Stairways in a means of egress have to meet strict geometry so people can move quickly and safely under pressure. IBC 1011 sets the rules: risers between 4 and 7 inches, treads at least 11 inches deep, and — critically — uniformity, since the largest riser or tread in a flight can't exceed the smallest by more than 3/8 inch. Minimum width is generally 44 inches (36 inches where the occupant load is under 50), headroom at least 80 inches, and landings required at the top, bottom, and where doors open.
Beyond geometry, stairways need compliant handrails (see the handrails guide), and interior exit stairways serving multiple stories usually require rated enclosure.
The common mistake is non-uniform risers — often introduced when a slab or landing elevation shifts during construction and the stair gets rebuilt to fit. Reviewers check the stair section for riser/tread dimensions, uniformity, width against occupant load, and headroom, because a stair that fails geometry is both a code violation and a real trip hazard.
This guide describes the model code for general understanding and is not a substitute for the adopted code and amendments enforced by your local authority having jurisdiction. Verify all figures against your jurisdiction's codes of record.