Building Codes for Stair Tread Nosing in Staircase Specifications

After reviewing a staircase specification checklist, it is important to research the code requirements for your specific application. This checklist provides an outline and some example codes for risers, stringer slope, stair treads, stair tread nosing, and landings.

Do your stair tread nosing meet these codes?

  • Stair Risers
    • Step riser specifications riser height (<= 7.75″)
    • Step riser height uniformity (<= 3/8″ variation)
      • 1009.3.1 Dimensional uniformity. Stair treads and risers shall be of uniform size and shape. The tolerance between the largest and smallest riser or between the largest and smallest tread shall not exceed 0.375 inch (9.5 mm) in any flight of stairs. – NYS 2007
    • Step riser slope (out of vertical) (<= 30 deg measured from horizontal surface of the tread)
    • Open risers are permitted provided the opening will not pass a 4″ sphere (child safety)
  • Stair Stringer Slopes – different types in various building entry/exit points
    • Accessible stairs: slope 30 to 32.5 deg.
    • Access ramps: slope 0 to 20 deg, prefer 7 to 15 degrees of slope
    • Egress stairs and accessible egress stairs: (primary exit from a building), slope 30-32.5 deg.
    • Fire escape stairs (for emergencies), slope 30-50 deg.
    • Limited access stairs (fixed industrial stairs), slope 30 to 50 deg. (utility stairs, stairs to access mechanical systems, etc)
  • Stair Treads
    • Step tread depth (=> 10″)
    • Step tread depth uniformity (<= 3/8″ variation)
    • Stair tread depth for winder stairs (>= 6″ at smallest point)
    • Stair tread uniformity for winder stairs at the 12″ walk-line (<= 3/8″ variation)
    • Stair tread slope (out of level on walking surface) – (slope or “rise” must be <= 1 in 48)
    • A walking-surface that provides a coefficient of friction of 1.02 dry and 0.98 wet will comply with ADA, OSHA, and most local building codes and insurance requirements.
    • Stair Code Example – Source BOCA 2001 stair construction code details:
      • Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum.
      • Stair tread depths shall be 11 inches (279 mm) minimum. The riser height shall be measured vertically between the leading edges of adjacent treads. The stair tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at right angle to the tread’s leading edge.
  • Stair Tread Nosing
    • Stair tread nosing projection past vertical riser below (3/4″ to 1 1/2″) required on stairs with solid risers
    • Tread nose projection uniformity (<= 3/8″ variation)
    • Stair tread nosing curve radius (=< 9/16″)
    • Tread Nose not required if tread depth is => 11″
    • Tread Nose not required on open stair treads (open riser)
    • 2008 New York State Stair Code R311.5.3.3: Stair Tread [nose]
      • The greatest stair tread nosing projection shall not exceed the smallest nosing projection by more than 3/8 inch (9.5 mm) between two stories, including the nosing at the level of floors and landings.
      • A nosing is not required where the tread depth is a minimum of 11 inches (279 mm).
  • Stair Landings
    • There must be a floor or landing at the top and bottom of each stairway and on each side of each exterior door.
    • Exception: exterior doors, except the required main exit door, where there are two or fewer risers, a landing is not required.
    • Stair landing minimum size in direction of travel (<= 36″)

Building Code Guides to Stairway, Railings & Landing Construction or Inspection:

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