What is a Toilet Flange? What to Know About Closet Flanges

Last Updated on August 2, 2023 by toilethaven

A toilet flange is a piece of pipe fitting that connects the bottom of the toilet to the drainpipe. It also secures the toilet firmly on the floor using bolts.

Toilet flanges are also known as closet flanges. This is because flush toilets were commonly called water closets in the past. Old Toilet flanges are made of cast iron, but modern ones are made of PVC or ABS.

The function of a toilet/closet flange is to secure the toilet on the floor firmly. It has 2 slots which allow toilet mounting blots to be hooked and tightened against it using nuts. Toilet flanges are secure on the flooring using screws after being slid into the toilet drain line.

Four screws are used to hold the flange firmly on the floor. There are 2 opposite slots on the top of the toilet flange where you put in the toilet bolts. A toilet has two holes on each side of its base where the bolts are driven through. Nuts and washers are used to tighten the toilet in place.

A wax ring is normally installed between the toilet flange and the bottom of the toilet. This creates a water-tight and airtight seal that prevents flush water and sewer gases from leaking from the bottom of the toilet. If you ever notice water pooling around your toilet, it is a sign that the wax ring is not sealing.

An alternative to a wax ring is a rubber gasket seal. This gasket works the same way as a wax ring but is less messy/gross.

Toilet Flange Replacement

How do you know if your toilet flange needs to be replaced?

  1. If you notice your toilet leaking from the bottom.
  2. When your toilet is rocking/wobbling.
  3. After you have remodeled your bathroom.

When most people see water pooling around the base of their toilet, they first think of their wax ring, and somehow they are right. A toilet leaking at the base indicates that the wax ring is not sealing but could also signify a deep-lying problem, like a broken flange.

 If you have a wobbly toilet, it is either caused by loose toilet bolts, uneven floor, or a broken flange. The constant rocking of the toilet will, after some time, break the wax ring seal resulting in a leaking toilet.

When remodeling a bathroom or installing a new toilet, most people prefer to replace the old closet flange with a new one. This way, you don’t need to replace it after a few years/months. When you replace a toilet flange, you must also replace the wax ring. A wax ring cannot be reused.

Replacing a toilet flange is a simple DIY you should not pay a plumber to do. Here is a detailed guide on how to replace a toilet flange.

Toilet Flange Extender

A toilet flange should be flushed off the bathroom floor or a ¼ inch above it. The toilet can press strongly on the wax ring to form a tight seal. If the flange is too low, you will have a leaking toilet. Some people opt to double stack wax rings, but it doesn’t for long. So what can you use to remedy a flange that is too low below the flooring?

If your toilet flange is too low off the floor after a bathroom remodel or poor workmanship, you will need to install a toilet flange extender. Toilet flange extenders are installed on top of the existing flange in order to raise it to the desired height.

While installing toilet flange extenders, you may install the spacer rings or some that look like a normal flange but have a smaller diameter to fit inside the existing flange. The space rings are designed with different thicknesses to help you gain the desired height.

Remember to buy long toilet bolts to use with the flange extenders. While using the space rings, apply silicone underneath the ring and the top of the flange to create a water-tight seal.

Toilet Flange Sizes

Image Source: Plumbing Supply

1. Standard 4 x 3 flange

Most toilet flanges have a standard 4 x 3-inch size. The top of the flange where the toilet sits is wider with a 4-inch diameter, while the bottom part, which goes into the drainpipe, is 3 inches in diameter.

2. 3-Inch Flange

This is a uniform toilet flange meaning that the top and bottom diameters are both 3 inches. It is important to note that this flange will only fit in a 3-inch pipe.

3. The 3 and 4-Inch Flange

This toilet flange is designed in such a way that it fits inside a 4-inch drainpipe or over a 3-inch drainpipe. This means that if you have a 4-inch pipe, the flange will be inserted in the pipe while if you have a 3-inch pipe, the pipe will be inserted in the flange.

Toilet Flange Height

As mentioned, the toilet flange should be at most ¼ inch above the bathroom floor. What do you do when the toilet flange is too high?

With a toilet flange that is too high, you normally have 2 options. You either lower the flange or raise the floor. Raising the floor is much more expensive, but lowering the flange means cutting the flange, which has its own risks that might even cost more expensive repairs.

If the flange is glued into the drainpipe, it will involve chiseling the flange out. The danger is that you can damage the drainpipe, which means installing a new one.

Offset Toilet Flange

Offset toilet flanges are flanges that are installed in a drainpipe with a non-standard rough-in to install standard toilets.

Standard toilets have a rough-in of 12 inches, while non-standard toilets have a rough if of 10 or 14 inches. The rough-in is the distance between the rear finished wall and the center of the drainpipe.

If you have an old 10 or 14-inch rough-in toilet that you need to replace with a modern one, it is always hard to get another of the same dimensions, and if you do, it is grossly overpriced.

To solve that problem, you should install an offset toilet and buy your favorite standard toilet.

How Do You Remove a Glued-in Toilet Flange?

PVC flange pipes are normally glued inside the toilet drainpipe and secured on the floor using screws. So how do you remove a glued-in flange?

  • Remove the flange screws with a screwdriver.
  • Cut off the top part of the flange and flush off the floor using a reciprocating saw. The sleeve of the flange will now be left glued to the pipe.
  • Plug off the drainpipe below the sleeve with a rag to prevent anything from falling down.
  • Use the saw to make vertical cuts along the length of the flange sleeve, being careful not to cut the drainpipe.
  • Use a wood chisel and a hammer to remove the several cut sections of the flange sleeve.
  • Smooth the inside of the drainpipe with an emery cloth.
  • Remove the rag