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I have a garage which is a simple structure - 4 walls, garage door, and a normal door. The structure is framed as one would expect, studs 16 inches apart. I want to put some extra wood paneling as an inside wall in order to make it look nicer, however I see that on one wall, I have a long electrical conduit (EMT) running half the length of the wall that I would have to move. The conduit is attached on the outside of the studs (interior to the garage space itself).

My question is, since these studs all together bear the weight of the roof, is it okay to cut a half inch notch to run conduit? I don't have much experience with this and I just want to make sure I won't weaken the structure so that it collapses. I live in Chicago so I have strong winds.

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    It's a garage. Rather than make a lot of extra work, detach the conduit, install paneling, reattach conduit to surface. If desired, paint to roughly the color of the paneling (might be easiest to do that first.) For a fancier job, box the conduit in paneling (still on the surface of the wall.) – Ecnerwal Aug 9 '15 at 21:09
  • If you box the conduit in a sturdy enough fashion, you could put couch cushions on it and you'd have built-in seating! Bahahahah... ;-) – Craig Aug 9 '15 at 21:42
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    IMO, notching effectively reduces the entire member to the cross section of the notch. There's two ways I'd do this: surface mount it again or re-pipe it through holes drilled in the centers. You can drill a thousand holes in lumber and maintain integrity; one 4" notch in a 2x8 and you have yourself a 2x4 (an over statement, as this violates code, but I see it in the field all the time). – Mazura Aug 9 '15 at 21:49
  • @Mazura you're definitely right about notching reducing the entire effective cross section of a beam to the width of the beam minus the depth of the notch (or even worse, because wood grain is never completely straight). But a stud is supporting a columnar load, so it's a little different. Still, I totally agree that the preference should be to bore through the stud rather than notching it if that's a reasonable option. Still, code permits notching within specific constraints, which would not be the case if it was grossly unsafe. In this case, personally I'd (carefully) notch the studs. – Craig Aug 10 '15 at 0:11
  • And I would put protective nailing plates over the notches. – Craig Aug 10 '15 at 0:12
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The rule is that the studs in any exterior or load-bearing wall may be notched, but no deeper than 25% of the width of the stud, or a hole no bigger than 40% of the width of the stud may be bored in it (you could pass the conduit or cable through the stud). There's an exception that you can notch 60% of the depth if the stud is doubled and no more than two successive studs are notched that deeply. Non-load-bearing studs can be notched up to 40% of the depth of the stud.

Also, you cannot notch the side of the studs that structural sheathing/plywood is affixed to (see shear walls).

Here's the seemingly relevant International Building Code section:

R602.6 Drilling and notching - studs. Any stud in an exterior wall or bearing partition may be cut or notched to a depth not exceeding 25 percent of its width. Studs in nonbearing partitions may be notched to a depth not to exceed 40 percent of a single stud width. Any stud may be bored or drilled, provided that the diameter of the resulting hole is no greater than 40 percent of the stud width, the edge of the hole is no closer than 5/8 inch (15.9 mm) to the edge of the stud, and the hole is not located in the same section as a cut or notch. See Figures R602.6(1) and R602.6(2).

Exceptions:

  1. A stud may be bored to a diameter not exceeding 60 percent of its width, provided that such studs located in exterior walls or bearing partitions are doubled and that not more than two successive studs are bored.
  2. Approved stud shoes may be used when installed in accordance with the manufacturers recommendation. R602.6.1 Drilling and notching of top plate. When piping or ductwork is placed in or partly in an exterior wall or interior load-bearingwall, necessitating cutting, drilling or notching of the top plate by more than 50 percent of its width, a galvanized metal tie of not less than 0.054 inches thick (1.37mm) (16ga) and 11/2 inches (38mm) wide shall be fastened to each plate across and to each side of the opening with not less than eight 16d nails at each side or equivalent. See Figure R602.6.1.

Exception: When the entire side of the wall with the notch or cut is covered by wood structural panel sheathing

Is this EMT (metal conduit)? I would consider putting protective metal nail plates over the notches, as well. If it isn't metal conduit, I'm pretty sure you have to use those plates.

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  • Are all exterior walls load bearing? – Kris Aug 9 '15 at 21:05
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    @Kris that's an interesting question. If the building is a box, then all of the exterior walls would be load-bearing since they all hold the roof up equally (presuming the trusses are engineered and built so they don't exert any lateral loads). But with a more complex footprint, I suppose it's possible you might have a small section of wall here or there that is filling space, but not really holding up a substantial load? I'd probably err on the side of safety, though, and assume they're all load-bearing, barring an explicit declaration to the contrary from an engineer. – Craig Aug 9 '15 at 21:08
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    You should use protection plates no matter what it is, esp. to cover notches (I think code says you're ok if it's centered in holes -there's a set back distance, IIRC). It also 'must' be EMT in Chicago. – Mazura Aug 9 '15 at 21:39

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