Stair Building Codes For Shaping Tread or Step Nosing - Examples For Construction Education
Building codes are essential for ensuring safety in construction, and stairways are no exception.
What is Stair Tread Nosing?
Stair nosing is the projecting edge of a stair tread that extends beyond the riser. It serves several purposes:
Enhanced Safety: Provides a larger stepping surface, reducing the risk of trips and falls.
Improved Visibility: Helps define the edge of the step, especially in low-light conditions.
Added Comfort: Offers a more comfortable place to rest your foot while ascending or descending.
Code Book Reference Number - R311.7.5.3: The Specifics
This building code outlines the requirements for nosing on stair treads, landings, and floors:
Radius of Curvature: If the nosing has a curved edge, the radius of the curve cannot exceed 9/16 inch (14 mm). This ensures the curve isn't too pronounced, which could create a tripping hazard.
Bevel: If the nosing has a beveled edge, the bevel can't be more than 1/2 inch (12.7 mm). This limits the slope of the bevel for safety.
Projection: The nosing must project between 3/4 inch (19 mm) and 1 1/4 inches (32 mm). This ensures the nosing provides enough of an extended stepping surface.
Uniformity: The greatest nosing projection within a stairway cannot exceed the smallest by more than 3/8 inch (9.5 mm). This maintains consistency and prevents unexpected changes in tread depth.
