Nosing refers to the overhang in your stair treads, and if you don’t have one on your stairs, OSHA Standard Number 1910.25(f)(5) requires that you provide at least 7 inches worth of leading ‘edging’ in each step. In commercial or industrial settings, stair nosings are typically fitted with a non-slip surface to increase traction making it a safety measure in the list of stair parts.

Stair NosingStair edgings/stair nosings are installed to minimize slipping and falling for stair safety reasons, leading to injuries when climbing stairs since nosings offer better grip. 2015 IBC Code Chapter 10 also requires nosings to overhang a minimum of 3/4 of an inch (19.1 mm) and a maximum of 1 1/4 inches (32 mm).