What is the smallest radius of winder treads in curved stairways based on the minimum width or required capacity?

The smallest radius of winder treads in curved stairways is determined by both safety and accessibility requirements. The answer indicates that the radius should be at least twice the width of the winder treads. This requirement ensures that the stairs are not only structurally sound but also safe for users.

A radius that is twice the width of the treads provides adequate space for individuals to navigate the stairs comfortably without feeling cramped or risking a fall. This consideration is crucial in public and commercial buildings where stairway design must adhere to safety codes and regulations.

When the radius is set at twice the width, it allows for more effective weight distribution and stability in the stair design. It accommodates the natural movement of individuals as they ascend or descend, ensuring that there’s enough room to maneuver without the risk of slipping or tripping over the edges of the stairs.

Other options, such as half, three times, or four times, do not align with established guidelines for safety and usability. A radius smaller than twice the width could create hazardous conditions, while those larger than twice the width may be unnecessarily cumbersome or unfeasible for design within the space constraints typically found in commercial buildings.