IRC stair requirements are among the most commonly cited violations in residential inspections. Width: minimum 36 inches clear above handrail, 31.5 inches at and below handrail height. Risers: maximum 7-3/4 inches, minimum 4 inches. Treads: minimum 10 inches depth. Nosing: 3/4 to 1-1/4 inches when tread depth is less than 11 inches. Uniformity: maximum 3/8-inch variation in riser height or tread depth in any flight. Headroom: minimum 6 feet 8 inches measured vertically from sloped plane of nosings. Handrail: required on at least one side, 34-38 inches measured from nosing. Graspable profile: 1-1/4 to 2-inch circular cross-section, or non-circular with perimeter 4 to 6-1/4 inches. Landing: at top and bottom, minimum 36 inches measured in direction of travel. Winders: allowed if tread at 12-inch walk line is minimum 10 inches, narrowest point minimum 6 inches. Spiral stairs: minimum 26-inch width, 7.5-inch tread at 12 inches from narrow edge. These dimensions must be verified at framing inspection.