Exterior Stair Tread Width Requirements: Minimum & Maximum

- Steps on a straight run must have a minimum width of 36 inches.

- This means that the tread can be no smaller than 36 inches wide.

- The maximum width of the tread is 48 inches.

- However, if the rise of the steps is greater than 7 ½ inches, the tread must be reduced by 1 ½ inches.

- For example, if the rise of the steps is 8 inches, the minimum tread width must be 34 ½ inches.

- If the rise of the steps is 9 inches, the minimum tread width must be 33 inches, and so on.

- The recommended tread width is between 11 and 14 inches.

- This allows for a comfortable step without the user feeling cramped or like they have to stretch to reach the next step.

- These requirements ensure that exterior stairs are safe and accessible for all users.