How to Install a Toilet Flange Extender

When to use a flange extender

A toilet flange (also called a closet flange) is the fitting that connects the toilet to the drain pipe and anchors the toilet to the floor with bolts. The top of the flange should sit at or slightly above the finished floor level. If the flange sits below the floor, the wax ring may not compress enough to seal, and the toilet can rock, leak, or allow sewer gas to escape.

A flange extender, sometimes called a spacer ring, is a plastic or PVC ring that sits on top of the existing flange to raise its height. Use one when the flange top is below the floor by more than a thick wax ring can compensate. If the flange is only slightly low, within the range of a thick wax ring, you can skip the extender. If the flange is below the floor by roughly a quarter inch or more, an extender is the more reliable fix.

Assess the gap before buying anything. Place a straightedge across the floor over the flange and measure from the bottom of the straightedge to the top of the flange. That measurement tells you how much height you need to add. Most extenders add a small increment, and some kits include multiple rings so you can stack them if the gap is larger, though stacking more than two is rarely a good idea.

An extender is not the right tool for every situation. If the flange is cracked or broken, replace the flange first. If the drain pipe is recessed far below the floor, the problem may be a flange that was installed too low when the pipe was set; an extender can fix the height, but a cracked pipe or a flange that does not align with the drain opening needs a different repair. For a thorough explanation of flange construction and materials, see our article on toilet flange basics.

Note that if the toilet is being installed for a commercial or public facility, the Americans with Disabilities Act (ADA) Standards for Accessible Design set minimum requirements for newly constructed and altered facilities. Those standards cover toilet height and clear floor space, not the flange, but if you are working on such a facility, review the applicable requirements before starting. The 2010 ADA Standards are the current version adopted by the Department of Justice.

Tools and materials

You will need the following items for the job:

A flange extender kit that matches your flange and drain pipe size

A new wax ring (or a wax-free gasket if you prefer)

A putty knife or scraper for old wax residue

An adjustable wrench or socket set for the flange bolts

A screwdriver or drill for the extender screws

A utility knife if trimming is needed

Shop rags for cleanup

• Flange extenders are typically made of plastic or PVC and come in round or oval shapes. Match the shape to your toilet base and the size to your drain pipe.
• The extender's inner diameter must be at least as large as the drain pipe opening. If the extender reduces the opening, it can restrict waste flow and lead to clogs.
• If the existing flange sits below the floor, the extender must raise it to roughly floor level or slightly above. Check the finished height with a straightedge after installation.

Step-by-step installation

Follow these steps in order:

Start by removing the toilet. Shut off the water supply at the shut-off valve, flush to empty the tank and bowl, then disconnect the supply line. Remove the nuts from the flange bolts and lift the toilet straight up. Set it on a surface where it will not tip or break.

Clean the old wax ring residue from the flange and the floor. Scrape carefully so you do not gouge the flange or the subfloor. Remove the old flange bolts if they are corroded or stripped; you will likely need new ones.

Insert the flange bolt heads into the slots on the existing flange. If the slots are blocked or the flange is set too low to hold the bolts, the extender kit may include replacement bolts that thread into the extender itself.

Place the extender over the flange. It should fit snugly around the flange or sit on top of it, depending on the brand. Align the extender's bolt slots with the existing slots, and align the center hole with the drain pipe. If the extender has a tapered inner lip, make sure it does not protrude into the drain opening.

Drive the screws that came with the kit through the extender's screw holes into the underlying flange or subfloor. Do not overtighten. The goal is to hold the extender firmly without cracking it. If the extender has multiple layers, secure each one in turn.

Check that the top of the extender is level with or slightly above the finished floor. Use a straightedge to confirm. If it is still below the floor, add another extender layer if the kit supports stacking, or consider a different approach.

Set a new wax ring on top of the extender (or place a wax-free gasket). The wax ring should sit centered over the opening. Then lower the toilet into position, aligning the flange bolts with the holes in the toilet base. Press down gently to seat the toilet, then tighten the nuts in a crisscross pattern. Do not overtighten, as the porcelain can crack.

Reconnect the supply line, turn on the water, and flush several times. Check for leaks at the base and at the supply connection. If the toilet rocks or water seeps out, you may need to reset it with a fresh wax ring.

Flange too low versus flange too high

A flange that sits below the floor is the condition an extender fixes. A flange that sits well above the floor is a different problem. If the flange is proud of the floor by more than a quarter inch or so, the toilet may not sit level, and a standard wax ring might not seal around the high flange. In that case, the flange itself may need to be adjusted or replaced. Our separate article on how to fix a toilet flange that is too high covers that scenario.

For a slightly low flange, a thick wax ring can often do the job. A standard wax ring without a funnel is about an inch thick, and thick rings add roughly a quarter inch of extra height. If the flange is only slightly recessed, a thick ring is the simpler solution. If the gap is larger, an extender is the more dependable choice because it provides a solid, rigid surface for the wax ring to compress against.

Do not try to compensate for a very low flange by stacking multiple wax rings. Stacked wax rings can squeeze out unevenly and are more likely to leak than a properly raised flange. The extender is the right tool for that job.

Alternatives and related situations

If the flange is recessed because the finished floor was raised, for example after adding a second layer of tile, the extender is a quick fix that avoids removing the flooring. If the floor was raised significantly, you may need an extender that adds enough height to reach the new floor level. Some kits come with a taller extender that acts as a riser.

If the existing flange is made of cast iron, the screw holes for the extender may not accept self-tapping screws. In that case, use a kit that includes screws designed for metal, or drill pilot holes. If the cast iron flange is corroded or cracked, replacement is the safer route. For guidance on removing and replacing the flange itself, see how to replace a toilet flange.

When the flange is below the floor but the toilet base is already tiled, the extender should be installed from above. If you are installing a toilet on a new tile floor that has not been laid yet, the better approach is to set the flange at the correct height before tiling. In a retrofit, the extender is the standard remedy.

If you are removing the toilet entirely for a remodel, plan for the flange height during the rough-in stage. The flange should sit so its top is at or slightly above the finished floor. Checking that height before you set the toilet avoids the need for an extender later. For more on the process of removing a toilet, see our how to remove a toilet article.

A floor that is uneven or has gaps around the flange can also create problems. An extender will not fix a wobbly subfloor. If the floor flexes under the toilet, the wax ring can break its seal over time. Address the floor structure before installing the extender.

Installation tips and common mistakes

Read the instructions that come with your extender kit before starting. Kits vary in how they attach: some use screws into the existing flange, others use adhesive or a compression fit. Follow the manufacturer's method.

A common mistake is leaving the old flange bolts in place when they are too short to reach through the extender. Check bolt length after adding the extender. The bolts must pass through the toilet base far enough to thread the nuts. If they are short, replace them with longer bolts from the kit or from a hardware store.

Another mistake is using an extender whose inner diameter is smaller than the drain pipe. That creates a ledge where waste can catch and cause clogs. Verify the size before buying and before installing.

Do not use silicone caulk or construction adhesive in place of the screws provided in the kit. The screws hold the extender firmly to the flange. Adhesive alone can allow the extender to shift when you lower the toilet.

If the toilet rocks after installation, check that the flange bolts are tightened evenly, but do not rely solely on the bolts to pull the toilet down. A toilet that rocks when you press on it usually means the wax ring is not fully compressed or the flange is still too low. Remove the toilet, check the extender height, and reset it with a new wax ring if needed.

If you are not sure whether the gap is small enough for a thick wax ring, measure it. If the flange top sits less than about a quarter inch below the floor, a thick wax ring should work. If the gap is larger or the flange is uneven, use the extender.

After installation, run water for several flushes and inspect the joint at the floor. Any water on the floor is a sign that the seal is not complete. Minor adjustments are easier to make right away than after the toilet has been in use for days.

For a full guide to setting the toilet on a new flange or resetting one, see how to install a toilet. If you are working on a tile floor, our article on installing a toilet on tile has specific advice.

What to pick for your situation

When choosing a flange extender, the key factors are the gap you need to bridge, the material of the existing flange, and the size of your drain pipe. If the flange is only slightly low, a thick wax ring may be enough. If the flange is recessed by more than that, an extender is the right product. Buy a kit that includes screws and bolts, and check that the inner diameter matches your pipe.

What to pick for your situation

Questions

How do I know if my toilet flange is too low?

Set a straightedge across the floor over the flange. If the top of the flange is below the floor surface, it is low. Many flanges sit slightly proud of the floor, which is ideal. If the difference is more than a thick wax ring can handle, roughly a quarter inch or more, use an extender.

Can I stack two flange extenders?

Some extender kits are designed to stack, and the rings are sold in a way that allows adding one on top of another. Stacking more than two layers increases the risk of instability and leaks. If the gap is large, consider addressing the flange height at the pipe level instead of stacking spacers.

What is the difference between a flange extender and a thick wax ring?

A thick wax ring provides extra vertical allowance for the wax to compress around the flange. A flange extender physically raises the flange itself. A thick ring is fine for small gaps. An extender is better for larger gaps because it provides a flat, rigid surface for the wax ring to seal against.

Will a flange extender reduce the drain opening?

It can if the inner diameter is too small. Check the extender's inner diameter against the drain pipe opening. The extender should be at least as large as the pipe to avoid a ledge that can catch waste.

Do I need a new wax ring when I install an extender?

Yes. Reuse of an old wax ring will likely fail because it has already been compressed and may be brittle. Install a fresh wax ring (or a wax-free gasket) on top of the extender before setting the toilet.

What if the flange is still low after adding one extender?

If the extender kit allows stacking, add a second ring and recheck the height. If the gap is still too large, the better fix is to correct the flange at the pipe level or replace the flange assembly with one that positions the ring at the correct height.