For stairways that require handrails, which type is excluded from having handrails on both sides?

Spiral staircases are unique in their design, typically featuring a central column with treads that radiate outwards, which limits space for traditional handrails. Building codes often allow for the omission of handrails on one side of spiral staircases since the compact design inherently restricts movement and the type of traffic they accommodate. Additionally, the central pole itself may sometimes serve as a handrail, or the design might be inherently safe enough that the omission does not significantly increase risk.

Open staircases and wide stairways typically maintain a conventional design necessary for usability and safety, necessitating handrails on both sides to accommodate users of varying needs. Residential stairs, while they can have design flexibility, still generally follow building code requirements for handrail installation to ensure safety across all home inhabitants and visitors. Thus, spiral staircases stand out as the exception that can often forgo handrails on one side.