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Home / Code Guides / Notching & Boring

Notching and Drilling Code — Joists, Studs & Top Plates

Every trade drills the frame, and the IRC gives each member a budget: how deep a notch, how big a hole, and where. Blow the budget and the fix is a strap, a header, or an engineer.

RequirementModel Code StandardSection
Joist notchesNotches no deeper than one-sixth the joist depth, no longer than one-third the depth, and never in the middle third of the span; end notches up to one-fourth the depthIRC R502.8.1
Joist holesHoles no larger than one-third the joist depth, kept at least 2 in. from the top and bottom edges and from any other hole or notchIRC R502.8.1
Bearing-wall studsNotches up to 25% of stud width; bored holes up to 40% — 60% only when the stud is doubled and no more than two successive studs are boredIRC R602.6
Non-bearing studsNotches up to 40% and holes up to 60% of the stud widthIRC R602.6
Hole edge distanceBored holes must keep at least 5/8 in. of wood to the stud edge and must not land in the same section as a notchIRC R602.6
Top plate repairWhere a plumbing or duct chase cuts more than 50% of a top plate, a 16-gauge, 1.5 in. metal strap with prescribed nailing must bridge the cutIRC R602.6.1

Worth knowing

  • Engineered lumber has no notch budget at all outside the manufacturer’s literature — never field-notch an I-joist flange (R502.8.2).
  • The classic violation is the 3.5 in. hole saw for a DWV stack through a 2×4 bearing wall: a 3.5 in. hole in a 3.5 in. stud is 100%, not 40%.
  • Kitchen and bath remodels concentrate all three rules in one wall — plan chases before demo, not after rough-in.
  • Straps and shoes from framing hardware makers are code-friendly fixes, but they repair plates, not joists — an over-notched joist gets sistered or engineered.
Sections cite the 2021 International Residential Code and 2023 National Electrical Code as model standards. This is BuildSpec’s own summary — not ICC or NFPA text; read the authoritative language at codes.iccsafe.org. Your state may be on a different edition with amendments — check your jurisdiction page or get an Address Report.
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