1. STAIR SAMPLE CALCULATION
Presentation 38:
STAIR SAMPLE CALCULATION

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

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

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

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

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

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

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

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