Need to drill into slab, how to avoid copper pipes?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Collin, Dec 30, 2005.

  1. Collin

    Collin New Member

    Messages:
    12
    Location:
    Austin, TX (Wells Branch)
    I am building a curb for a new tile shower. I want to screw a 2x4 into the slab to form the base of the curb. I'm really worried about hitting a copper pipe in the vicinity, as I will be drilling between the bathroom sink and the old tub/shower. Are there any precautions I can take to avoid hitting a copper pipe in my slab? Are copper pipes usually routed with only 90 degree bends? I will be using TapCon screws and be drilling down an inch or so.

    Collin
  2. Winslow

    Winslow Plumber

    Messages:
    450
    Location:
    Hawaii
    you should have no problems as long as you don't penetrate the slab. The pipes shouldn't be running in the slab, they usually penetrate the slab and run in the base course under it.
  3. Collin

    Collin New Member

    Messages:
    12
    Location:
    Austin, TX (Wells Branch)
    I thought they ran underneath the slab, but I excavated about 2 square feet of the slab around the PVC drain pipe (replaced 1 1/2" with 2"). That hole was only a few inches away from where the copper pipes come up from the slab (I didn't escavate around the copper pipes). I can reach underneath the slab where the copper pipes should come out but I can't feel them. Maybe they are just at an angle? I live in South Texas and have heard of copper pipe slab leaks. I thought that meant a copper pipe within the slab had leaked.

    I have attached a picture. The 2x4 on the right will be the new shower curb. There are actually 4 copper pipes. The sink and toilet are to the right. The street connection is further to the right.

    Attached Files:

  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,636
    Location:
    Cave Creek, Arizona
    pipes

    The copper tube/pipes are under the concrete and in any case would never be within an inch of the surface. If they were it would be almost impossible to bend them to a vertical orientation, and fittings are never used under the slab. "Slab leaks" are leaks in the piping below the slab.
  5. sulconst2

    sulconst2 New Member

    Messages:
    205
    Location:
    old bridge nj
    use treated lumber for the curb. 3 high.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,636
    Location:
    Cave Creek, Arizona
    curb

    One thing you will probably notice after you complete the shower is that the wood in the curb expands and contracts from humidity and the grout will crack where it meets the walls.
  7. Collin

    Collin New Member

    Messages:
    12
    Location:
    Austin, TX (Wells Branch)
    Thanks for the tips, guys. I thought about using treated wood for the curb but heard that it tends to warp as it dries out. I have done a few outdoor projects using treated wood and I can definitely see warpage. I do realize the conditions outdoors are not the same as indoors. I've been reading a lot at johnbridges.com and the consensus there seems to be to use non-treated wood, screwed to the concrete, with about 3/4" of fat mud on the top and sides. The fat mud is strong enough to withstand or prevent any distortions of the wood. I plan on using 3 stacked 2x4s for the curb.

    hj, I intend to use caulk instead of grout at all expansion joints.

    Thanks again,

    Collin
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,013
    Location:
    New England
    Check out www.johnbridge.com for your tiling. It is suggested that for a curb on a slab to NOT use wood - use concrete pavers or brick and lay them up like a wall, then your liner and tile. While the wood shouldn't get wet from the shower, it is not at all uncommon for the wood to absorb some from the slab, depending on the seasons. Make sure your liner is on a preslope - do NOT put it on the flat floor. On the flat floor may keep it from leaking, but it will do nothing to prevent accumulated water from sitting under the tile and smelling like a swamp after awhile.
  9. Collin

    Collin New Member

    Messages:
    12
    Location:
    Austin, TX (Wells Branch)
    Jim, thanks for the reply. I have been using www.johnbridge.com as a guide. John himself suggested screwing 2x4s to a slab in the following post.

    http://johnbridge.com/vbulletin/showthread.php?t=13818

    Would a vapor barrier between the 2x4 and slab help? There are a couple other posts about this. I think the consensus there is that the 3/4" of mortar on the tops and sides of the 2x4 curb will prevent movement.

    Collin
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,013
    Location:
    New England
    John seems to prefer bricks or pavers on concrete slabs. If you go with treated wood, get kiln dried stuff (after treatment). As noted, the wood should not get wet from the shower, but any moisture that comes up through the slab (maybe none-depends on where you live) could cause them to swell. If you spilled a bunch of water outside of the shower, it could get to the wood, too. So, you decide which way you should go. If it were a wood subfloor, the 2xs would work as well as anything. Concrete, I'm not sure (not much experience in that area at all).
  11. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    If your talking about drain pipe here you can't do this it will cause a problem.
  12. Collin

    Collin New Member

    Messages:
    12
    Location:
    Austin, TX (Wells Branch)
    Hi Cass, can you clarify your last post? The original pipe I replaced was under the slab the the new 2" pipe I put in is also under the slab. I backfilled with the original dirt and plan to top off with about 4" of Quikrete.
  13. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Did you replace a peice if 1.5" pipe with 2" pipe? Did you upsize the pipe?
  14. Collin

    Collin New Member

    Messages:
    12
    Location:
    Austin, TX (Wells Branch)
    Cass, I originally had a tub/shower combo. I am replacing this with a tiled shower. The tub had a 1 1/2" drain pipe connected to a 2" p trap, connected to a 2" drain pipe. I took out all the 1 1/2" pipe and the 2" p trap and replaced with 2" pipe and p trap (I moved the drain to the center of the shower and the p trap is now directly under the new shower drain). There is no more 1 1/2" pipe. After reading this forum, I know better :)
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