So I was in my attic last night, about to drill some holes in the top of the wall to run CAT 6 ethernet cables down the wall. I found above the wall is two parallel ceiling joists that are completely blocking the wall that I'm trying to run cables to. I don't want to drill into the joists and risk structural integrity damage, so does anyone know of a way to workaround this without drilling into the joists?

  • 1
    How tall are the joists? Jul 11, 2019 at 15:32
  • @Harper the joists are fairly long, about 15 feet or more, and the ceiling is about 5' up from the ceiling floor Jul 11, 2019 at 15:41
  • 1
    So you have a doubled up joist sitting on top of the wall so you can't drill through the top plate of the wall? Can you drill just under the joists at an angle so you still end up in the wall cavity buy don't make much of a hole in the joists?
    – JPhi1618
    Jul 11, 2019 at 15:58
  • I might be able to do that @JPhi1618. I'm trying to avoid putting holes in the joists if possible though (especially in the top or bottom of the joists because that severely impacts the integrity of the joists) Jul 11, 2019 at 16:02
  • @jsotola updated the question to include cable type Jul 12, 2019 at 19:17

1 Answer 1


A doubled joist is 3" wide.

A standard 2x4 is 3.5" wide.

You have a lip on one edge or the other.

Can you not start your hole on this lip taking perhaps a nibble out of the corner of the joist?

Joists support. If this double joist has a wall under it, what is it supporting that the wall itself isn't sufficient.

In normal configuration the bottom of a joist is in tension, while the top is in compression. This assumes that it's being supported at the ends. Gets more complicated when it's supported at multiple points.

Taking a chunk out of the bottom, where it is already resting on the wall below isn't going to make the building collapse. Because of that wall, there is no tension on the bottom of the joist.

  • 1
    Hey @Sherwood, I was able to find a small gap in the backside that I used to drill through, although I did dig into the joist just a little bit about 1/8". Unfortunately The two 2x4's were lying on-top without any spaces to drill. I bit the bullet and took a small chunk out but like you said, they are being supported by the existing wall frame as well as other places in my house. Thanks! Jul 16, 2019 at 15:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.