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Here's the NC code ammendments for residential stairways:
R3184.108.40.206 Riser height. The maximum riser height shall be 8-1/4 inches (210 mm). The riser shall be
measured vertically between leading edges of the adjacent treads. The greatest riser height within any
flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). The top and bottom riser
of interior stairs shall not exceed the smallest riser within that stair run by more than ¾ inch (19 mm).
The height of the top and bottom riser of the interior stairs shall be measured from the permanent
finished surface (carpet excluded). Where the bottom riser of an exterior stair adjoins an exterior walk,
porch, driveway, patio, garage floor, or finish grade, the height of the riser may be less than the height
of the adjacent risers.
R3220.127.116.11 Tread depth. The minimum tread depth shall be 9 inches (229 mm). The tread depth shall
be measured horizontally between the vertical planes of the foremost projection of adjacent treads and
at a right angle to the tread's leading edge. The greatest tread depth within any flight of stairs shall not
exceed the smallest by more than 3/8 inch (9.5 mm). Winder treads shall have a minimum tread depth
of 9 inches (229 mm) measured as above at a point 12 inches (305) mm from the side where the treads
are narrower. Winder treads shall have a minimum tread depth of 4 inches (102 mm) at any point.
Within any flight of stairs, the greatest winder tread depth at the 12 inch (305 mm) walk line shall not
exceed the smallest by more than 3/8 inch (9.5 mm).
R311.5.5 Stairway walking surface.
The walking surface of treads and landings of stairways shall be sloped no steeper than one inch vertical in
48 inches horizontal (2-percent slope).
Handrails shall be provided on at least one side of each continuous run of treads or flight with four or more
Handrail height, measured vertically from the sloped plane adjoining the tread nosing, or finish surface
of ramp slope, shall be not less than 30 inches (762 mm) and not more than 38 inches (965 mm).
R318.104.22.168 Continuity. Handrails for stairways shall be continuous for the full length of the flight, from
a point directly above the top riser of the flight to a point directly above lowest riser of the flight. Handrail
ends shall be returned or shall terminate in newel posts or safety terminals. Handrails adjacent to a wall
shall have a space of not less than 1 1/2 inch (38 mm) between the wall and the handrails.
1. Handrails shall be permitted to be interrupted by a newel post.
2. The use of a volute, turnout, starting easing or starting newel shall be allowed over the lowest
3. Two or more separate rails shall be considered continuous if the termination of the rails
occurs within 6 inches (152 mm) of each other. If transitioning between a wall-mounted
handrail and a guardrail/handrail, the wall-mounted rail must return into the wall.
R322.214.171.124 Height. Handrail height, measured above the finished surface of the ramp slope, shall be
not less than 30 inches (762 mm) and not more than 38 inches (965 mm).
These adoptions give a very generous deviation from the International Residential Code:
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