, the engaging part 32' of a lower roof cover is engaged with the lower roof cover engaging projection part 11 of the folded panel roof 1 and the second adhesive waterproof sheet 22 is bonded to the erected part 31 of the lower roof cover by peeling off the release paper. By this method, the waterproofness between building units can be enhanced.