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Community and Q&A

Notching Studs

michaelbluejay | Posted in Building Code Questions on

SUMMARY:  How deeply can a notch a bearing stud across its depth (not across its width)?  Code seems to speak to the latter, but not the former.

DETAILED:  My 2×6 studs are 24″ on center, leaving 22.5″ between them.  There is only one 120V AC/heat heat pump window unit on the market I can find, Frigidaire FFRH0822R1.  In its infinite wisdom, Frigidaire made the units 22-11/16 wide.  That would call for notching each stud 3/32″, maybe more if the studs aren’t laid out perfectly.  IRC 602.6 seems to talk about notching against the width of a stud, but not against the depth.  How deeply can I notch against the depth?  I’m really hoping to not have to reframe my walls when I’m so close to making this fit, especially when I have 12 units to install.  I examined the combo AC unit and there’s no obvious way to reduce its width.

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  1. joshdurston | | #1

    I'm not an expert and maybe I'm misinterpreting what you're doing, but I would treat those wall openings like windows with all the usual framing/flashing around them (like headers, sill, etc).

    1. Expert Member
      NICK KEENAN | | #8

      This sounds like the correct answer.

      I'll throw in that rather than trying to squeeze the opening between two studs, put the opening directly over a stud, cut it, and frame out the opening. Skilled carpenters can do that in finished walls with a hole no bigger than the rough opening.

  2. MAinspector | | #2

    I would think 3/32" would be a non factor but couldn't you just add a stud next to the ones you are notching if you though it was an issue?

  3. onslow | | #3


    While even a 1/4" notch might not seriously cripple the stud, you need to think about what the studs are carrying. If you have placed roof trusses in alignment with the studs then I suggest the simplest option is to add a stud on either side of the ones framing the combo unit. That would also allow you to notch a bit more aggressively and make the installation less frustrating. Might also prevent unexpected vibrations from the combo units.

    In a different thread, many more qualified commenters opined that a certain house in Texas wouldn't fall down despite the presence of very questionable lumber. From my own practical experience, a certain wood butcher electrician hogged out 2" holes the length of the supporting walls of my family room. In fortunately very clean 2x4's. I moved out 25 years later with no cracks in the drywall. My conscience was clear thanks to my having become the next tear down in a newly spawned McMansion neighborhood.

    Your biggest concern might be getting blowback during the framing inspection.

  4. michaelbluejay | | #4

    Adding more vertical framing members generally means removing and replacing the wall coverings, at considerable effort. This is not new construction.

    Perhaps after shaving the studs I could sister some new 2x6s onto them, by pulling out the existing insulation and dropping the new sisters down to the floor plate. But I wouldn't be able to screw them at the bottom without removing the wall coverings, I'd have to settle for screwing them only at the top and using construction adhesive for the rest of the length.

  5. user-6623302 | | #5

    Notching the stud assumes everything is straight and exact. I will bet that is not the case. What is the wall covering? Might be better to plan on wall repairs.

  6. Expert Member
    BILL WICHERS | | #6

    3/32" isn't going to be a problem -- you can shave that much off with a hand plane. I've seen checking deeper than that in #2 graded lumber too which would tend to indicate it's OK.

    If this were a column, I would not exceed the max allowable code limitations worked out as a cross sectional area. If that's 25% of the width, that is no more than 1.3 square inches of material removed, but keep in mind that this isn't something I've had to deal with before so no guarantees.

    Generally if you need to modify a structural member outside of the code book tables and guides, you're into engineering territory and need to consult a structural engineer. The rule is "Think it's weird? Think you need it engineered."


  7. michaelbluejay | | #7

    Thank you all, especially Zephyr7. I've contacted an architect to see what he'll prescribe/sign off on. He might refer me to an engineer. I'll try to remember to post the conclusion here in case others have a similar issue or are just interested in the answer.

  8. michaelbluejay | | #9

    Here's what the architect said:

    (1) Studs are stronger across their depth than their width, which is good news for my application.

    (2) The main concern is the stud bowing left or right within the wall. The chance of this is lessened if there's sheathing. T1-11 siding helps, but not as much as sheathing.

    (3) For a 3-story house, I could notch as much as 3/8" into 2F studs before I need a sister.

    (4) For notch up to 3/4", remove the inside wall covering (not the T1-11 because cutting into it compromises its anti-racking strength), and sister in a stud that extends 18" above and below the notch, with six screws each in the areas above, below, and across from the notch, with PL-400 adhesive in the screw holes, then notch.

    1. Expert Member
      NICK KEENAN | | #10

      Did the architect happen to say anything about weatherproofing the hole in the side of the building? That seems like a much bigger concern than shaving a few sixteenths off of the studs.

      1. michaelbluejay | | #11

        Failing to weatherproof doesn't mean that your house could collapse, so I think getting the stud treatment right is a bigger concern. The architect mentioned that framing carpenters can't or won't measure their notching to a 1/16th of an inch so I should expect that they're gonna gouge out considerably more, despite whatever my orders are.

        As for the hole, what hole? You mean the for the AC? There are already existing holes for the existing ACs, I'm just enlarging the holes to accommodate the larger heat pump units. So I'm not adding to weatherization issues, except that the perimeter of the holes will be a little larger. I'm in Climate Zone 2 where it rarely freezes. The units are 80 lbs. and not easy to remove and reinstall for those few months when they're not needed, but I can simply put a cover over them in those months.

        1. Expert Member
          NICK KEENAN | | #12

          Failure to weatherproof absolutely can lead to your house collapsing. Not right away, but if water gets in the framing will rot and in time fail.

          In my climate if you cut a hole in the siding and didn't flash it and seal it you'd have it rotting out in a year or two.

          Are they under an overhang?

          1. michaelbluejay | | #13

            The house is 40 years old and I think had these openings from the beginning, so seems to be okay.

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