OSHA requires that handrails not be higher than 37 inches from the upper surface of the handrail to the tread. Also, handrails cannot be less than 30 inches from the upper surface to the tread. There is no average height due to so many differences in types of staircases.
All handrails must adequately provide a surface for people to hold onto to prevent falling. A handrail must also be able to withstand 200 pounds applied to it. If a stairway has four or more steps or is higher than 30 inches, a handrail is required. A spiral stairwell requires a handrail so people do not step on areas of it that have a tread of less than 6 inches.