What is the minimum headroom above a stairway?
Stairs need at least 6 ft 8 in of headroom (IRC R311.7.2).
The IRC requires a minimum headroom of 6 feet 8 inches (2032 mm) over the full run of the stairway, measured vertically from a line connecting the tread nosings and from the surface of any landing.
This clearance must be held for the entire width of the stairs. Because it is lower than the 7-foot ceiling required for habitable rooms, a stair tucked under a sloped ceiling or soffit can still comply as long as the full 6 ft 8 in is preserved.
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