Final answer:
On stairways with solid risers, a nosing should be at least 1/4 inch and not more than 1 1/2 inches. Nosing is the part of the tread that extends beyond the riser, enhancing safety and usability of stairs in compliance with building codes such as the IBC and NFPA.
Step-by-step explanation:
The question pertains to the design requirements of stairways, specifically the dimension of nosings where solid risers are present. In terms of safety and compliance, nosings on stairs play a critical role. According to the International Building Code (IBC) and the National Fire Protection Association (NFPA), a nosing on stairways with solid risers should be at least ¼ inch and not more than 1½ inches protruding over the tread below. Nosing is the part of the tread that extends beyond the riser; it improves the safety of the staircase by providing extra space for users to place their feet as they ascend or descend the stairs. This specification helps to minimize the risk of trips and falls while also taking into account the ease of use for pedestrians. It's important to consult local building codes as they may have more stringent or specific requirements.