CALCULATING STAIRS, STAIR RUNS, RISERS AND TERMINOLOGY

1. Maximum Riser Height is 7-3/4".
2. Minimum Tread Depth is 11".
3. Riser Heights and tread depths should not differ from each other by more than 3/8".
4. Minimum Head Room is 6'8"
5. Landings must always be at least as wide as the tread depth

(Based on 2006 IRC)

1. Determine "Total Rise" by measuring the distance from the top landing area to the floor, sidewalk or deck surface below. (Consider any flooring to be installed later)
2. Divide Total Rise by the desired riser height.
3. If the result of step 2 is not a whole number, round up or down to the whole number. And again, divide the total rise by the new :whole number" to determine the riser height. (Remember to comply with codes)

Example:

1. Total rise is 27" and you would like to have a riser height of around 6". Total rise is 27"
2. 27" divided by 6" = 4.5
3. Since you cant have 4.5 risers, choose 4 or 5.
   27 divided by 4 = 6.75
   27 divided by 5 = 5.4" (6.75" is more desirable than 5.4")

1. After calculating the number of risers you will have, subtract 1 (this will tell you how many treads you will have)
2. Multiply Risers (from step 1) by the tread depth. This is your total run.

Example: Total run for a set of stairs that will have 8 risers with a tread depth of 10".

1. 8 - 1 = 7
2. 7 x 10 = 70

(Total Run)