ABSTRACT
This illustration shows a 6′-0″ platform. It is easier to work this sort of problem using all inches, which would be 72″. Nine inches would be the tallest possible rise, and 72″ divided by 9 results in eight rises to get from the floor to the top of the platform. One of the 9″ rises is actually the space that occurs between the top step and the platform. As a result, this stair would have eight rises but only seven treads. You could just as well use a riser height of 8″, which would mean nine rises and eight treads. A 7″ rise would result in 10.3 risers, which of course wouldn’t work.
