What is the minimum tread depth for winder treads when the tread depth is less than 11 inches in Group R-2?

In the context of Group R-2 buildings, which typically include multi-family residential structures such as apartments, the minimum tread depth for winder treads is established to ensure safety and accessibility. Winder treads are those that are narrower on one side and are used to create a circular or elliptical stair section.

The correct answer indicates that the minimum tread depth for winder treads should be between 3/4 inch and 1-1/4 inches when the overall tread depth is less than 11 inches. This range is specifically designed to provide adequate space for foot placement, promoting safety during use. A minimum depth in this range helps to reduce the risk of slips and falls, ensuring that individuals can traverse the stairs safely without their foot being at too great a risk of misstep.

Options outside this range either do not comply with the safety guidelines or provide an inadequate tread depth that could compromise safety and functionality in the stair design. Therefore, the specified range of tread depth for winder treads in Group R-2 provides the necessary balance between functionality and safety.