There are certain measurements that a staircase needs to conform to in order to meet building regulations.

Tread length

The minimum tread length is typically around nine inches. It’s notable that the majority of human feet are longer than this, so in effect the whole foot does not fit on the step where the minimum length is employed.

Maximum riser height

This is literally the difference in height between one step and the next. It’s normally around 8.25 inches. When this maximum is combined with the tread length minimum, a maximum incline is established. The steepness can be greater in residential properties than commercial or industrial ones and other public buildings.

In addition to this, there are specifications about how much each step can vary from the others. Regulations might specify that steps can vary by as little as 0.25 inches. The reasoning behind this is that people get used to a certain step height when climbing stairs and irregular steps can prove dangerous, particularly when ascending or descending at night.

Generally speaking, all steps in a flight should be as close to identical as possible. With differences in floor to floor height and in the available horizontal space from one building to the next, staircases should be custom made to ensure that they meet these regulations.