Obtaining an accurate and appropriate stair measurement is crucial to determine code compliance. The 2012 IBC code commentary provides great insight and guidance as to how to measure stairs and provide accurate information to those looking to see if their stairs are in compliance.

Riser Height = Vertical dimension from the tread surface to next adjacent tread surface. Typically limited to 7 inches maximum and 4 inches minimum.

Tread Depth = Horizontal distance from the leading edge (nosing) of one tread to the leading edge (nosing) of the next adjacent tread or landing. Typically limited to no less than 11 inches. The tread depth is intended to accommodate the largest shoe size found in 95 percent of the adult population.

See the images below for a visual understanding of the correct way to measure stairs.

Proper measurement of stairs from the 2012 Commentary to the IBC.

Proper measurement of stairs from the 2012 Commentary to the IBC.