Can I route PEX/copper pipe through joists?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by lurch, Jun 24, 2009.

  1. lurch

    lurch New Member

    Messages:
    15
    Location:
    NJ
    I'm partway through replacing my old forced air furnace with baseboard and I'd also like to upgrade my 1/2" main supply with 3/4". I see that a lot of the electrical cable in my 50's home is routed through the joists - is this allowed for plumbing?

    I assume not as all of the plumbing I see is hung with a gap between the top of the pipe and the joist. However some of the new lines my plumber put in for the Hot water heater are attached directly to the joist. What is the code for running plumbing lines wrt the joists? The water supply lines are copper - the baseboard are PEX.
  2. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    This would likely fall under the building code. And it entirely depends on the type of floor joists you have.

    If you have a standard 2x? floor joist then where I am from you can run water lines through them. The issue isn't with the water lines it's with where you drill the holes. Run the water lines through the CENTER of the joist and don't drill holes bigger then you have too.
  3. iminaquagmire

    iminaquagmire DIY Senior Member

    Messages:
    207
  4. 99k

    99k Radon Contractor and Water Treatment

    Messages:
    460
    Location:
    Fairfield Co.,Connecticut
    There's important info left off the guide, not only can the hole dia. not exceed 1/3 the width of the beam but it is restricted in location to the first 1/3 of length (either end). The middle 1/3 is off limits.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,653
    Location:
    Cave Creek, Arizona
    boring

    It does refer to it, but that restriction is for notching, not holes through the joist. A properly drilled hole will cause minimum degradation of the joist strength. If holes weakened the structure, heavy equipment hauling trailers would not have multiple holes cut in their main frame channels.
  6. lurch

    lurch New Member

    Messages:
    15
    Location:
    NJ
    Thanks guys - I have 2x8 joists - and the holes drilled for the NM cable looks to adhere to those guidelines.

    I was not aware you could do that.
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,025
    Location:
    New England
    The vast majority of the strength in any beam is the top and bottom cords. Look at an engineered I-joist...the middle is thin plywood.
  8. 99k

    99k Radon Contractor and Water Treatment

    Messages:
    460
    Location:
    Fairfield Co.,Connecticut
    Thanks HJ, I just looked at the IPC and I stand corrected:rolleyes:
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