Installing new toilet flange in concrete

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by alwaysfine, Apr 29, 2010.

  1. alwaysfine

    alwaysfine New Member

    Messages:
    9
    Location:
    new jersey
    I am installing a new bathroom in my basement. I have cut the concrete and am now installing all drainage and vent lines but am unsure what the best way is to install the closet flange. I am roughing in all sewage lines now. After all lines are in I will refill dirt and refinish any removed concrete. I will have tile on the floor. Should I set the flange even with my concrete floor prior to tiling? Even with the finished floor after tiling? or just extend the pvc pipe and not finish it until all tile is done and I am ready to set the toilet? Also what do I anchor the flange to? Do I drop in bolts while replacing the concrete or drill out for Tapcons later? Thanks for any help in this area.
    Last edited: Apr 29, 2010
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,230
    Location:
    Cave Creek, Arizona
    IF you have the capability of installing the drains AND vents PROPERLY, then your question should not even need to be asked. How about a picture of what you have done so we can critique it.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    The proper place for the flange is on TOP of the FINISHED floor. Depending on the size pipe you used, you may be able to use an inside mount flange (if you have 4"), then you could essentially leave it long, then cut it off after finishing the floor. The flange can be screwed into the floor. It's easier if you notch the tile so you don't have to drill through them. If your drain under the slab is 3", it is my understanding you can use a 4x3 closet bend (is that the right name?), which would let you use an inside mount.
  4. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,395
    Location:
    Yakima WA
    You have 2 excellent answers to your question. There is little to add except to share my preference for anchoring into concrete. I use lead sleeves with #12 sheet metal screws rather than Tapcons. While there is no question on the strength of Tapcons, they are more HD than you need for a toilet flange and are more difficult to install (IMHO) You still must drill holes into the concrete and notching the tile would be a good idea. I use a 5/16" SDS drill bit in a small rotor hammer drill to drill the holes for the sleeves. This is drills holes almost as easily a into wood. The sleeves and screws will provide ample holding power for a flange. I use stainless steel screws for toilet flanges, just regular steel for mounting shelves, outlet boxes, and etc.. A word of caution when installing the flange. Make certain it is orients so the flange bolts are in proper alignment, and to reiterate JD's advice about the size of the flange. If your drain line is only 3", use a flange that fits on the outside of the pipe. The inside fitting flanges reduces the interior diameter of the pipe too much. A 4" drain allows you to go with either and inside or outside fitting flange. And to reinforce HJ's remarks, do make certain you have vented properly and that you have used the proper fitting and that they are installed correctly.
  5. alwaysfine

    alwaysfine New Member

    Messages:
    9
    Location:
    new jersey
    Thanks for the replies. I have added the pics of what I am doing for your review. I am adding a sewage pump with a 3" line from toilet to pump. Vanity drains down and the vent goes up from there. It will meet the vent from the sewage pump and go up to the roof when complete. The other pipe (p trap) is for the shower. All are dry fit and any suggestions would be appreciated before I glue. Thanks again.

    Attached Files:

  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,230
    Location:
    Cave Creek, Arizona
    The sink drain arm is too long for 1 1/2" pipe, unless your code allows longer than 42". The 2" 45 looks like a "pressure" fitting not a drainage one which, if so, is not a good idea. I might have installed the underfloor differently and saved some concrete cutting, but your layout will work, and I would NEVER use an all plastic flange like the one you have.
    Last edited: Apr 30, 2010
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    Now that you've cut everything, when you start to glue it together, you will find you are short. It is almost impossible to bottom out a fitting in a dry socket - they are called interference fits for a reason. WHen you add the cement after the cleaner/primer, the surface softens, and then the pipe will fit deeper into the socket than you can normally force it. You could lose 1/2" or more per fitting. Dry fitting pvc is (nearly) a waste of time If you do manage to dry fit a pipe into a socket all the way to the bottom, it will be a major bear to remove it so you can glue it up.
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