Wall Stud Notching and Boring Limits (IRC R602.6)
The 'can I drill or notch this stud' field check on the actual stud width.
Example
You enter
- Actual stud width (in, 2x4 = 3.5, 2x6 = 5.5) 5.5
You get
- Max notch (bearing / exterior) 1.375 in (25%)
- Max bore, single stud in an exterior or bearing wall 2.200 in (40%)
- Max bore, any nonbearing stud or a doubled bearing stud 3.300 in (60%)
Checked against published worked examples from: City of Richmond, KY (building inspection).
Details, formula, and sources
Scopea notch may not exceed 25% of the width in a bearing or exterior wall, or 40% in a nonbearing wall; a bored hole may not exceed 60% of the width, and a stud in an exterior or bearing wall bored over 40% must be doubled (up to two successive), with the hole edge at least 5/8 in from the stud edge and not in the same cross section as a notch. A 2x6 (5.5 in) bearing stud allows a 1.375 in notch and a 2.20 in single bore; a 2x4 (3.5 in) nonbearing stud allows a 1.40 in notch. Prescriptive IRC limits; a plumbing/mechanical wall, an engineered stud, or a shear wall may be tighter, and the AHJ-adopted code governs. A field check, not a stamped detail.
Formula or tablenotch_max_bearing = 0.25 x stud_width; notch_max_nonbearing = 0.40 x stud_width; bore_single_max = 0.40 x stud_width (a single stud in an exterior wall or bearing partition); bore_doubled_max = 0.60 x stud_width (any stud; an exterior or bearing stud bored past 40% must be doubled); edge_min = 0.625 in (5/8 in).
Source and editionIRC R602.6 wall-stud notching and boring limits, by name; the percentages apply to the actual stud width. The AHJ-adopted IRC edition governs.
Free accessThe percentage limits are prescriptive IRC R602.6 values (many jurisdictions post the adopted IRC); the tile applies them to the entered actual stud width.
What governsEstimate. AHJ and licensed professional govern.
API field namesstud_width_in, notch_max_bearing_in, bore_single_max_in, bore_doubled_max_in
- Actual width percentages apply to the actual dressed width (2x4 = 3.5 in, 2x6 = 5.5 in), not the nominalIRC R602.6
- Doubled stud / edge bore up to 60% in any stud; an exterior or bearing stud bored over 40% is doubled (<=2 successive); hole edge >= 5/8 in; not in the same section as a notchIRC R602.6