I am cutting a new outlet in the wall between my living room and dining room. Below is an unfinished garage with completely accessible joists where I can run wire. There are double joists directly below the sole plate behind the wall.

I will build a jig for the 3/4" spade bit at the required angle (I calculated to be 18°). At the top of the sole plate the 3/4" hole has the required 1.25" clearance within the sole plate.

The "hole" in the joist below is at the top edge so it ought to be considered a "notch". The height of the notch is, uh, some old horse... around 2.5"... which is more than 1/6 the height of the 2x12...

What do you think? Can I do this?

Top view:

Top view

Bottom view:

Bottom view


Stepping away from the pen and paper for a bit, and thinking practically, I could easily cut a 2" notch in the joist, then my spade bit would fit in the notch easily and at a better angle. I don't have to cut the notch with the spade bit, you know.

  • There should be no reason to use a 3/4" hole to run a single jacketed electrical cable. For a 12AWG cable a 5/8" hole should be more than enough.
    – Michael Karas
    Mar 9, 2019 at 9:47

1 Answer 1


First off that's an amazing question!

Most codes would frown upon touching the top or the bottom of a joist in this fashion.

That being said it's probably totally fine to make a tiny hole in the manner you are describing. I've seen some awful things done that caused no problems and if I saw your scenario on a job I wouldn't even notice.


2.5" is pretty big I would definitely notice that.

  • A 7/8"x18" ship auger bit would perform this task in fine form. The subsequent joist weakening would be negligible.
    – Paul Logan
    Mar 9, 2019 at 4:00
  • Thanks for the advice. I'll minimize the notch and follow up with the auger bit.
    – 000
    Mar 9, 2019 at 6:26
  • 2
    WHAT??? You say, “...it’s probably totally fine...” You’re giving advice to over cut/drill the top edge (the compression edge) by 25% beyond what is allowed by code (1/6 of 11.25” joist height) and you’re not acknowledging that the double joist probably means it’s a bearing wall above. All, because, as you say, “...I wouldn’t even notice.” ITS NOT ABOUT NOTICING THE NOTCH. It’s about over stressing the support joists under the bearing wall above. Don’t you think more information is needed?
    – Lee Sam
    Mar 9, 2019 at 12:53
  • @LeeSam yes you are right I was paying more attention to the picture and it looks like the intention is a small borehole to run a wire. I noticed after, the OP mentioned a 2.5"cut, that's definitely a bad idea and this topic should be addressed further.
    – Joe Fala
    Mar 9, 2019 at 15:26
  • With a 5/8" hole at a less aggressive angle, I worked out a scenario which results in a 30° angle and a 1.25" notch.
    – 000
    Mar 10, 2019 at 3:10

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