PIPING STRUCTURE FOR DRAINAGE

PROBLEM TO BE SOLVED: To provide a piping structure for drainage which allows cutoff means to be easily installed at a proper position on the downstream side of a sheath pipe and a downstream joint, even for a change in the length of the sheath pipe.SOLUTION: A sheath pipe 11 embedded in a foundation part 5 of a building 2 includes a downstream end passing through the building 2 to the outside and an upstream end passing through an underfloor space 3. A small diameter pipe 12 is inserted through the sheath pipe 11. An upstream joint 13 of which at least a portion can be inserted in the sheath pipe 11 connects the upstream end of the small diameter pipe 12 to the downstream end of a drain pipe 6 inside the building. Furthermore, a downstream joint 14 at least a portion of which can be inserted in the sheath pipe 11 connects the downstream end of the small diameter pipe 12 to the upstream end of a drain pipe 7 outside the building. The downstream joint 14 includes a joint body 25 with an outer peripheral surface to which a downstream packing 31 can be fitted. The joint body 25 includes a plurality of positioning steps 26, 27, and 28 which prevent the downstream packing 31 fitted to the joint body 25 from being moved in the axis direction.