Glossary: Tread Depth
**Tread Depth** is the horizontal depth of a stair step run, measured from the riser face to the nosing edge, required to be a minimum of 10 inches under standard building codes.
Stair step Tread Codes
Treads provide footing surfaces. Under building codes, nosings (overhangs of 3/4 to 1.25 inches) are required if tread depths are under 11 inches to ensure safe footing support.