How Wide Should Stair Treads Be?

Rise and Run

• Measure the rise and the run of the staircase to calculate your stair dimensions. The rise is the change in vertical height, and the run is the horizontal distance the stairs will cover. Landings are used when the run of the staircase is longer than the width of seven or eight stairs. Turns in the staircase are used when the rise is longer than the run.

Be Consistent

• Stair riser height and stair tread width must be kept consistent over the flight of stairs. Our brains sense the stair height after the first step.This allows us to walk up stairs without looking at our feet or focusing on the task. People will trip if the riser height changes. Most building codes only allow for a small variance --- less than a quarter of an inch --- in riser height over a flight of stairs.

Outdoor and Indoor Steps

• Outdoor stairs should be more foot-friendly because rain and snow can make them slippery. Outdoor treads should be at least 12 inches. Risers should be 7 inches or less. Indoor steps can be steeper, with a narrower tread. There is less room to manage steepness with landings indoors. Most building codes have a minimum 9-inch width for residential staircases.

Public Buildings

• Large public buildings, such as museums and courthouses, are designed with wide-step treads with short risers. This is done for visual effect and to accommodate more people on the stairs. However, risers should not be less than 4 inches, since people generally cannot adjust their gait to a shorter rise.