Stair geometry
Minimum tread depth, maximum riser height, headroom, and handrail dimensions for residential stairs in North Carolina.
- Code book
- 2018 NC Residential Code (based on 2015 IRC)
- Last reviewed
- 2026-04-14
RisersR311.7.5.1#
Residential stair risers have a maximum height of 8.25 inches. The greatest riser height in a single flight cannot exceed the smallest by more than 0.375 inches.
TreadsR311.7.5.2#
Minimum tread depth is 9 inches measured from nose to nose. The greatest tread depth in a flight cannot exceed the smallest by more than 0.375 inches.
HeadroomR311.7.2#
Minimum headroom is 6 feet 8 inches, measured vertically from the sloped line connecting the tread nosings to the ceiling or the bottom of any structure above.
HandrailsR311.7.8#
Handrails are required on at least one side of any stair with four or more risers. Handrail height is measured vertically from the sloped plane of the tread nosing and must be between 34 and 38 inches.
Handrails must be graspable. Type I handrails (circular) have an outside diameter between 1.25 and 2 inches. Type II handrails (non-circular) have a perimeter between 4 and 6.25 inches with a cross-section no greater than 2.25 inches.
Common inspection flags#
The most common stair failures on a residential framing inspection:
- Riser height variation greater than 0.375 inches in the same flight
- Missing or out-of-range handrail on a flight with four or more risers
- Headroom under a landing soffit measuring under 80 inches
- Nosing projection under 0.75 inches on a tread with a beveled edge