Framing and Rough Carpentry (C-5) · Lesson 1 of 5

Notching and Boring Limits for Joists, Rafters, and Studs

"Notching and Boring Limits for Joists, Rafters, and Studs" is lesson 1 of 5 in the Framing and Rough Carpentry (C-5) Learning Hub. It opens with "Why Cutting Framing Is Regulated" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. Why Cutting Framing Is Regulated
  2. Joists: Notch Limits (2025 CRC R502.8.1)
  3. Joists: Bored Hole Limits (2025 CRC R502.8.1)
  4. Studs and Top Plates (2025 CRC R602.6 and R602.6.1)
  5. Engineered Lumber Is Different, and How to Check a Request

The worked example in the course applies this lesson to a realistic job in 6 steps, from "Find actual depths" through "Conclusion".

What you'll be able to do

  • Explain the main idea of "Notching and Boring Limits for Joists, Rafters, and Studs" in plain language you can use on the exam.
  • Apply this step with confidence: "Joists: Bored Hole Limits (2025 CRC R502.8.1)".
  • Apply this step with confidence: "Studs and Top Plates (2025 CRC R602.6 and R602.6.1)".
  • Apply this step with confidence: "Engineered Lumber Is Different, and How to Check a Request".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Drilling and Notching Limits: Joist and Stud2x10 JOIST SIDE VIEW (9-1/4 IN. DEEP) top 2 in.: no holes bottom 2 in.: no holes 3.08 3.50 Max bore 3.08 in. Pipe as measured OD 3.50 in. d = 9-1/4 in. JOIST 2x10, d = 9-1/4 IN. (CRC R502.8.1) Bored hole, d / 3 = 3.08 in. Top/bottom notch, d / 6 = 1.54 in. End notch, d / 4 = 2.31 in. BEARING 2x4 STUD, 3-1/2 IN. (CRC R602.6) Max notch, 25 percent = 0.875 in. Max bore, 40 percent = 1.40 in. Bore up to 60 percent = 2.10 in. (over 40 percent: stud must be doubled) Hole edge at least 5/8 in. from stud edge JOIST: 3.50 in. pipe > 3.08 in. max bore = HOLE FAILS 2.375 in. pipe ≤ 3.08 in. = OK, centered in the joist STUD: 1.50 in. hole = 43 percent of 3.5 in. (over 40 percent) Bearing stud must be doubled to take the 1.50 in. hole Source: 2025 CRC R502.8.1 (joists) and R602.6 (studs); no notches in the middle third of a joist spanCC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: Why Cutting Framing Is Regulated

A joist or stud carries its load through its full depth. Wood in the top and bottom of a joist works hardest in bending, and wood at the edges of a stud keeps it from buckling, so a careless hole or notch can turn a sound member into a weak one. Plumbers, electricians, and HVAC installers cut and drill your framing, and the framing contractor is often the person asked, "Can I go through this?" The answer comes from fixed fractions and percentages of the member depth in the 2025 California Residential Code (CRC).

Step 2: Joists: Notch Limits (2025 CRC R502.8.1)

In solid sawn floor joists, rafters and beams, a notch may not be deeper than 1/6 of the depth of the member, may not be longer than 1/3 of the depth, and may not be located in the middle third of the span. Notches at the ends of the member may not exceed 1/4 of the depth. On members 4 in. or more in nominal thickness, the tension (bottom) side may not be notched except at the ends. Rafters follow the same rule: R802.7.1 sends cuts, notches and holes in solid lumber rafters to R502.8.1, so a bird's mouth heel cut at the bearing end may not exceed 1/4 of the rafter depth. Notches on a cantilevered portion of a rafter are the one exception, governed by R802.7.1.1 (remaining rafter at least 3-1/2 in., cantilever not over 24 in.).

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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