Stair Riser Too High . A stair stringer is a structural member that supports the treads and risers of a staircase. As we explained above, the most common stair riser defects likely to lead to a fall include: Mono Stringer Staircase Demax Arch from www.chinaglassbalustrade.com Most of the time, when your stair is going from one platform to another, the riser height is determined by the overall height difference. Osha 1910.25 (c) (2) requires standard stairs to h ave a maximum riser height of 9.5 inches (24 cm). The height of the stair should be reduced by 1 to 2 inches.