Generally, residential stairs are to be a minimum width of 36" with a maximum rise of 7 ¾” and a minimum run of 10” with no more than a 3/8” difference between the smallest and greatest. Graspable, continuous handrail the full length of the flight of stairs with four or more risers shall be between 34” & 38” in height Guards are required if the platform surface is more than 30” from grade and shall not be less than 34” in height. Vertical rails should not allow passage of a sphere 4” in diameter.
For more information:
Residential Stairs One & Two-Family Dwellings