A toilet flange should sit flush with the finished floor or up to 1/4 inch above it, highlights Bigham & Associates professionals. When a new floor is installed over the old one, the flange ends up recessed below the new floor surface. The wax ring cannot bridge the gap between a recessed flange and the toilet. Water leaks past the ring, the subfloor rots, and the toilet rocks on the high floor with nothing supporting it at the flange. A flange extender raises the flange to the correct height without cutting out the old flange and replacing the drain pipe.

A flange extender costs $8 to $15, installs in 10 minutes, and is the correct fix for a flange that is recessed up to 1 inch below the finished floor. If the flange is recessed more than 1 inch, stack two extenders or use a jumbo wax ring with a single extender. If the flange is cracked, broken, or the bolt slots are stripped, a flange extender will not fix those problems. The extender only raises the height. The original flange must be structurally sound. Here is how to install one correctly so the toilet seals and does not rock.

When a Flange Extender Is Needed

The toilet flange is the metal or plastic ring that sits on top of the drain pipe and is screwed to the subfloor. The toilet bolts pass through slots in the flange, and the wax ring seals between the bottom of the toilet and the top of the flange. When a new floor is installed, whether it is tile, vinyl plank, or laminate, the finished floor is higher than the original floor. The flange, which was installed flush with the original floor, is now recessed below the new floor.

A flange that is recessed below the finished floor by more than 1/4 inch cannot seal properly with a standard wax ring. The wax ring is designed to compress between the toilet and a flange that is at or above the floor surface. When the flange is recessed, the gap between the toilet and the flange is larger than the wax ring can fill. Water leaks past the ring at the first flush. A jumbo wax ring can compensate for a recess of up to 1/2 inch. A flange extender is the correct solution for any recess greater than 1/2 inch.

The EPA WaterSense program encourages proper toilet installation and maintenance to prevent leaks that waste water. A leaking wax ring from a recessed flange can waste hundreds of gallons per year through a slow, undetected seep into the subfloor.

Types of Flange Extenders

A spacer ring is a plastic or metal ring the same diameter as the flange, with bolt slots that align with the existing flange slots. It stacks on top of the existing flange and is held in place by the same screws that hold the original flange to the subfloor, or by the toilet bolts. Spacer rings are available in 1/4-inch, 1/2-inch, and 3/4-inch thicknesses. Stack two or three rings to reach the exact height needed. The rings nest together so the bolt slots remain aligned.

A wax-free flange extender kit includes a rubber gasket that presses into the existing flange and a spacer ring that bolts on top. The rubber gasket seals against the original flange. The spacer ring provides the new sealing surface at the correct height. This type is more forgiving of an irregular or damaged original flange surface than a simple spacer ring and is the better choice when the original flange is old, pitted, or has an uneven surface.

Installation Steps

Remove the toilet. The toilet must be lifted off the flange. A flange extender cannot be installed with the toilet in place. Turn off the water, disconnect the supply line, remove the flange bolt nuts, rock the toilet to break the wax seal, and lift the toilet straight up. Set the toilet aside on a drop cloth. Scrape the old wax off the flange and the bottom of the toilet.

Measure the recess depth. Place a straightedge across the finished floor on both sides of the flange. Measure the distance from the bottom of the straightedge to the top of the flange. This is the recess depth. The extender should bring the flange to flush with the finished floor or up to 1/4 inch above it. Select the extender thickness or combination of rings that matches the recess depth.

Clean the flange surface. The extender gasket or the spacer ring must seal against a clean, smooth surface. Remove any old wax, caulk, rust, or debris. If the original flange is cast iron and heavily rusted, wire-brush the sealing surface. A rusted surface that is pitted can still seal against a rubber-gasketed extender kit. It will not seal against a simple spacer ring.

Install the extender. For a spacer ring type, place the first ring on top of the flange with the bolt slots aligned. If stacking multiple rings, nest the second ring into the first. The bolt slots on all rings must align. The toilet bolts pass through all the rings and the original flange. For a wax-free kit type, press the rubber gasket into the original flange opening. The gasket should fit snugly. Place the spacer ring on top of the gasket and align the bolt slots.

Insert the toilet bolts into the bolt slots in the extender and the original flange. The bolts must pass through all layers. If the bolts are too short because the flange is now higher, replace them with longer bolts. Toilet bolts are available in lengths from 1-1/2 to 3 inches. The bolt should extend at least 1/2 inch above the toilet base after the toilet is set, to allow the nut, washer, and cap to be installed. A bolt that is too short cannot be extended. It must be replaced.

Install a new wax ring on the extender. The wax ring sits on the extender, not on the original flange. The extender is now the sealing surface. Do not stack two wax rings on top of an extender. The extender already compensates for the height difference. One standard wax ring is sufficient. Set the toilet on the extender by lowering it straight down onto the bolts. Press down firmly to compress the wax ring. Tighten the flange bolt nuts alternately until the toilet is snug and does not rock. Connect the supply line. Turn the water on and test for leaks.

Common Mistakes

Using a flange extender on a cracked or broken flange. The extender relies on the original flange for structural support. If the original flange is cracked at the bolt slots, the bolts will pull through the crack when the toilet is tightened. Replace the flange or install a flange repair ring before adding the extender.

Stacking too many extenders. Each extender ring moves the toilet farther from the original flange, which increases the leverage on the bolts and the original flange. If the flange is recessed more than 1 inch, the extender stack is too tall and the toilet will be unstable. The correct fix for a flange recessed more than 1 inch is to remove the old flange and install a new one at the correct height, or to install a flange repair ring with an integrated riser that bolts to the subfloor independently of the original flange.

Forgetting to align the bolt slots. A spacer ring installed with the bolt slots rotated 90 degrees from the original flange slots blocks the bolt path. The bolts cannot be inserted. Check the alignment before securing the extender. All bolt slots on all rings must form a continuous path from the extender surface down to the original flange.

Using the old wax ring. A wax ring is a single-use product. Once compressed, it does not rebound. Removing the toilet to install a flange extender destroys the old wax ring. Install a new wax ring when resetting the toilet. The wax ring costs $5. The water damage from a reused wax ring that leaks costs hundreds or thousands.

Frequently Asked Questions

Is a flange extender better than a jumbo wax ring?

For a recess of 1/2 inch or less, a jumbo wax ring is sufficient and simpler because the toilet does not need to be modified. For a recess greater than 1/2 inch, a flange extender is the correct fix. A jumbo wax ring compressed more than 3/4 inch can extrude into the drain pipe and cause a clog. A flange extender raises the sealing surface so a standard wax ring can be used at the correct compression height. The extender is the more technically correct solution for any recess that exceeds the capacity of a single wax ring.

I installed tile over the old floor. The flange is now recessed by 3/4 inch. How many extenders do I need?

A single 1/2-inch extender plus a standard wax ring, or a 3/4-inch extender, depending on the exact measurement. Measure from the top of the finished tile to the top of the flange. The extender should bring the flange surface to flush with the tile or up to 1/4 inch above. If the flange is 3/4 inch below the tile, a 3/4-inch extender brings it to flush. A 1/2-inch extender leaves the flange 1/4 inch below the tile, which is within the acceptable range for a standard wax ring.

Can I use a flange extender on a PVC flange?

Yes. Flange extenders work on PVC, cast iron, and ABS flanges. The extender does not bond chemically to the flange. It is a mechanical spacer held in place by the toilet bolts and the weight of the toilet. The material of the original flange does not matter as long as the flange is structurally sound. A PVC flange with a broken bolt slot cannot be extended because there is nothing for the bolt to anchor to. A PVC flange that is intact can be extended just like a cast iron flange.

Last modified: July 16, 2026