| 摘要 |
PROBLEM TO BE SOLVED: To provide a staircase unit in which a riser is prevented from being warped even while forming, in the riser, a shape such as e.g., a recess or a rib to make the riser into an uneven surface.SOLUTION: A staircase unit 1 is configured by integrally molding plastic and comprises: a tread part 2 which is plate-shaped; a riser part 4 which is as wide as the tread part 2 and droops downwards from a front end 2c of the tread part 2; and a rising plate part 3 which is as wide as the tread part 2 and rises upwards from a rear end 2b of the tread part 2. On a front face 4a and a back face 4b of the riser part 4, uneven surfaces are formed in which repeating shapes of triangular waves are formed in series, at equal intervals and without gap as planar shapes, respectively, and disposed in such a manner that a back-to-back positional unevenness relation between the front face 4a and the back face 4b becomes alternate, thereby fixing thickness of the riser part 4. |
