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  • Yet another closet flange question

    Hi Gents,

    Thought it would be a good idea to run this plan past you experts. I’m putting in a new bathroom with a tile floor, and want to get a solid closet flange installation. I have to put the tile over a Wonderboard substrate. I’m not too experienced with Wonderboard, but unfortunately this time I don’t have the vertical height available for a mud bed. The abs flange with stainless ring isn’t glued in yet so I can set the height properly.

    My problem is that the raw edge of Wonderboard seems to be pretty crumbly, and screws too close to the edge don't work well. Even with tile on it, I’m not happy about setting the closet flange over that stuff. I wish I had bought Hardibacker now, but it’s too late.

    My idea is to make a 7-1/2” square out of plywood with a hole in for the flange to sit on, and screw that to the plywood subflooring. I’ll actually stack & glue two pieces of 15/32 ply, which will set the top of the plywood at the same level (real close, anyway) as the finished tile. I’ll bring the wonderboard and tile right up to the plywood square. This way, the tile will be fully under the lip of the toilet pedestal. Of course, I’ll put a load of stainless screws to hold everything into the subfloor.

    Workable plan? Thanks in advance!

    -Andy

  • #2
    Re: Yet another closet flange question

    andy, not a bad idea, but make sure you keep the 3 and 9'oclock position within 1'' of the sides of the flange. otherwise it will show.

    the flange should be sitting on top of the finished floor. flush with the floor would require a thicker wax seal or a second seal.

    with plastic flanges and a metal adjustable ring, it's very important to properly secure the flange. stainless screws are a good/ wise choice.

    rick.
    phoebe it is

    Comment


    • #3
      Re: Yet another closet flange question

      Hi Rick,

      Thanks as usual for the help.

      I was also concerned about being inside the toilet so it won't show (that would be a disaster). My flange measures 7" diameter. I figure if I make the plywood 7-1/2 square, that's only about 1/4 away from the flange on either side, at 3 and 9 o'clock. A look at the toilet says it should all fit inside with room to spare.

      I'll double check the thickness stackup to make sure that the flange ends up at the right level to avoid having to get a thick seal or double seal. I should be able to get it within plus or minus an 1/8 without much trouble. Good enough to get by with a standard wax?? If I can't get it perfect, is it better to be 1/8 high or low? If you think it really needs to be perfect, I can do that too... just means a pass or two through the planer. But I can't imagine the wax would be that finicky.

      Yup, always stainless screws, and always as long as possible. Fortunately the entire subfloor is all new - no soft wood under there at all. I've never seen a flange come loose, but have seen non-stainless screws rust to the point of being almost completely gone.

      Thanks again! I'll go forward with the plan.

      -Andy

      Comment


      • #4
        Re: Yet another closet flange question

        Why not drill through the wonderboard and attach to the plywood subfloor? Less work and just as solid. 12X3" screws ought to do it.

        Comment


        • #5
          Re: Yet another closet flange question

          plumbus, that will also work fine for andy as long as the subfloor was cut to a pretty close tolerance. most of the time i see it's not as the carpenter typically uses a skill saw and over-cuts the plywood.

          if the ply is good, then just some spacers under the flange and inserted through the screws will work great. 1/2'' emt or copper would make a great spacer to guide the screws through.

          rick.
          phoebe it is

          Comment


          • #6
            Re: Yet another closet flange question

            Hi again guys,

            I would never in a million years trust wonderboard to hold the flange screws!! The plan was always to go all the way into the subfloor.I'm just aiming to get the most solid possible support under the flange, and don't want the edge of that wonderboard to crumble underneath it. It would likely be just fine. I'm sure most flanges are done by drilling through the cement board and screwing to the subfloor just as plumbus suggests.

            #12 x 3 is exactly the right size. The subfloor boards are 1-1/2 thick, the plywood is 3/4, and the tile stackup is another inch. So a 3" screw will be perfect, a 3-1/2 will poke through the underside of the subfloor. Nice call!

            My subfloor is good fit. The subfloor I tore out had a terribly sloppy square cutout done with a skilsaw, exactly as Rick said. I put in the new subfloor boards and plywood, then cut a clean (round) hole at the right rough in dimensions, and finally cut and glued the pipes together based on the proper location established by the hole. So the spacer idea would work.

            But, I just cut the plywood scrap and put the hole in with an adjustable holesaw on the drill press - it didn't take more than 10 minutes. I guess that's one advantage of working at your own home... you have access to all your tools! I decided that I won't screw the plywood square spacer to the floor until the final tiling is complete. That way I can plane it to put the flange exactly at the perfect height.... again, it's at my house, and the planer is sitting in the garage waiting to be fed some wood anyway!

            I do admit that have a serious tendency to overkill these things, but I think it will be a nice looking and solid installation.

            Thanks again, friends!! This is a great resource.

            -Andy

            Comment


            • #7
              Re: Yet another closet flange question

              a lot of times we just shim the flange up with peices of 3/4 copper cut to length, the tile guy will cut a square hole out of the backer and fill the void with thinset. it's only a problem if we don't tape the johnny bolt holes before they mud.
              No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

              Comment


              • #8
                Re: Yet another closet flange question

                done by now, and sure it will be fine, but if you really want to be bomber about it and you are going to whack out a chunk of ply and replace it with one with a nice precise hole, why not nail in a couple of 2-by's between whatever joists are already there right under the toilet while you've got room to do it? gives you something solid to nail your new chunk of subfloor to also.

                kudos to you for making it solid. I see a lot of rocking toilets that can't be made stable w/o major surgery because tightening the bolts just sucks the poorly secured flange up to the toilet.
                This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.

                Comment


                • #9
                  Re: Yet another closet flange question

                  Originally posted by Ace Sewer View Post
                  done by now, and sure it will be fine, but if you really want to be bomber about it and you are going to whack out a chunk of ply and replace it with one with a nice precise hole, why not nail in a couple of 2-by's between whatever joists are already there right under the toilet while you've got room to do it? gives you something solid to nail your new chunk of subfloor to also.

                  kudos to you for making it solid. I see a lot of rocking toilets that can't be made stable w/o major surgery because tightening the bolts just sucks the poorly secured flange up to the toilet.
                  Since you mentioned it...

                  On this project I rebuilt the entire floor structure, and replaced all the joists, using 2x6 everywhere - and about twice as many joists as originally present. The floor was pretty shoddily constructed originally. And I did put a "tic-tac-toe" grid around the toilet, but due to the waste and vent line routing and the pier locations, I couldn't get the grid right under the flange.

                  On top of the new joists are T&G 2x8 subfloor planks, with 3/4 ply on top of those.

                  I think it should be a good floor. Feels like a rock so far!
                  Last edited by Andy_M; 01-03-2010, 06:45 AM.

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