When should a third stairway stringer be used?

A third stairway stringer is typically required for wider staircases to ensure proper support and stability. The correct answer indicates that a third stringer should be used when the stair width exceeds 30 inches. This guideline is based on building codes and standards that emphasize safety and structural integrity.

When stair widths are significant, additional support becomes crucial to prevent sagging and potential hazards for users. A structure with only two stringers may not adequately support the weight distributed across a wider surface, especially when fully loaded with people or objects. Thus, a third stringer helps maintain a secure and safe stairway by providing additional support at the center, balancing the load, and preventing movement or wobbling.

While other choices indicate different width thresholds for adding a third stringer, the established standard for many building codes is to implement a third stringer starting at 30 inches. Adhering to this guideline helps contractors ensure that their stairways comply with safety regulations and offers reliable performance over time.