How to deal with a joist in the way of where I need to run a pipe

central-vacuumjoistsstructural

I'm in the process of installing central vac lines (2" OD) in a finished house, and I am trying to run a line into the upstairs hallway. I have removed drywall in the garage below and drilled a hole down using an installer's bit, and found the hallway wall is sitting directly over top of a joist.

Entry point and hopefully future location of inlet
Looking down inside wall, drill bit visible
Looking up at drill bit and joist from garage

This is an ideal location as it is the only spot that allows me to reach every upstairs room. Any further and I have to open up walls on inside spaces, which I want to avoid.

There's a not-as-ideal alternative on a nearby adjacent wall (about 3' away) that would allow me to come down between joists, but the hose only reaches halfway into one of the bathrooms, so I'd prefer the original location if possible.

Is there a safe way to make this work? The challenge is that I will have to drill through a bit more of the joist to fit the 2" pipe in (as I already inadvertently did..).

Couple more images:

Looking up at garage ceiling
Full
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Full

EDIT 2013-05-07:

I drilled a second pilot hole right at the edge of the bottom plate, and decided I had enough room to come in on an angle with a 2" hole saw. The "notch" on the 2×8 isn't any deeper than 1/4", you can actually still see the original pilot hole where I came through the joist (the groove nearest the camera). I'll need to use some flex pipe to hook this up because of the angle, but that is no big deal.

2" hole through bottom plate

Do I still need to sister another 2×8 to this? How significantly is this really affecting the strength of the joist?

EDIT 2013-05-10

Got it done, using 2" ID flex pipe (typically used to hook up those under-cabinet vacuum sweep inlets). Thanks everyone.

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final connection done

Best Answer

My answer is to cut your two inch hole as close to your drywall as possible. In the picture you went right down the middle and barely hit the joist. Methinks that you could drill right along the side and have to barely notch out the joist below. Might not even have to notch all the way through it. No reason for vac lines to have to be centered in your wall. Use the notch guidelines I found to help further.

  • Notches in floor joists may occur in the top or bottom of the member but may not be located in the middle third of the span.
  • A notch may not exceed one-sixth of the depth of the joist except at the very end where it may be one-fourth of the joist depth.
  • The length of joist notches cannot exceed one-third of the depth of the member.
  • Holes bored in joists must not be larger than one-third the depth of the joists.
  • Holes cannot be located within two inches of the top or bottom edge of the member, or to any other hole located in the member.
  • Holes cannot be located within 2" of any notch.

Below is a helpful chart that provides actual notch and hole size limitations for 2x4, 2x6, 2x8, 2x10 and 2x12 joists. It should be noted that limitations on the allowable notching and boring of wood joist are meant to retain the structural and functional integrity of the member.

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