According to the Occupational Safety and Health Administration construction guidelines, handrails installed after March 15, 1991 must be at least 36 inches high from the upper surface of the handrail to the surface of the tread. Handrails are also subject to other, stringent, specifications.
OSHA requirements for handrails are designed to protect the worker from injury and fully explained on its website. For instance, stairways with four or more risers must have handrails, and handrails must provide adequate handholds for employees to grasp to avoid falls. Handrails must not have protruding edges, as such an edge would cause injury during a fall.