Toilet flange height

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by joewadd, May 18, 2013.

  1. joewadd

    joewadd New Member

    Messages:
    4
    Location:
    Winchester CA
    Hello,
    I am installing a new toilet in my shop with cement floor so where should the correct height of the flange be?

    My plastic flange is almost a 1/2" thick .450 to be exact so should the bottom of the flange rest on the top of the cement surface?

    Someone told me the top of the flange should be level with the floor surface that doesn't seem right.

    Thanks for any help.
    Joe
  2. cwhyu2

    cwhyu2 Consultant

    Messages:
    1,348
    Location:
    Cincinnati OH
    Bottom of flange on top of finished floor.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,139
    Location:
    New England
    IF you haven't installed the flange yet, please do not use the all plastic one- pick one that has a SS metal ring. You'll want to anchor it with some lead anchors or maybe some Tapcons. The all plastic ones are a problem waiting to happen. Should someone bump the toilet, that small plastic slot will likely crack. And yes, all toilet flanges are designed to sit on TOP of the FINISHED floor, and to be securely fastened. Now, something like a CI flange on CI pipe in a concrete floor should be strong enough without further fastening, but that isn't what you have.
  4. Hammerlane

    Hammerlane Member

    Messages:
    252
    Location:
    Ohio
    Usually a debate about this issue. .But I agree bottom of flange on top of finished floor. #1 below.

    Attached Files:

    Last edited: May 19, 2013
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,831
    Location:
    Cave Creek, Arizona
    What's to debate? The only proper way is to have the flange on top of the finished floor.
  6. joewadd

    joewadd New Member

    Messages:
    4
    Location:
    Winchester CA
    The only flange I could find at Lowes was the plastic with a 3" slip in area and my pipe is 3" so I had to put a coupler to connect the flange to pipe.

    I haven't mounted the flange yet so I can change to a better one, but I did glue the coupler to the 3" pipe. If I need to cut off the coupler I only have 2 1/8 straight left to work with.

    The issue I had was finding a flange to adapt to the 3" pipe the current one is the same size as the pipe3".

    If I get a flange to go over the 3" pipe you have the lip or edge of the pipe to restrict flow, not that it would, I thought smooth transition was better.
  7. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,358
    Location:
    Yakima WA
    When you have to use a 3" flange, it should NOT fit inside the drainpipe. This cuts the diameter of the pipe too much. Suggest you find a better supply house for materials and get the recommended flange.
  8. joewadd

    joewadd New Member

    Messages:
    4
    Location:
    Winchester CA
    I picked up an Oatey brand flange that has a stainless flange that spins on plastic and it will go over the 3" pipe, is this the one to use.
  9. wjcandee

    wjcandee Wise One

    Messages:
    1,894
    Location:
    New York, NY
    There ya go.
  10. how2do

    how2do Handy Tom

    Messages:
    7
    Location:
    Pawleys Island, SC
    As far as flow and any restriction to the waste line...that's a misnomer...the maximum diameter of most toilet outlets is 2 inches...some I have seen are 2-1/4" but that all depends on the manufacturer's casting mold. The correct method is to mount the toilet flange on top of the finished floor. Below is a cutaway showing the distance between the toilet and flange...

    Set-Rite_Cutaway.jpg
    Last edited: May 19, 2013
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