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Thread: Getting ready to set toilet.......

  1. #1

    Default Getting ready to set toilet.......


    I am getting ready to set my toilet in the basement and I got a question. but first a little background.

    Bathroom is in the basement on concrete floor, tile is done, and the flange is sitting on top of the tile. The 4" pipe coming out of the concrete is completely cemented in and cannot move and the flange is glued in. All plumbing is PVC, flange is PVC as well.

    Now the question. How important is it to screw the flange to the floor? I could understant the importance if it were on a wooden subfloor, but when the pipe is cemented in and cannot move is it necessary?

    I am a little apprehensive to drill the concrete arround the flange, and use some Tapcons at this point for a couple of reasons.

    1. Tapcons usually break
    2. Warping the flange by over tightening a Tapcon.
    3. Drilling into the pipe below the concrete (not sure exactly how thick the concrete is around the flange)

    I don't think that it will be a problem if I don't secure the flange, the toilet set level and did not rock when I dry fit it. I also tried to pry on the flange with a pry bay and it did not rock or move in the slightest.

    Any way thought I would ask to see if anyone had any thoughts.


  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    You should be okay with what you have. Depending on the type of flange (plastic, cast iron, etc.), keep in mind that while the flange itself may not move, it is weakest where the T-slots are for the closet bolts. While the flange may not move, depending on the strength of the flange itself, not having the rim anchored may risk breaking it. Normally, this would only occur if you overtightend the bolts while mounting, or if it got knocked, say if someone fell against it. Depending on the material, that kind of a thing may not matter one way or the other.

    One of the pros that sees maybe hundreds or thousands of these things in a career will have some better insight.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    In the Trades Gary Swart's Avatar
    Join Date
    Sep 2004
    Yakima WA


    I agree with Jim. As long as the flange is setting solidly on the concrete, it's not going anywhere. Just a note on anchoring to concrete. I am not a great fan of Tapcons. What I prefer is to drill a hole, insert a lead ferrell, and then a screw. I use stainless steel screws when there is a chance of moisture. They're quick and easy to install, and they hold very well. I've anchored electrical boxes to walls, 2x4s to walls and floors, toilet flanges, and door sills this way.

  4. #4


    I agree the lead ferrell's work a ton better. Problem is I don't think I can get them in through the flange. I should have put them in before I glued the flange in place and after I set the tile.

    Another good option is Red Heads. They hold very well for securing walls to the concrete floor. And they are a lot safer that a Ramset.

    Thanks for the info.


  5. #5
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default flange

    The only problem with not securing a plastic flange is that over time the constant upward pull of the bolts will distort it at the bolt slots and possibly eventually break.

  6. #6
    Homeowner geniescience's Avatar
    Join Date
    Nov 2005
    humid summers hot, humid winters cold

    Default plastic anchors in concrete

    i love heavy duty lead anchors in concrete. When there is a need to support real heavy duty weight pressure or shock. I love the spring loaded ones that you can hang a truck off of. I've used the passive lead anchors too.

    Not the case here. Today this situation is the opposite. A sitting on the floor weight not going anywhere. Hmmm, i think the suggestions made so far were too heavy duty.

    I'd use plastic. I've done it before, but I'm not a professional and I don't have decades of experience.

    How I'd use plastic: I'd screw stainless screws into slim plastic sleeves dropped into a drilled hole. Then, to be real sure and to add that extra security and peace of mind, I'd add a little cement product (like grout or thinset) on top right where the plastic anchor ends below the floor level of the cement or tile. This locks the screw in a cement-to-cement, or cement-to-tile, bond, holding that screw in place so tight it'll never be able to move if it gets bumped. Repeat for the next screw, etc. Now each screw is taking only a portion of shock when a bump happens. Then the toilet itself is siliconed or caulked in place around its edge, so any eventual movement is restricted to a micrometer range, like a vibration.

    I've done this before. I've even used plastic to hold the pivots in a pivoting shower door, both on the top -- and the bottom where all the weight and movement are! There is also a lot of silicone and epoxy grout holding the pivot hardware in place.


  7. #7

    Default Finished setting toilet

    Thanks for all the help, it was much appreciated. What I finally ended up doing was using some plastic anchors and some stainless steel screws. The holes in the flange were big enough to allow me to get a 1/4" masonary bit through and then the plastic anchors did not have a flange on them so I could pound them into the hole. Then I used some 2" #12 stainless steel screws to secure it to the concrete.

    It is not going anywhere! Thanks for the tip on the plastic anchors geniescience, They worked great.

    Thanks again.


  8. #8
    DIY scratch-pad engineer leejosepho's Avatar
    Join Date
    Nov 2006
    200 miles south of Little Rock


    I got in a little late here, but I believe the most important issue is having the toilet anchored so it will not easily tip or turn. One possibility might have been to simply drill right on through the flange that is already solid and screw studs into lead anchors so the toilet could be bolted (with acorn nuts) directly to the floor.


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