| 摘要 |
PURPOSE:To provide convenience by a method wherein a space under an outdoor stair is not wetted with rainwater, and the space is utilized for a bicycle parking yard and a closet. CONSTITUTION:The upper surface of a tread-board 2 of an outdoor stair forms a slope, a drain groove 3 is formed in the side edge part of the tread-board 2 of the lower part of the slope in a state that the drain groove is inclined from a part situated deep therein to this side, and the tip part on this side of the tread-board 2 at an upper stage is protruded to a position above the tread-board 2 at a lower stage. When rain falls, rainwater falling on the tread- board 2 of an outdoor stair flows rightward and leftward along the slopes of the tread-board 2 and flows in the groove 3 of the tread-board 2. Further, the rain water flows through the groove 3 in the direction of this side, and is dropped downward from the groove 3. Further, since the tip part on this side of the tread-board 2 at an upper stage is protruded to a position above the tread-board 2 at a lower stage, rainwater dropped from the groove 3 is dropped in the groove 3 at a lower stage. As noted above, rainwater is dropped to the tread-board 2 at a lower stage one by one and finally flows to the root of the outdoor stair. |
