The Occupational Safety and Health Administration (OSHA) has many regulations regarding stairs, stair railings and handrails. Most of these are covered in the 1910.24 and 1910.23 standards for general industrial areas. These standards apply to most but not all stair applications. Certain exceptions, such as stairs on floating tanks and maritime docks, do not come under the same regulations.
All stairways must be equipped with either railings or handrails. In the case of enclosed stairways, a handrail will be installed preferably on the right side of the stairs as you descend. For open stairways, a stair railing with a maximum of 34 inches from the top of the railing to the surface of the stairs should be provided. This height will also not be less than 30 inches from the top of the railing to the surface of the stairs. An intermediate rail will also be provided approximately half way between the surface of the stairs and the top railing.
The angle of the rise in the stairway will not be less than 30 degrees and not more than 50 degrees. Varying degrees of rise require different riser heights and different tread run distances. For example, with a 30 degree rise your riser will be 6 1/2 inches while your tread run will be 11 inches. On a rise of 49 degrees, your riser will need to be 9 1/2 inches and your tread run 8 inches.
The rise heights and tread width of the stairs must remain uniform for the entire distance of the stairway. The treads must be constructed of slip-resistant material while the nosing must be of nonslip material. Nonslip tape can be applied to the nosing to meet this requirements. Welded bar grating is also considered to be nonslip material. Any landing in the stairway will be at least the width of the stairs and will be a minimum of 30 inches in length measured in the direction of travel.
Stairways will have a minimum clearance of 7 feet from the surface of the stairs to the ceiling or other overhead obstruction. This is to ensure safe passage for the average adult. There are some exceptions to this requirement in the area of fire escape which do not require the same overhead clearance as normal pedestrian stairways.
Stairways will be constructed with sufficient strength to carry a load five times greater than the expected maximum load. For example, if you intend the stairs to hold a 90.7kg. man carrying a 29.5kg. load, your expected maximum load is 120kg. To meet the standards, you would need to construct your stairway with enough strength to hold 601kg. Regardless of your expected load limit, stairways are always required to have enough strength to carry a load of at least 0.454kg.