The 2021 IRC, R311.7.3, states that a flight of stairs shall not have a vertical rise greater than 12 feet 7 inches (3835 mm or 151 inches) between floor levels or landings. The code also states that there are exceptions to this vertical height limit. They are: (a) Stairways not within or serving a building, porch, or deck; (b) Stairways leading to non-habitable attics; and (c) Stairways leading to crawl spaces. The 2021 IBC, Section 1011.8, states that a flight of stairs should not have a vertical rise greater than 12 feet (3658 mm or 144 inches). The vertical height is measured from one landing walking surface to another.