Stair strength: Fixed stairways shall be designed and constructed to carry a load of five times the normal live load anticipated but never of less strength than to carry safely a moving concentrated load of 1,000 pounds.
Stair width of fixed stairways shall have a minimum width of 22 inches.
Handrails are important: If steps are greater than 44” wide then handrails must be on both sides; less than 44” tread – only one side.
Vertical clearance: should be at least 7 feet measured from the leading edge of the tread above any stair tread to an overhead obstruction (so you don’t it your head).
Winding stairways may be installed on tanks and similar round structures where the diameter of the structure is not less than five (5) feet. However, usually shall not be permitted except for special limited usage and secondary access situations where it is not practical to provide a conventional stairway.
Angle of stairway rise: Fixed stairs shall be installed at angles to the horizontal of between 30 deg. and 50 deg.
