My floor joists do have pre-cut knockouts - however the joists are not all lined up so the holes vary. I need to run a few lines perpendicular to my joists. I am thinking about drilling holes near each other 1/4" larger than my pex to run my lines. The alternative is to install them just below the joists. I am unsure of my future basement ceiling. Is it worth fighting the holes and trying to get holes drilled in a straight path for the pex to snake through or better to just clip it on the bottom of the joists?

  • It's PEX, so I'm not sure why (other than sloppy workmanship on the part of the framing crew) it concerns you that the knockout holes don't exactly line up. PEX wiggles really well. Knock out the ones nearest the line you want to follow, and wiggle away.
    – Ecnerwal
    Nov 23, 2015 at 2:35
  • True, but each knockout is 20 or 24" apart. To run hot and cold would be a mess. No matter what, a hole must be drilled for one of the lines. I can wiggle it through, but I think it would look like poor workmanship and also get in the way of drains or other objects.
    – CCCBuilder
    Nov 23, 2015 at 3:15

2 Answers 2


Just line up the holes and run the line. You are thinking about this too much. The last thing you want to do is put these below the joists.

  • if you have people in your basement this would make it really easy to just reach up and hang on or whatever.

  • if you move these in the future it will assuredly be harder - and why set yourself up to move something.

  • the PEX could even get in the way of a drop ceiling.

  • the PEX is more secure in the joists


You said "I am unsure of my future basement ceiling."

If that is the case you may want to put them up in the joists in case usually want to out in a hard ceiling (something I would recommend against).

Otherwise just run them on the bottom of the joists and plan on a drop ceiling if you want one later.

  • 1
    I have 8'8" of clearance...I am thinking a drop ceiling is a good plan - but this is in the bathroom/utility room so perhaps it would have moisture issues with a conventional drop ceiling.
    – CCCBuilder
    Nov 23, 2015 at 2:19
  • Interior bathrooms without a window require an exhaust fan by code. And if you have a family member that likes long showers you will want a high volume exhaust fan. You may need ceiling panels that are moisture resistant or look at a different style of ceiling.
    – ArchonOSX
    Nov 23, 2015 at 2:22
  • 1
    Which is why I think drop ceiling wouldn't work out. Guess I will see if there are moisture resistant tiles. The simple option could be just to fur out the ceiling a couple inches and install rock on that...but it's permanent.
    – CCCBuilder
    Nov 23, 2015 at 2:31

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