When is a handrail required on stairs?
Under the IRC, stairways with 4 or more risers require at least one handrail (§R311.7.8.1). The top of the gripping surface must sit 34 to 38 inches above the stair nosings, and the handrail must run continuously and be graspable along the flight. This is separate from any guard required at an open side.
Source: 2018 IRC §R311.7.8 · Verify against your AHJ and the adopted code edition.
The trigger is the riser count: a residential stairway with 4 or more risers needs at least one handrail (IRC §R311.7.8.1). Three or fewer risers don’t require one.
Key dimensions:
- Height: 34–38 inches, measured vertically from the nosings of the treads to the top of the gripping surface.
- Continuous and graspable. The handrail should run the full length of the flight, and its cross-section has to be easy to grip (round rails roughly 1¼–2 inches in diameter, with limits on non-circular shapes).
A handrail is not a guard. A handrail is the graspable rail you hold at 34–38 inches; a guard is the barrier at an open side more than 30 inches above the floor, at least 36 inches high in a home. On an open stair you often need both — see how tall a guardrail needs to be.
Work it out: the stair calculator flags when a flight reaches 4 risers so you know a handrail is required, alongside the riser, tread, and pitch checks.
Sources
- ICC — International Codes (IRC) — 2018 IRC §R311.7.8