A Fantastic 3.5-Inch Toilet Flange Replacement Guide

A loose or improperly installed toilet flange can cause toilet leakage from the bottom. This leak results in water damage, unwanted wastewater, and sewer gas on your floor.

That is why it is crucial to fix the issue as soon as possible.

Sometimes, you can repair 3.5-inch toilet flanges rather than replace them. Carefully inspect your toilet to see the severity of the damage.

Unsure of what to do? That is why we have compiled a guide on replacing a broken toilet flange if you experience such an issue.

Toilet Flange Sizes

You can only install a 3.5-inch toilet flange on a 3.5-inch bend or 3.5-inch drain pipe.

In contrast, 4-inch drain pipes are capable of carrying more waste. These pipes are for when many toilets connect to the same pipe. But, if your exhaust pipe is 4 inches instead of 3.5, you will need a 4×4-inch flange.

Double-check your pipe’s size to ensure you get the correct flange.

Beware, using the wrong size flange can affect the alignment of the piping. If your flange has incorrect dimensions, it can cause leaks during use. You do not want to have to start all over again.

Toilet Flange Replacement

If you notice water leaking from your toilet after flushing, this implies a broken flange. Time to replace it!

Below is a short guide on replacing your broken toilet flange. 

Before You Do Anything

Before replacing a damaged flange, research flange materials and sizes for a good fit. 

If you notice a lot of water accumulating at the toilet base, give it some further inspection. There may be an issue with caulking at the toilet base, which is an easy issue to fix.

Or, you may find a cracked or broken flange, which means it is time to replace it

We recommend checking the area around the toilet for any flange issues once in a while.

Here are some other areas to check that may be impacting your flange and its future replacement.

Check the Wax Ring

If water leaks from the bottom after flushing, lift the toilet. After lifting the toilet, check the bottom to see if the wax ring is correct and if the flange is loose.

A flange seals to the toilet drain with the help of a wax ring to prevent leaks. Wax rings are gaskets between the flange and the toilet to help prevent leaks.

Wax rings come in many sizes, so keep this in mind when shopping around. If the floor uses denser material, use a thicker wax ring to prevent leaks.

If you are unsure of the issue, try putting a new wax ring on your 3.5-inch toilet flange and return it to the drain pipe.

Ensure Sizes Are Compatible

If you are not sure about the size of your bathroom pipe, be sure to double-check before proceeding. The correct flange size depends to some extent on the size of your toilet and piping.

Toilet flanges are usually available in standard 4×3 inch sizes. They should also be 3 or 4 inches in diameter, depending on the size of the drain pipe. The bottom of the flange is only 3 inches as its design connects to a standard size 40 pipe.

The base of the offset toilet flange usually fits in a 3-inch PVC pipe or inside a 4-inch pipe.

As you can see, the offset toilet flange is mostly PVC. There is a rotatable metal or PVC flange ring surrounding the top to center the bolts under the toilet. All floor flanges use solid ABS material and will fit two or four-bolt toilets.

When replacing a round toilet with an elongated toilet, buy staggered toilet flanges. These flanges have diagonal openings and extra space to accommodate the elongated bottom.

Shop at your local home improvement store or online and you will find a device called an offset toilet flange. You’ll also want a pipe that can be connected to the new offset flange.

If necessary, you can use a toilet flange extension or cut your piping to ensure the correct flange height. Using a jigsaw, cut out where the offset flange should be. Ensure you position it further away from the wall.

The flange also directs a 4-inch toilet drain into a 3-inch hole in the black tank. To seal a modern toilet, it must have a flange approximately ⅜-inch thick resting on the flooring. 

The flange is usually made of PVC, copper, steel, or brass material. The flange then connects to metal or plastic rings, securing the flange to the bathroom floor.

Toilet Flange Pre-Installation

This next step is easier to do with a partner since the toilet often obscures the view of the new mounting bolts. The flange connects the toilet drain to the domestic plumbing. So, we will need to focus on the two holes between the flush knob and your home’s drainage system.

The cabinet flange is the mechanical connection between these two holes. You will use a flange to connect the toilet drain to the pipes in your home. You want to ensure the model you choose can connect your bathroom to your home’s piping system. 

Double-check that you know where all the toilet’s components are and the material sizes you will need.

Toilet Flange Installation

The next step is to remove and replace the existing flange.

Here are the materials you will need:

  • Wooden or cement screws and bolt caps
  • An electric drill (hammer drill if drilling into concrete) and a screwdriver
  • Pre-measured gasket, flange, wax ring, and pipe
  • Washers, nuts, and bolts or an optional kit

When the subfloor is concrete, as in basement bathrooms, replacing the flange is not easy.  Drilling holes in the concrete to attach the new flange can be difficult.

If you have a concrete subfloor, we recommend calling a plumber to check your flanges after installation.

If you cannot install the toilet flange on a bare floor, you can use a gasket that fits over the existing flange. 

Secure your floor trim flanges to your floor slab using the provided installation hardware from your kit, if you bought one. 

If the hardware is not provided, use wooden or cement screws, depending on the subfloor material. Slide your toilet’s flush bolts onto your new flush. Secure them using the washers and nuts.

Next, install the new wax rings which will match the new flange. The thickness of your floor will determine how thick you need your wax rings to be. If you installed a thicker tile after installing your initial toilet, use a thicker wax ring.

Applying Sealant After Installation 

After we have replaced our toilet flange, it is necessary that we also cover it up with some sort of sealant. For this, we recommend Ferncos wax-free toilet sealant.

Ferncos wax-free toilet sealant uses a flexible PVC material. This material uses adhesives and barbed fittings (instead of gaskets) to create a positive seal on the spigot and drain pipe.

Or, you can choose a different type of flange material or form. Not only can you customize PVC plastic for almost any gutter configuration, but it is also affordable.

Wrapping Up

Toilet flanges do not make it easy when it comes to replacing a damaged one. Determining the right size and model can be research-heavy. Installation can be just as confusing. 

But, hopefully, this short guide has shown you a thing or two about replacing your 3.5-inch toilet flange.

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