How high can a stair flight rise before a landing?
Under the 2018 IRC (§R311.7.3), a single stair flight may rise no more than 12 feet 7 inches (151 inches) of vertical height between floor levels or landings. Climb higher than that and you must break the run with an intermediate landing, at least as deep as the stairway is wide.
Source: 2018 IRC §R311.7.3 · Verify against your AHJ and the adopted code edition.
A stair can only climb so far in one continuous run. The IRC caps the vertical rise of a single flight at 12 feet 7 inches (151 inches) between floors or landings (§R311.7.3). Go higher and you must insert an intermediate landing.
A couple of related rules:
- The landing has to be at least as deep as the stairway is wide (so a 36-inch-wide stair needs a landing at least 36 inches deep in the direction of travel).
- Landings are also where a stair can change direction — a switchback needs the landing anyway.
For a typical 7½-inch riser, 151 inches works out to about 20 risers before a landing is required — most single flights in a house never reach it, but a tall foyer or a walk-out basement can.
Work it out: the stair calculator reports the total rise and flags when a flight exceeds the 151-inch limit, so you know to add a landing.
Sources
- ICC — International Codes (IRC) — 2018 IRC §R311.7.3