1. Stairs

2. Stairs Design

3. Why Stairs 1) Important consideration in a home
2) Accommodate flow traffic
3) Key to circulation—should be close to axis of plan

4. Stair Groupings
Groupings by Material
1) Wood
2) Steel
3) Concrete

5. Stair Terminology
KICKER

6. Stair Term Definitions
Run (total run)--horizontal distance from end to end of the stairs
Rise (total rise)--vertical distance from finished floor to finished floor
Unit run--the design size of one horizontal step
Unit rise--the design size of the vertical distance between each step

7. Stair Term Definitions
Kicker
Tread--complete horizontal size of the step, that is, the size of one unit run plus the nosing
Riser--the back portion between each tread, it is equal to the unit rise
Stringer, carriage, or stair jack--the saw tooth shape support for tread and riser
Kick block or kicker--used to keep the bottom of the stringer from sliding on the floor when a downward load is applied

8. Stair Term Definitions
Headroom--vertical distance measured from the tread nosing to the structure (wall or floor) above the stairs. Code required: 6’-8”min

9. Stair Term Definitions
Handrail--the support on the sides of the stair that you grab with your hand to aid walking up and down the stairs. Code required: 34”
Guardrail--the railing placed around an stair opening or balcony. Code required: 36”

10. Stair Term Definitions
BALUSTER
Elevation of stairs
With newel post,
Balusters, and
handrail
Newel post--the vertical post used to support the handrail at its end, also the post intersecting the handrail and guardrail
Baluster--smaller vertical supports of the handrail or guardrail. Code spacing requirement: 4”-O.C. max 6” where a triangle is formed by the tread and riser.

11. Stair Terminology
Nosing
projection of tread beyond riser
3/8” or less

12. Stair Terminology Stringer Types Plain or Made On-Site Stringer
Closed/Housed or Mill Made Stringer

13. Plain or On-Site Stringer
Notched out 2x12 to support the treads and risers

14. Closed/Housed or Mill-made Stringer
Stringer where ends of risers and treads are not exposed, usually routed so the treads and risers will fit into it

15. Types of Stairs Basic types straight run right angle or “L” double “L”
reverse or “U”
winder
spiral

16. Type of Stairs--Straight Run
Straight in design and does not change direction
Typical minimum width 3’-0”, sometimes where space can be justified 3’-6” or more

17. Type of Stairs--Right Angle or “L”
A 90 degree directional change occurs
usually occurs near the center
Platform at direction change
intermediate landing between floors

18. Type of Stairs--Double “L”
Same as L but with multiple platforms

19. Type of Stairs--Reverse or “U”
A 180 degree directional turn occurs, usually near center
Platform at direction change

20. Type of Stairs--Winder
Steps continue in pie shape fashion at landing area
Not desirable because steps are wedge shaped
The arc at the winders is 12” and the tread design not less than 10”
Handrail located where the tread is narrower
EQUAL

21. Type of Stairs--Spiral
Additional stair--not used as the main stairs
Used for unique design requirements
tight space
aesthetics

22. Framing Stairs Note double header double trimmer stringers
joist hangers

23. Design Considerations
Stairs should be comfortable to climb
degree angle is optimum

24. Design Considerations
Codes influence Sizes of Risers and Treads
Maximum angle
7 3/4” riser with 10” tread
Recommended (Common) Size Ranges
riser = 7 to 7 1/2”
tread = 10” to 10 1/2”

25. Design Rules When: Unit rise = R Unit run = T R+ T = 17” to 18”
R (x) T = 70 to 75

26. Design Rule Example If unit run is unknown
unit rise = 7” (low limit of recommended)
(high) R + T = 18 (therefore) 7 + T = 18 (then) T = 11
(low) 2R + T = 24 (therefore) 2*7 + T = 24(then) T = 10
(high) 2R + T = 25 (therefore) 2*7 + T = 25(then) T = 11
(low) R (x) T = 70 (therefore) 7 * T = 70(then) T = 10
(high) R (x) T = 75 (therefore) 7 * T = 75(then) T = 10.7

27. Design Rule Example
If unit run is unknown unit rise = 7.5” (high limit or recommended) (low) R + T = 17 (therefore) T = 17 (then) T = 9.5
(high) R + T = 18 (therefore) T = 18 (then) T = 10.5
(low) 2R + T = 24 (therefore) 2*7.5 + T = 24(then) T = 9
(high) 2R + T = 25 (therefore) 2*7.5 + T = 25(then) T = 10
(low) R (x) T = 70 (therefore) 7.5* T = 70(then) T = 9.33
(high) R (x) T = 75 (therefore) 7.5* T = 75(then) T = 10

28. Stair Calculations
Necessary to determine exact riser height and total run
1. Determine vertical distance between finished floors
2. Divide vertical distance by approximate desired riser height to set approximate number of risers
3. Round to number of whole risers
4. Divide vertical distance by number of risers to get actual riser height
5. Number of unit runs = number or unit rise minus 1
6. Total run: use design rule to determine unit run size then multiply by the number of unit runs

29. Stair Calculations Example
Given: vertical distance = 102”(Total rise)
1--Approx # unit rise = 102 / 7.5 = 13.6
2--Round 13.6 to 14
3--Unit rise height = 102 / 14 = 7.286”
4--14 unit rise (-) 1 = 13 unit runs
5--Design rule: R + T =
(therefore) T = (then) T = 10”
6--Total run = 10 * 13 = 130” = 10’-10”
Solution: ” and ”

30. Stairs Layout Procedures
1) Calculate the how many and size of Risers and Treads
2) Create box showing total rise and total run
Total Rise
Total Run

31. Stairs Layout Procedures
Divide the total rise into number of Risers (actual value of Riser)
Example:
R=14, T=13
Line at any
angle divided
Into equal
Parts, points
Transferred by
Parallel lines

32. Stairs Layout Procedures
Another approach to get equal risers
14 equal risers

33. Stairs Layout Procedures
Divide the total run into number of Treads (actual value of calculated Treads)
Line at any
angle divided
Into equal
Parts, points
Transferred by
Parallel lines

34. Stairs Layout Procedures
Another approach to get equal treads
13 Equal Treads

35. Stairs Layout Procedures
Draw grid using riser and tread divisions determined previously

36. Stairs Layout Procedures
Starting point: Head or Foot of Stairs
Follow grid and mark the design of stairs
Stair Design

37. Stairs Layout Procedures
Add actual tread boards and riser boards
Add stringer board
Tread Thickness
Stringer Size
Material Sizes
Riser Thickness
Nosing Value

38. Stairs Section Complete (Your drawing should look like handout)
Find the headroom location for structure
Locate headers to determine stairwell dimension
Add notes and dimensions
Place title and scale below drawing

39. Class Lab Work on Stair Detail/Section Assignment