Cabinet and Finish Carpentry (C-6) · Lesson 2 of 6

Stair Layout: Rise, Run, and Baluster Spacing

"Stair Layout: Rise, Run, and Baluster Spacing" is lesson 2 of 6 in the Cabinet and Finish Carpentry (C-6) Learning Hub. It opens with "Start With the Total Rise" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. Start With the Total Rise
  2. Count the Risers, Then Size Them
  3. Find the Treads and the Run
  4. Handrails and Guards
  5. Spacing Balusters to Pass the Sphere Test

The worked example in the course applies this lesson to a realistic job in 6 steps, from "Check total rise" through "Sloped stair side".

What you'll be able to do

  • Explain the main idea of "Stair Layout: Rise, Run, and Baluster Spacing" in plain language you can use on the exam.
  • Apply this step with confidence: "Find the Treads and the Run".
  • Apply this step with confidence: "Handrails and Guards".
  • Apply this step with confidence: "Spacing Balusters to Pass the Sphere Test".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Stair Layout: Rise, Run, and Balusters TOTAL RISE 108 in RISER 7-23/32 in x 14 risers TREAD 10-1/2 in RUN 13 x 10-1/2 = 136-1/2 in STAIR LAYOUT (CRC R318.7.5) 108 / 7.75 max = 13.94 Round UP: 14 risers Riser = 108 / 14 = 7.714 in (7-23/32) Treads = 14 - 1 = 13 (top is the floor) Run = 13 x 10.5 = 136.5 in Limits: riser ≤ 7-3/4, tread ≥ 10 in, variation within a flight ≤ 3/8 in LEVEL GUARD (4 in sphere) 60 in opening, 1-1/4 in square balusters (60 - 1.25n)/(n + 1) < 4 gives n ≥ 11 n = 11: gap 3.85 in | n = 10: 4.32 in fails 14 risers at 7-23/32 in and 13 treads at 10-1/2 in: PASSES Guard: 11 balusters, every gap under the 4 in sphere Source: 2025 California Residential Code R318.7 (stairs) and R321.1.3 (guards).CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: Start With the Total Rise

Total rise is the vertical distance from the finished floor at the bottom to the finished floor at the top, measured after flooring thickness is accounted for on both levels. The 2025 California Residential Code (CRC) R318.7.3 says a flight of stairs shall not have a vertical rise greater than 12 feet 7 inches (151 inches) between floor levels or landings. In the 2025 CRC stairways are in R318.7, not the older R311.7 numbering. R318.7.5 also says stair dimensions exclude carpets, rugs and runners.

Step 2: Count the Risers, Then Size Them

CRC R318.7.5.1 limits riser height to 7-3/4 inches maximum, measured vertically between the leading edges of adjacent treads. Divide the total rise by 7-3/4 and always round UP to a whole number of risers, then divide the total rise by that whole number to get the actual riser height. The greatest riser in a flight may not exceed the smallest by more than 3/8 inch. Open risers more than 30 inches above the floor or grade below may not pass a 4-inch sphere.

The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

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