Stair Stringer Layout
Calculate exact riser height and tread depth to meet IBC requirements (max 7-inch rise, min 11-inch tread for commercial; max 7.75-inch rise, min 10-inch tread for residential).
Measure finished floor to finished floor.
Number of Risers
Exact Riser Height
Number of Treads
Total Run (11" treads)
The 3/8 Inch Rule
IBC 1011.5.4 requires that there is no more than a 3/8-inch variance between the tallest and shortest riser in a single flight. You must account for the thickness of finished flooring when cutting your bottom and top riser, often called "dropping the stringer".