Stair nosing refers to the projecting edge of a stair tread that extends beyond the riser below. It's a small detail with a big impact on both the safety and aesthetics of a staircase.
Building codes have specific regulations regarding stair nosing, primarily focused on its projection (overhang). Understanding these codes and the pros and cons of nosing will help you design and build compliant and visually appealing stairs.
Maximum Nosing Projection
Most building codes limit the nosing projection to a maximum of 1 1/4 inches (32 mm). This limitation is in place for several reasons:
Trip Hazard: Excessive overhang can create a tripping hazard, especially for those with limited mobility or visual impairments.
Foot Clearance: A large projection can reduce the effective tread depth, making it difficult to place a foot fully on the step.
Code Compliance: Exceeding the maximum allowed projection can lead to building code violations.
Minimum Nosing Projection
While there's a maximum limit, some codes also specify a minimum nosing projection, typically around 3/4 inch (19 mm). This minimum ensures:
Improved Visibility: The nosing creates a visual cue that helps define the edge of the step, improving safety.
Better Footing: It provides a slightly larger tread surface, offering more secure footing.
Understanding building code requirements for stair nosing is crucial for ensuring safety and compliance. By carefully considering the maximum and minimum projection limits and weighing the advantages and disadvantages of using nosing, you can create functional and aesthetically pleasing staircases that meet both design goals and safety standards.
