Does Flooring Go Under the Toilet Flange?

Installing a toilet correctly will save you from having to fix a water damaged floor in the future. If a toilet flange is not installed properly, you are basically rolling the dice, hoping that some day down the line you won’t have any issues. It’s not just about the connection of the toilet to flange but the constant weight of someone moving an improper connection around which can cause a leak.

For proper installation, a toilet flange must always be installed and secured on top of the finished floor. Toilets are manufactured to allow a toilet flange to sit up under the toilet, so the bottom of the flange and bottom of the toilet are at the same height. This allows for a proper connection when a wax seal is installed in between the toilet and flange.

There are instances where a vinyl floor is installed right up to the side of the flange and typically this isn’t a problem. Usually, a wax ring is thick enough that it will cover the distance between the toilet and flange, even if the floor is raised up ¼” or so. It’s when you install a thicker floor and butt it up to the side of a flange that you can run into problems.

In the rest of this article, I’ll try to cover the different scenarios you might run into when installing a new flange and or toilet.

How High Should the Toilet Flange Sit Above the Floor?

If the toilet flange is being installed before the finished floor, then you must know how thick your flooring will be.

Having this information will allow you to install the flange so the underside of the flange will be right at the top expected height of your finished floor. Let me give you an example from a toilet I just installed in my basement.

In my basement, the 3” toilet drainage pipe was sitting above the concrete floor approximately 4”. This was obviously way too high to install a flange.

To know how high the toilet flange should be means you need to know how thick your flooring will be. In my case, I used a dri-core subfloor which is ⅝” thick and vinyl plank flooring which measures ⅜” thick.

This means the subfloor and finish flooring sits 1 ½” on top of the concrete. This also means that the underside of the toilet flange lip should be 1 ½” above the concrete. If it’s any lower, you won’t be able to get the vinyl plank floor underneath and any higher, then you will have to shim the flange. I would err on being a hair higher than being too low if need be.

For anyone with a similar installation, I recommend securing the flange through the floor and dri-core and right into the concrete at least a ½” or more. If it’s just into the subfloor, you might get some slight wobble.

Can the Toilet Flange be Lower than the Floor?

I mentioned at the beginning of this article that you could get away with butting laminate flooring up to the side of the flange as the wax ring should be able to make up the difference.

What if the toilet flange is below the finished floor? Can a toilet be installed that way?

As much as it isn’t recommended and if you just can’t find a way to get the flange higher or toilet lower, you can still work with this problem. There are two options here.

First option: You can use two wax rings on top of each other and make sure the bottom wax ring has a plastic extension on it. This means you will need one traditional style wax ring and one wax ring that has a plastic extension on one side. The plastic part will sit on the bottom of the two wax rings extending into the ABS pipe.

I like to make sure the wax rings are warm before installing as they are easier to work with and form to ensure you get a 100% seal.

Second Option: There are toilet flange extension kits made primarily for this issue. These kits are installed using the existing kit to attach too and from what I hear do a fine job. I have not used one so I can’t offer too much up on this topic. I’d be comfortable using one of these, however.

Can a Toilet Flange be Too High?

On the opposite side of a toilet flange being too low, what if it happens to be installed too high?

To determine, if a toilet flange is too high if there is any space between the top of the finished floor and the underside of the flange then it is too high.

The problem with this is the toilet will rock back and forth. From side to side or front to back depending on where you apply pressure when you sit on it.

This can pose a couple of serious problems. The toilet bowl itself can crack and the flange can crack as well. Either way, you’re going to have water damage if this happens.

There is an easy way to remedy this if you can’t lower the flange by installing it correctly.

I have done this many times in the past and it works like a charm. Using cedar shims, slide them under the toilet in the front back and sides. They are pushed in far enough when they feel snug.

If any of the shims are sticking out of the bottom of the toilet, just score them with a utility knife flush with the bowl or mark with a pencil. Pull the shims back out and cut off the excess. Once done, just slide them back under the toilet bowl.

Of course, just leaving a gap might not look that great especially if shims are exposed. You can finish this up nicely by applying a bead of bathroom silicone around the bottom of the toilet where the gap is. If you got the shims pushed under perfectly, nobody will ever know they are there.

Should the Toilet Flange Be on Top of Tile?

Regardless of how the floor is finished, you must install the toilet flange on top of the finished flooring.

Even if the floor is tile, the flange still needs to be on top of it. If you are not sure about how to secure through the ceramic tile, you need to get yourself a drill bit that is rated for drilling through ceramic or whatever the tile is.

Conclusion

In conclusion, I just want to point out the importance of having the flange sitting on top of finished flooring.

The biggest danger of not doing that will be having a toilet leak. If the leak isn’t noticed right away, the water will damage the subfloor and joists and maybe more – it just depends on your home.

Install the flange properly in the first place and you never have to worry about that.