What is the minimum inside tread depth on a curved staircase?

The minimum inside tread depth on a curved staircase is typically 6 inches. This measurement is important for safety and usability, ensuring that the steps are deep enough for a secure footing. A tread depth of 6 inches allows for comfortable foot placement as individuals ascend or descend the staircase.

In curved staircases, where the radius changes, maintaining this minimum depth helps in reducing the risk of slips and falls, making the staircase safer for users. Additionally, building codes often specify these measurements to promote safe design practices for all types of staircases, including those that are curved.

Other options, while they may seem plausible, do not meet the established safety standards for tread depth. A tread depth that is too small can compromise stability, making it difficult for a person to walk down or up comfortably, especially when navigating a curve. Thus, the standard of 6 inches is set to optimize safety and functionality in curved stair designs.