OK, after doing some research I believe the best way to install a toilet is on a flange that is attached on top of a finished floor, and if a flange is too low or too high there are ways to accommodate it. But I need some expert advice in a situation where I may have some flexibility, but not to do it the ideal way. Let me explain.
Here is my current situation, and I'd rather not try to change it: There is solid, stable subfloor and concrete backer board that surround an ABS drain with a 4" inner diameter. The drain is clean of wax or adhesives and there is no flange currently attached. There is solid, level tile here too but the opening in the tile around the drain is about 8 inches. So a standard flange can fit inside this opening and be bolted/screwed down securely through the backerboard and into the subfloor. But this would result in the flange being lower than it should be. The surrounding tile would be level with the top of the flange (approximately) instead of the bottom, as it would be if the tile were cut closer to the drain and the flange could go on top of it.
So I have some options, but not unlimited options. What is the best approach at this point? Thanks.
Edit for additional clarification: by "not wanting to change my situation" I mean I do not want to retile the area; I need to work with the situation as it is. A commenter suggested I just install the flange, then use a known solution for situations where the flange is below the finished floor level. That's a good suggestion. An alternative might be to install the flange in some way where it would not be too low to begin with, which might be possible because I have the luxury of not having yet installed any flange. So I want to know which of these approaches is better, and, what specific technique or product is suggested for that approach. I hope this makes my question more clear.

  • 1
    “Here is my current situation, and I'd rather not try to change it” “there is no flange currently attached” how are you going to attach a toilet if you’re unwilling to change your situation by installing a flange. Attaching the flange and using one of the several methods of dealing with a flange that is too low would be the answer if you are willing to change your situation
    – Alaska Man
    Feb 5, 2018 at 2:48
  • Alaska man, thank you. Based on your comment I have edited my question to make it more clear what I meant.
    – David H
    Feb 5, 2018 at 6:55

1 Answer 1


Since there is no flange installed yet you could just fill in the void with materials such as plywood or hardy backer to bring it up close to the level of The existing floor then solidly secure the new flange with long screws.

The wax ring mounting system of a toilet to a flange is fairly forgiving so you do not have to be precise. You could leave it the way it is and use a extra thick ring or you could fill it as I suggested and use a single thickness ring or one of the newer rubber gasket options. Having the flange above the level of the tile floor is not necessarily the right thing as this could be problematic in getting the toilet to sit tight to the tile floor without rocking . I would shoot for having the top of the flange be at the same level as the tile floor( or slightly lower ). You want enough gap for the wax ring or mounting system but not so high that it interferes with the toilet.

There is more than one way to skin a cat, there is no one correct answer for your question.

Many times when I lay a new bathroom tile floor I am able to unscrew the flange and lift it up and slide the new cement board underneath it but sometimes that is not possible and I have to use a thicker wax ring or a flange extender.

I saw a new product on this old house that was a thick squishy foam type ring that looks much nicer to use then wax.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.