Copper Joints under Slab

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by DME, Feb 7, 2007.

  1. DME

    DME New Member

    Messages:
    3
    I know it's not preferred that you have a joint under a slab. But, if there is no way to avoid it what is the most reliable method. I am considering going with flare joints. It's 1/2 copper lines. Any thoughts?
  2. srdenny

    srdenny Plumbing Contractor

    Messages:
    361
    Location:
    SF Peninsula
    Silver soldering is a code approved, below slab method of joining copper tube and fittings.
  3. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    I don't remember what the code is on flared joints under slab. Myself, I wouldn't do it because there will never be access to take it apart even if you wanted to. As for any kind of metal line under slab... my experience says that it needs to be protected from the chemicals of the concrete and should be in a plastic sleeve to protect the metal.
  4. kordts

    kordts In the Trades

    Messages:
    551
    Location:
    exurban Chicago
    Most codes let you either flare or braze under slabs.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,048
    Location:
    Cave Creek, Arizona
    joints

    I always perfer flare over brazing, if the fittings are available. Brazing is "destructive" in that it removes the temper from the fittings, making them "flexible" and subject to cracking and breaking.
  6. Racer814

    Racer814 New Member

    Messages:
    124
    silver solder.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,048
    Location:
    Cave Creek, Arizona
    silver

    Silver solder also requires a red hot joint, which also detempers the fitting.
  8. Randyj

    Randyj Master Plumber

    Messages:
    1,047
    Location:
    Alabama
    Interesting... if using appropriate materials and properly making the weld and protecting it then it should be a moot argument when the concrete is poured...but at least now I know.

    Using the "proper material and method" only means it was done to the least highest standard. The "proper" steel gas line, is a very poor material to bury in the ground, but an inspector will approve the installation. I have had 1/2" lines silver soldered to a 2 x 1/2 tee, and the branch of the tee broke off because the fitting's "hardness"/temper had been destroyed by making the joint.
    Last edited by a moderator: Feb 8, 2007
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