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  • Plumbing on a slab foundation

    Want advise on how to connect the DWV into the main pipe under a slab.

    Is it OK to cut a hole in the slab and dig down to the main pipe to connect?

    Or can you extend the DWV pipe through the outside wall and
    then dig down to the main pipe to connect?

    Any advise would be appreciated.

  • #2
    Re: Plumbing on a slab foundation

    need some job specifics.

    are you adding on a new bathroom and need to connect to the existing?

    depending on the job, you might need to cut the slab to connect to the existing. or you might be able to dig around the structure and tie in at the front / rear where it exits.

    what size pipe do you need? toilet requires a 3'' min. almost everything else is 2''.

    need more info to steer you right

    rick.
    phoebe it is

    Comment


    • #3
      Re: Plumbing on a slab foundation

      The DWV is the drain pipe for a washing machine which will be on the
      inside wall with the pipe going to the outside wall. It is 2" and
      needs to either go through the outside wall and around the structure
      of the house or maybe break through the slab???
      I think it might be easier to go through the outside wall and tie in
      at the point where the main line can be easily connected.

      Thanks

      Comment


      • #4
        Re: Plumbing on a slab foundation

        Originally posted by plumber_dlm View Post
        The DWV is the drain pipe for a washing machine which will be on the
        inside wall with the pipe going to the outside wall. It is 2" and
        needs to either go through the outside wall and around the structure
        of the house or maybe break through the slab???
        I think it might be easier to go through the outside wall and tie in
        at the point where the main line can be easily connected.

        Thanks
        This is nothing short of a matter of your local code.
        Here, we can't go through an exterior foundation with anything less than 4"...with exceptions for a locally approved dry-well for a laundry.

        Your code could be substantially different, if it's illegal it would be an issue when/if you resell the home.

        Comment


        • #5
          Re: Plumbing on a slab foundation

          Originally posted by plumber_dlm View Post
          or maybe break through the slab???

          Not sure how old the house/slab is, but if you opt to go through the slab, you will want to be sure it is not a post tension slab first. Or have xrays taken.

          JMTCW...
          Still enjoying all 10 fingers!

          Comment


          • #6
            Re: Plumbing on a slab foundation

            Originally posted by wwsmith View Post
            Not sure how old the house/slab is, but if you opt to go through the slab, you will want to be sure it is not a post tension slab first. Or have xrays taken.

            JMTCW...
            I don't think I've ever seen that in a residence.
            Have had a scare or two coring commercial floors though.

            Comment


            • #7
              Re: Plumbing on a slab foundation

              The house is over 50 years old.

              Comment


              • #8
                Re: Plumbing on a slab foundation

                Originally posted by wwsmith View Post
                Not sure how old the house/slab is, but if you opt to go through the slab, you will want to be sure it is not a post tension slab first. Or have xrays taken.

                JMTCW...
                Most excellent perception

                Comment


                • #9
                  Re: Plumbing on a slab foundation

                  the way i read this is you want to run the pipe through the out side wall then tie into main

                  you cant run a drain above ground out side it will freeze
                  you have to cut the slab and go outside below the frost line then tie into the main ,make sure you are on the right side of the house trap .
                  Charlie

                  My seek the peek fundraiser page
                  http://observatory.mountwashington.o...nal&fr_id=1040


                  http://www.mountwashington.org/weather/conditions.php

                  new work pictures 12/09
                  http://public.fotki.com/hvachawk/

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                  • #10
                    Re: Plumbing on a slab foundation

                    A fifty year old house should not have anything in the slab.

                    There are 2 things to watch for, the tension wire and the membrain for methane gas.

                    If it helps you sleep better, xray is always a possible method.

                    I had a 17' long trench x '9' in depth to dig to repair a collapsed sewer at a local AMC, they signed the waver not to xray, I knew something was there, they said there was no time, long story short, I have pictures of conduit in the concrete, 17 total lines cut.

                    The sawcut guy (idiot) didn't stop, even after the 3rd blade, he kept going.
                    sigpic

                    Robert

                    Comment


                    • #11
                      Re: Plumbing on a slab foundation

                      there will not be post tension cable in that 50 year old residential slab.

                      most likely only wire mesh.

                      but why destroy/ demo in the house when you have an outside wall.

                      unless the tie in is only a few feet away from the work area.

                      x-ray is out of the question.

                      x-rays are used for coring holes, not taking pictures of an entire trench.

                      ground penetrating radar is the way to go, plus you don't have to evacuate the house and get a second mortgage to pay for the service.

                      if you do saw cut, don't cut all the way through the slab, as the lazy electricians never bury their conduit. typically only laying on the sand or on the rebar. but this is usually commercial jobs and not residential work.

                      a simple ridgid locator, scout, navitrack will pick up on 60 cycle electricity running below the slab.

                      rick.
                      phoebe it is

                      Comment


                      • #12
                        Re: Plumbing on a slab foundation

                        AAAHHH,DANG-IT.
                        I'm always using the wrong terminology.The locator guy was teasing me all day when we were working together last month.

                        RADAR!!!!
                        SORRY

                        Comment


                        • #13
                          Re: Plumbing on a slab foundation

                          Originally posted by drtyhands View Post
                          AAAHHH,DANG-IT.
                          I'm always using the wrong terminology.The locator guy was teasing me all day when we were working together last month.

                          RADAR!!!!
                          SORRY
                          Just a reminder then. . .Rick is "special"
                          I love my plumber

                          "My Hero"

                          Welcome, Phoebe Jacqueline!

                          Comment


                          • #14
                            Re: Plumbing on a slab foundation

                            I always hear x ray also, never radar

                            oh well, learn something new all day
                            sigpic

                            Robert

                            Comment


                            • #15
                              Re: Plumbing on a slab foundation

                              Originally posted by MrsSeatDown View Post
                              Just a reminder then. . .Rick is "special"
                              OOOOHHHHH YEAAHHHH.....RIIGHHT.
                              Got it

                              Comment

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