Space needed for new flange

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Kevz, Nov 15, 2005.

  1. Kevz

    Kevz New Member

    Messages:
    26
    Location:
    Ohio
    I am having a plumber come and replace the cast iron flange in our house once our floor is in. Old was cracked, he chiseled off all of it. Right now just the pipe in the floor, we are now replacing the floor with a new tile floor. I am at the stage of laying down the cement board and was wondering how much space I need to give him around the stack to be able to put in the new flange.

    Wasn't sure if it went on the inside or outside.. And I don't want him to have to start breaking away tile on the new floor if I got too close. At this point if I needed to cutaway some of the plywood subfloor to give him a little more room around it would be easy, just don't want him smacking away at the tile after I finish up.

    Thanks for your time.
  2. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Toilet flanges are made both ways, to go inside or outside. Outside alowes more of the pipe to be used. Leave the plumber 3/8" around the outside of the pipe. This will give the flange enough floor to rest on and enough floor to screw the flange on to. I would also have the plumber change as much of the CI (cast iron) pipe as he can to plastic. Have him go back to the stack if possible.
    Last edited: Nov 16, 2005
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,481
    Location:
    Cave Creek, Arizona
    space

    1. A cast iron flange needs at least 3/4" around the pipe, and if your opening is larger the flange will still cover it.
    2. I would never change cast iron to plastic, unless there was an extremely good reason to.
  4. Kevz

    Kevz New Member

    Messages:
    26
    Location:
    Ohio
    I was under the impression it would be better to have a new flange put on with lead on the current cast iron pipe.. And in doing that I wouldn't need to screw anything into the floor... Or am I wrong? Would it still need to be screwed down?

    So if I give him 3/4" clearance all around the pipe he should have no problems?

    Thanks again
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,888
    Location:
    New England
    As I understand it (and I'm not a pro), if the pipe is 4", you can use an internal or external flange. If it is a 3" pipe, it must be external. Since the trap is normally not much over 2", either should work. So, depending on what you have, will determine how much clearance you must provide (from none to what HJ said - and he IS a pro). Assuming you are going to have him lead it in, then you'd probably use an external one (I think).
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,481
    Location:
    Cave Creek, Arizona
    flange

    In the past 55+ years, I have screwed down very few flanges and none of them were cast iron, if that answers your question.
  7. dubldare

    dubldare Plumber/Gasfitter

    Messages:
    286
    Location:
    MN/ND
    A properly fastened closet flange will eliminate a wobbly toilet and prolong the life of your new floor.
  8. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    How do you prevent the flange from being pulled off the floor when you tighten the bolts? CI might not pull off but plastic will as I have run into this problem a few times. The flange not being screwed down lets the toilet move.
    Last edited: Nov 16, 2005
  9. Kevz

    Kevz New Member

    Messages:
    26
    Location:
    Ohio
    My CI stack is 4" I can cut the subfloor out to give 3/4" of an around almost all of the pipe, but the pipe comes up next to a joist. There I will not have 3/4" all the way down. Is that enough room? It had a CI flange on originally, so I am assuming it can be replaced.

    I would rather not have the plumber drilling through the tile, I just keep picturing bad things happening. But I also want it done correctly. Anything I should be making sure he does/uses when replacing it?

    Thanks again
  10. Gary Swart

    Gary Swart In the Trades

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    7,328
    Location:
    Yakima WA
    Remember, even if he has to cut some of the tile, that will be under the toilet and will not been seen. I wouldn'ts do too much more than you already have, wait until the plumber gets there and sees what, if anything, still has to be done. Chances are he can do it quicker and easier than you anyway.
  11. Kevz

    Kevz New Member

    Messages:
    26
    Location:
    Ohio
    I would just much rather give him enough room so he doesn't have to cut or break away tile once I set it. Even if that part is under the toilet, if it happened to crack a tile or the thinset it could continue outside of where the toilet sits.
  12. plumber1

    plumber1 Plumber

    Messages:
    1,423
    Location:
    Florida
    flange

    I agree with H J.
    I keep saying, you never get bad advice from H J.
    If you raising your floor you can buy a cast iron flange that is an inch or two longer than the standard one which is probably 11/2 " deep.
    Get the tile guy a cast iron closet flange to use as a guide.......your gonna need it anyway and then you will lead and oakum the flange down. Don't worry about screwing the flange down, it isn't going anywhere.
    Last edited: Nov 18, 2005
  13. Kevz

    Kevz New Member

    Messages:
    26
    Location:
    Ohio
    I am the tile guy. Had never tiled a floor without a flange though. Plumber told me to just go and lay my floor and he will come when its done and it will be connected to the CI pipe and will sit on top of the finished floor..

    Not sure what I need the flange now for? As long as I give him room around the pipe he would need, but don't want to remove too much because it sits on top of the tile.. Correct?

    My plan is to open up the subfloor 3/4" all the way around the stack like HJ suggested. Then laying my CBU and tiling to that point and then having the plumber come in to do his stuff. Sound right?
  14. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,888
    Location:
    New England
    If you get the flange in advance of installing it, you can size things as you want, notch the tile so that you don't have to drill holes to anchor it, at least through the tile (they put those holes in the flange for a reason), and never have to drill through the tile. Course, a properly installed tile should not crack if it is drilled with the proper tools and the tile has 100% thinset coverage on the back as it should, either. My unprofessional opinion.
  15. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,481
    Location:
    Cave Creek, Arizona
    flange

    You have never installed a tile floor without a flange? You must not do many new homes because we never install the flange until after the floor is in place. Even when an inspector wants the flanges in place during a prior inspection, they are only slid on so they can be removed for tiling.
  16. Kevz

    Kevz New Member

    Messages:
    26
    Location:
    Ohio
    I don't do tile for a living, I have just laid tile for either myself, my parents, friends. Think I have done like 9 jobs. Only a few bathrooms and the it was a tile replacement job, so the flange stayed in place.
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