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I wanted to run a CAT6 cable simply from a first floor room to the second floor room directly above it. I drilled through the bottom plate in the wall on the 2nd floor as shown. I first used a 1/2 in bit, but it was not long enough so I bought a 5/16 one that was 1 ft. Unfortunately I messed up with the first hole and had to stop because due to a slight angle it started poking through the dry wall on the other side (just open air into the house entryway). Seems that the 1 ft one was not long enough either surprisingly because there is still not a thru hole. I'm most worried about whether this is now unsafe, but if not, what is the problem here? Do I need an even longer bit?

UPDATE: I took out the drywall in the room directly below this, and found a large wooden beam spanning that wall, from at least ceiling level to 1ft down. That wall also has a large opening for a folding door. I fear I really shouldn’t have made those holes— maybe that huge beam is there to compensate for the opening, i.e. lack of studs? What do you think? On the bright side, I got the CAT6 cable out through an exterior wall and ran it up the brick and it looks and works quite good!

Purple is where I know for sure there is wood, green star is directly below the drill holes:

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  • Please show us a picture of the opened wall - where you have pulled the drywall off. Not that we don't trust your description, but a picture being worth 1000 words and all...
    – FreeMan
    Commented Feb 10, 2021 at 12:22
  • @FreeMan there it is! Commented Feb 10, 2021 at 16:17

2 Answers 2


First - you have done nothing that will harm your house other than give a few bugs a raceway, but this is the 50th raceway, not the 1st.

Second - you will have to open it up from below to see what is there. You went through bottom plate and subfloor. You probably (almost definitely not) don't need a longer bit.

  • 1
    I hate working blind, and you're already in for drywall repair where you came out of the wall so, yes, open the darn thing up. If you are blindly drilling down into a stud, you will go a long ways before coming out. Know where you are drilling, and what's there to hit, and miss, and miss it. +1
    – Ecnerwal
    Commented Feb 5, 2021 at 15:39
  • I opened it up from the room below as you suggested, check my updates in the main post, I’m still a little worried Commented Feb 10, 2021 at 5:14
  • Add pictures please and you ran cat6 outside on brick? What did you run it through?
    – DMoore
    Commented Feb 10, 2021 at 5:31
  • Pic added. Nothing actually. Someone had installed a phone cable and a coax cable on that brick wall long before I owned a house. Probably not the most weatherproof idea but whatever! Commented Feb 10, 2021 at 11:56

A few extra holes in the plates are not unsafe, so no -- you didn't harm your house.

Guessing here, but your plate+subfloor+joist height+top plate of first floor is more than 12". Get an 18" installer bit (with a hole near the tip) and use it to fish the wire. Try to make sure you end up centered in the plate below.

Edit to say that you need to cut a bit more drywall back to understand that header and how to get through it. Maybe you'll get lucky and it won't go much further to the left. Maybe you'll be less lucky and have to drill through it. Any way you slice it, you need more drywall gone, and a large patch is about the same as a small patch.

  • 1
    I agree, a 12" bit is not enough for fishing wire between floors at the best of times and certainly not through an oversized header. Combining a comment above with this answer: Know what you're drilling through and get a bit that is long enough. Also .. consider wifi. :)
    – jay613
    Commented Feb 10, 2021 at 13:53

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