What are the maximum rise and run specifications for public stair treads?

The maximum rise for public stair treads is set at 180mm. This value is established to ensure that stairs remain safe and accessible for all users, including individuals with varying levels of mobility, such as those who may have difficulty navigating steeper rises. A rise of 180mm strikes a balance between safety and maintainability, reducing the risk of trips and falls.

While the run (the depth of the tread) is not limited by this specification, it is essential for the run to provide adequate space for the foot to rest securely. Wider runs allow for a more comfortable ascending and descending experience. However, what is notable is that having a higher rise while maintaining an unlimited run could lead to discomfort or dangers in navigating stairs, which the building codes aim to mitigate. In contrast, the options that present rises higher than 180mm fail to meet accessibility standards, thus making the specified choice the most suitable.