There are two things necessary to prevent a toilet from leaking at the flange: a good flange, and a good seal between the flange and the toilet. As I'm not a plumber, I'm looking for how best to ensure no leaks in my repair.

Here's the current state of the 60 year old cast iron flange. It was so old and the wax ring had dried out and I had to use an old wood chisel to get down to the flange. I wire brushed with a drill and threw some enamel to prevent future corrosion.

Unfortunately, the notch on the right had been leaking and corroded the flange for the bolt into a V-shape. For a few bucks, I bought a steel plate and used some epoxy to attach it to the under side of the flange driving it upwards with some shims. I'm just going to use my stick welder to fill in and grind down, and touch up the enamel so the flange lasts another 60 years. Should I augment the flange in some other way, and if not, is a newer waxless solution maybe necessary since the flange isn't in the best condition?

enter image description here

  • which one you want to chose from
    – Traveler
    Dec 6, 2022 at 18:56
  • 1
    Epoxy. Shims. Welding. That's a lot of work when they make flange repair kits...
    – FreeMan
    Dec 7, 2022 at 13:21
  • @FreeMan Work is opportunity. Besides, this my hobby. For me, a lot of work is tracing down a null pointer exception in a compiler stack in 20 year old architecture.
    – J D
    Dec 8, 2022 at 17:48
  • I do not envy you that work!
    – FreeMan
    Dec 8, 2022 at 17:53

3 Answers 3


"The bottom lip of the toilet flange should sit flush with the finished floor. If the floor is uneven, then no seal is going to work."

That is simply not true. Sure in a perfect world the flange is always at the perfect height. If not then Super DIY Man (who by the way has every tool ever made) fixes it.


Hundreds of thousands of weekend DIYers pull toilets and change the floor in their baths and don't or can't afford to call a plumber to get that perfect flange.


The new waxless toilet seals have come along. Some are better than others. One in particular The Saniseal is well designed and I have used for about 15 years without a single issue or need to replace them. I have them on hand for the homes I buy and rehab, so we can tear out a bath and put a toilet back to use while we are working. Then pull it again and finish the floor and install a new toilet, reusing the saniseal, because they are designed to do just that.

enter image description here

  • Kudos to the reusability, and seating a toilet temporarily. I'll definitely remember that next time around.
    – J D
    Dec 7, 2022 at 7:21
  • The bottom lip of the toilet flange should sit flush with the finished floor. If the floor is uneven, then no seal is going to work. comes from a reputable professional plumber Plumb Smart, Inc.. And who are you, a weekend DIY ?
    – Traveler
    Dec 7, 2022 at 8:55
  • 2
    No, @Ruskes , I don't work most weekends. I have spent 54 years rehabbing and remodeling homes. Started with my fathers apartment building. Been doing it long before Bob Vila ever had a show about it. You learn some things over 50 years.
    – RMDman
    Dec 7, 2022 at 12:35
  • Don't know how long Ruskes has been doing it, but don't forget, he was "knowitall" for a while!
    – FreeMan
    Dec 8, 2022 at 17:54

Since the current cast iron flange is already missing its two bolt sections at top and bottom in your photo (the V notch is probably for a screw to secure the flange securely to the subfloor), why not replace the flange. Here's one type of flange that seals to the inside of the waste pipe once you cut/chip off the original damaged flange:

enter image description here

Once you screw the new flange securely to the subfloor, you can use normal toilet bolts and any type of wax or waxless seal you want, with good results for stability and sealing.

  • Something to reconsider. I guess as a clueless non-plumber, I have concerns that the horn will negatively impact the inlet diameter. But I do like the idea of securing the flange to the subfloor. The old flange isn't.
    – J D
    Dec 7, 2022 at 7:27
  • There are all kinds of different repair flanges. I just picked this example as relatively easy to install, but you're right that it would slightly decrease the diameter where it seals to the pipe.
    – Armand
    Dec 7, 2022 at 19:27

The plumbing community is actually divided on that. Some swear and stick with wax rings. Others like new fancy stuff. All of them have their pros and cons. In theory, the wax ring should last the lifetime of the toilet, or certainly 20 to 30 years.


The key is:

The bottom lip of the toilet flange should sit flush with the finished floor. If the floor is uneven, then no seal is going to work.

  • Thanks for the article. It certainly seems to call out BS and highlight the importance of the flange height.
    – J D
    Dec 7, 2022 at 7:24

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