Should Toilet Flange Be Flush With Floor: Subfloor Or Tile?

Whether you’re renovating an existing bathroom or building a new one from scratch, it is crucial to install your toilet right. To do that, you must nail the toilet flange installation. And this leads us to the question: should the toilet flange be flush with the floor or sit on top of the tile? What if you want to install the flange before installing the flooring? 

For a correct installation, you should always place the toilet flange on top of the tile. The flange’s optimum height is about ¼ inches on top of the finished floor. Installing the flange on the subfloor or flush with the tile may result in incorrect sealing and lead to a wobbly and leaky toilet. 

Should Toilet Flange Be Flush With Floor?

The toilet flange should not be flush with the floor, but it must be level to allow for a correct installation. A difference in height between one side of the flange and the other could compromise your toilet’s balance. For this reason, you should make sure the floor around the toilet is level or use a filler to ensure a level fit of the flange.

Should you install the toilet flange before or after the tile?

One of the things homeowners trying to rough in a toilet on their own find confusing is the fact that some plumbers install the toilet flange on the subfloor. Why do they do that? Should the toilet flange really sit on top of the tile, or can it sit on the subfloor, too?

While some plumbers may install the toilet flange on the subfloor, they generally only do that if the homeowner hasn’t selected and installed the flooring yet. Contractors may choose a subfloor installation so that they can call the work done and ask for a paycheck.

However, you shouldn’t install the toilet flange on the subfloor. That’s because the flange must raise above the floor at a height of about ¼ inches (up to ½ inches sometimes, if you have a vintage toilet), and the only way to achieve that is by installing it on top of the finished floor.

The raised edge of the flange allows the toilet to sit perfectly on top of it after you’ve added the wax ring, creating a watertight seal. Moreover, the flange adds stability and improves the toilet’s balance – but only if it is level. Otherwise, it won’t prevent the toilet from rocking and leaking.

How To Install A Toilet Flange On A Tile Floor

We already mentioned that you should always install the toilet flange after the tile. In the rare cases when a contractor installed it before tiling, you can adjust its height with flange spacers. With this in mind, here’s how to install the toilet flange yourself.

What You’ll Need

  • Toilet flange
  • Tapcon screws
  • Hammer drill
  • ¼-inch masonry drill bit
  • Multi-tool
  • Tape measure
  • Putty knife
  • Screwdriver
  • Rubber gloves

1. Pick the correct toilet flange

While all toilet flanges look alike, they come in different sizes to fit various drain pipe sizes. Installing a flange that fits seamlessly into the drain pipe is essential. Otherwise, it may be hard to create a watertight seal.

To pick the correct size, measure your exposed drain pipe’s internal diameter, then buy a slightly smaller flange than the measured diameter

Note: Some closet flanges designed to install on smaller diameter drain pipes may have a diameter larger than the pipe. In this case, the pipe should fit inside the flange and not the other way around, and you’ll have to glue the flange and pipe together to prevent leaks.

2. Position the flange 

Positioning the flange correctly could be challenging, but you can use a trick to get it right: install the toilet’s T-bolts first

The T-bolts are two plastic or metal bolts installed upside-down on the flange so that their shaft sticks up. When installing the toilet, these bolts pass through the water closet’s mounting holes, allowing you to fasten it to the flange with nuts. 

While you should generally install the T-bolts after the flange is in position, mounting them beforehand can help you visualize the toilet placement and position the flange correctly into the drain

Once you’ve installed the bolts, position the flange so that they are parallel with the back wall on both sides of the flange. Make sure the bolts are placed at an equal distance from the back wall. Push the flange until its rubber seal grips firmly inside the drain pipe. Pushing the flange should require you to use some force.

3. Fasten the flange 

Once you have installed the flange, it is essential to keep it from turning. To do that, you have to fasten it to the floor.

Drill mounting holes through the floors with your ¼-inch drill bit. Bore four holes directly through the mounting holes around the flange’s ring. You can then secure the flange to the floor with Tapcon screws or similar fasteners. 

As mentioned above, it is crucial to mount the flange level against the floor. Otherwise, the toilet might rock back and forth after installation. Check with a level and adjust as necessary before installing the toilet.


Can A Toilet Flange Sit Below The Tile?

In a typical toilet installation, the flange should sit on top of the finished floor and not below the tile. However, when renovating a bathroom, you may want to add new flooring without removing the old floors first. 

If the new floor goes above the edge of the flange – or if your flange was accidentally installed on the subfloor – you can use a flange extender to reach the recommended ¼ inches above the floor.

Flange extenders are not universal, so you should get a model that fits perfectly on top of your flange. Some brands may allow you to choose between metal and plastic extenders. The plastic ones are a better choice since they won’t be affected by rust or corrosion.

Toilet Flange Sits 1/2 Inches Above Floor – What To Do? 

Another issue you may be faced with when installing a new toilet is a toilet flange that sits too high above the floor.

As a general rule, a flange that sits ½ inches above the floor can create similar problems to a flange installed under the floor level: your toilet may leak and rock back and forth when using it.

The easiest way to deal with the issue is by replacing the flange with a new one, installing it at the correct height. If that’s not possible, you can make up for the height difference.

You can do this by filling the gap between the bottom of the toilet and the floor with grout or adding a plywood base to the toilet before installing it on the flange

If the flange sits too high because the drain pipe raises above floor level, you can solve the issue by cutting the drain pipe and installing a new flange. If you decide to do this, keep in mind that the bottom of the flange should sit flush with the floor – this should help you measure and cut the pipe correctly.

Does A Toilet Flange Need To Be Screwed To The Floor?

Yes, the toilet flange has to be screwed or bolted to the floor. Skipping this step means that the flange could move as you’re installing or using the toilet. 

If it moves during installation, you may end up with a toilet that isn’t parallel to the back wall, and you may have issues when mounting the tank. If it moves when you’re using the toilet, the rocking motion could break the wax ring and lead to leaks.

Do You Tile Around The Toilet Or Under It?

Normally, you should tile under the toilet. Considering that the flange must be installed on top of the finished floor, it goes without saying that the toilet sits on top of the finished floor as well. However, if you want to replace the bathroom floor without taking off the old tiles, you may tile around the toilet.

There are a few things to consider before doing this, though. Tiling around the floor generally means that you’ll have to find a toilet model identical to the one you currently have should you ever have to replace the existing toilet. 

Not only will the tile around the water closet not accommodate another toilet size or design, but the flange will also be placed below floor level. The extra thickness added by the new tile means that another toilet model may not sit correctly on top of the flange, leading to an unbalanced and potentially leaky installation.

To prevent issues, it is recommended to remove the toilet, tile the entire bathroom, and then install a new flange and the toilet on top of the finished floor if you plan a bathroom remodeling. If the drain pipe is cut too low, use flange extenders for a correct installation.

Final Thoughts 

A toilet flange should raise ¼ inches above the finished floor. Installing it on the subfloor or flush with the floor can lead to leaks and balance problems. We hope this guide can help you during your bathroom construction or renovation.

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