Stairways shall be not less than 36 inches (914 mm) in clear width at all points above the permitted handrail height PHOTO 1 & 2 and below the required headroom height PHOTO 2. The clear width of stairways at and below the handrail height, including treads and landings, shall be not less than 31 inches (787 mm) where a handrail is installed on one side PHOTO 3 and 27 inches (698 mm) where handrails are installed on both sides PHOTO 4.
Exception: The width of spiral stairways shall be in accordance with Section R311.7.10.1 See PHOTO 52