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  • Cast Iron Closet Flange Height

    I'm remodeling the bathroom in a 1950's home. I've got an existing cast iron pipe stub and closet flange that currently sits too high for the planned finished floor.

    From the pictures you can see the cast iron pipe stub with the flange, oakum (sitting inside the flange), and lead removed.

    The 3/4" board you see sitting next to the pipe stub was placed there to simulate the new 3/4" ply sub floor that will eventually be installed. The highest point on the pipe stub extends 2" above that board and is also where the bottom of the flange was before it had been removed.

    I'm estimating that only 5/8" of that 2" gap will be taken up by the cement board underlayment and tile, which will sit on top of the sub floor, potentially leaving a 1-3/8" (or more) gap between the finished floor and bottom of the flange.

    I understand that the bottom of the flange needs to sit flush with the finished floor. What I'm not sure about is at what height does the top of the pipe need to be to ensure that happens and ensure a good fit/seal? Should it be cut so that it will be flush with the finished floor?... sub floor?... other?

    One thing that should probably be factored in is that I'm planning to use one of those twist and set cast iron replacement closet flanges, like the one shown here:

    Oatey Twist N Set Cast Iron Replacement Closet Flange

    Even though I was able to salvage the original cast iron flange during demo, I'm just not confident enough that I could figure out how to work the oakum and lead sufficiently to achieve a proper seal/fit.

    To be quite honest, I have no clue at this point how the new flange is going to work either, but I thought it might be easier to figure out and work with (once I actually go out and buy one) while still accomplishing the end result.

    Anyway, what I need assistance factoring in is whether or not I should be able to get the replacement flange onto the pipe such that the bottom of the flange would be at the same height as the top of the pipe or should I expect it to sit higher? This, to me, would factor into what height the top of the pipe needs to be. Perhaps one way to find out is to just go buy a flange and do a test fit.

    Your thoughts/comments/suggestions would be greatly appreciated.

    Thanks,
    Tom
    Attached Files

  • #2
    Re: Cast Iron Closet Flange Height

    The stub up needs only be as high as the hub of the flange.
    I would not use the PVC insert flange.
    Rather, I would go with a regular CI flange, screwed to the
    finished floor, and packed tightly with lead wool.
    Requires no special tools and will tightly secure the flange
    to the pipe.

    Comment


    • #3
      Re: Cast Iron Closet Flange Height

      Jim, thanks for your reply. Based on your input and posts I've seen in other threads in this forum and other forums, I've shelved the idea of using the PVC insert.

      As far as using a regular CI flange, would the existing CI flange work? The reason I ask is that, as you may notice from the pictures, the existing flange has no holes or notches to anchor the flange to the floor. It only has notches for the bolts that anchor the toilet to the flange.

      Presuming for a moment that the existing flange is sufficient (ie. it could just rest on the finished floor and the lead wool would be adequate hold it in place), would I need to pack oakum tight into the base of the flange first before packing the lead wool in? A comment I read (either on this forum or another) mentioned that the oakum is what provides the water tight seal, while the lead is primarily there to keep the flange in place.

      Now, taking the flip side and presuming that the existing flange is not sufficient, then I'm looking at purchasing a new CI closet flange. All of the flanges that I've found so far have the holes/notches to anchor the flange to the floor, but are compression flanges and do not require lead wool (and oakum?). For example:

      Code Blue Cast Iron Closet Flange

      Oatey 165 Cast Iron Closet Flange

      It would seem to me that the newer flange would be the way to go, considering it can be anchored to the floor, which the existing flange cannot (without some custom modification ). However, I'm not sure how well those compression seals hold up.

      Comments? Suggestions?

      Thanks,
      Tom

      Comment


      • #4
        Re: Cast Iron Closet Flange Height

        nothing wrong with using an instant set closet flange. these use a compression ring/ rubber to tighten to the pipe. usually 3 or 4 bolts to evenly tighten to the pipe. do not use an internal compression ring on 3'' pipe. unless you poop like a rabbit

        the only problem is the old pipe needs to be fairly clean and it definitely needs to be properly bolted to the floor. otherwise it will move and leak.

        the pipe has to be flush with the top of the flange. easiest way to cut it flush is with a grinder and cut off wheel. for me an internal cutter set to cut flush.

        just be careful when cutting or grinding.
        phoebe it is

        Comment


        • #5
          Re: Cast Iron Closet Flange Height

          The no caulk type flange will be fine.


          For better or worse, I'm just old school.

          Comment


          • #6
            Re: Cast Iron Closet Flange Height

            Rick, thanks for your comments. I think I have a pretty clear idea now on what I need to do.

            I was curious whether the horizontal ridges on the top portion on the pipe stub (rust and crud covered in the bottom right corner of the attached picture) or that vertical ridge running along the inside bend of the pipe would pose any problem for the outside compression flange.

            I don't anticipate the horizontal ridges to be a problem after I clean them up (probably use a wire brush or wire wheel on a drill) since they might seem to seat within the ridges in the rubber gasket of the compression flange.

            The one that concerns me is that vertical ridge. Would it be advisable to grind that ridge down a bit so that it would be flush (or as close to it as possible without getting carried away) with the horizontal ridges or might that compromise the structural integrity of the pipe?

            Thanks,
            Tom
            Attached Files

            Comment


            • #7
              Re: Cast Iron Closet Flange Height

              Originally posted by PLUMBER RICK View Post
              nothing wrong with using an instant set closet flange. these use a compression ring/ rubber to tighten to the pipe. usually 3 or 4 bolts to evenly tighten to the pipe. do not use an internal compression ring on 3'' pipe. unless you poop like a rabbit

              the only problem is the old pipe needs to be fairly clean and it definitely needs to be properly bolted to the floor. otherwise it will move and leak.

              the pipe has to be flush with the top of the flange. easiest way to cut it flush is with a grinder and cut off wheel. for me an internal cutter set to cut flush.

              just be careful when cutting or grinding.
              With service weight pipe, which has a smaller o.d. than no hub, an instant set ring can tighten all the way down and not completely seal, or a tightening bolt can snap.

              Comment


              • #8
                Re: Cast Iron Closet Flange Height

                That's an ugly looking cast iron riser. Grind those edges down some before you put the subfloor in.

                When you break it or just get tired of dealing with it, look me up. We service Silver Spring

                Comment


                • #9
                  Re: Cast Iron Closet Flange Height

                  Oatey makes a twist and set in cast iron that *may* work for what you are doing.
                  You will still need to bolt it down once you set your finished floor in.
                  Do you have enough room to snap that off and put in a pvc riser instead?
                  What is that 2" threaded in..will it be trouble down the road?
                  Might be a good time to lose some of that old pipe.

                  Comment


                  • #10
                    Re: Cast Iron Closet Flange Height

                    Flat vented !
                    I can build anything You want , if you draw a picture of it , on the back of a big enough check .

                    Comment


                    • #11
                      Re: Cast Iron Closet Flange Height

                      I vote vent stack and a tub or sink washing in....
                      Not code here like that.
                      Tom,what are we looking at?

                      Comment


                      • #12
                        Re: Cast Iron Closet Flange Height

                        based on this closeup photo, i would caulk on a cast iron flange.

                        i doubt that a compression type flange will seal on that rough of a pipe.

                        you'll need oakum and lead, plus the tools to pour the joint.

                        simple for the oldtimers, scary for the new guys

                        rick.
                        Last edited by PLUMBER RICK; 09-23-2009, 09:35 AM.
                        phoebe it is

                        Comment

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