1. 1 Presentation 38: STAIR SAMPLE CALCULATION

2. 2 Sample Stair Calculation 8′-0″ 11 ¼″ Given: –Upper Const. = 11 ¼″ –Floor to ceiling = 8′-0″ –Headroom = 80″ –Unit Run = 10 ¾″

3. 3 Sample Stair Calculation 8′-0″ 11 ¼″ Find: –Total rise –# of risers –Unit rise –Stairwell length

4. 4 Total Rise 8′-0″ 11 ¼″ Total rise = 107 ¼″ 8′-0″ + 11 ¼″ = 107 ¼″

5. 5 Number of Risers 8′-0″ 11 ¼″ # of risers = 107 ¼″ ÷ 8 = 13.406  14 or 15 risers 107 ¼″

6. 6 Unit Rise 8′-0″ 11 ¼″ Unit rise = 107 ¼″ 107 ¼″ ÷ 14 = 7.66″ 7 11 / 16 ″ 107 ¼″ ÷ 15 = 7.15″ 7 1 / 8 ″

7. 7 Unit Rise 8′-0″ 11 ¼″ 17 to 18 Rule 107 ¼″ Unit Rise 7 1 / 8 ″ 15 risers Since unit run is 10.75″ Best unit rise = 10.75 + 7.66 = 18.41 or 10.75 + 7.15 = 17.90 7.15 is the better choice since 17.90 is between 17 and 18.

8. 8 Stairwell Length 8′-0″ 11 ¼″ Stairwell length = 107 ¼″ 139 ¾″ Unit Rise 7 1 / 8 ″ 15 risers 80″ + 11 ¼″ = 91 ¼″ 91.25″ ÷ 7.15 = 12.1667  13 treads in opening 13 x 10.75 = 139.75″

9. 9 Conclusion 8′-0″ 11 ¼″ Find: 107 ¼″ 139 ¾″ Unit Rise 7 1 / 8 ″ 7 1 / 8 ″ 107 ¼″ 15 139 ¾″ 15 risers –Total rise: –# of risers: –Unit rise: –Stairwell length: