How to Install a Toilet Flange Extender
Updated February 25, 2026
Raise a toilet flange that sits below the finished floor -- fix rocking toilets and wax ring leaks caused by new tile or flooring installed over the original subfloor.
Overview
When you install new tile, hardwood, or LVP over the original subfloor, the floor gets higher but the flange stays where it was. Now the flange sits below the finished floor -- sometimes 1/4 inch, sometimes a full inch. A standard wax ring cannot bridge that gap reliably. The toilet rocks, the wax seal fails, and you get sewer gas or water leaking at the base. A flange extender raises the flange back to floor level. It is a plastic or metal ring that stacks on top of the existing flange. $5-$20 and 30 minutes.
What You'll Need
Safety First
- Stuff a rag into the drain pipe after removing the toilet to block sewer gas. The open drain pipe vents directly from the sewer system.
- Do not stack multiple wax rings as a substitute for a flange extender. Double-stacked wax rings are unstable and prone to shifting -- use the extender to bring the flange up, then a single wax ring on top.
Step-by-Step Instructions
- Remove the Toilet
Shut off the supply valve. Flush and sponge out remaining water. Disconnect the supply line. Remove the closet bolt nuts. Rock the toilet gently to break the old wax seal, then lift straight up. Set on cardboard or a towel. Stuff a rag in the drain opening. Scrape all old wax off the flange and the floor around it with a putty knife.
Tip: Take a photo of the flange before cleaning it. This helps when buying the right extender size -- you can show the photo to the hardware store associate. - Measure the Gap
Place a straightedge (a level or ruler) across the flange opening, resting on the finished floor on each side. Measure the gap between the bottom of the straightedge and the top of the flange. That is how far below the floor your flange sits. Extenders come in different thicknesses: 1/4 inch, 1/2 inch, 3/4 inch, and adjustable stacking rings. Buy the thickness that brings the flange flush with the floor surface or up to 1/4 inch above it.
Tip: The flange should end up flush with the finished floor or up to 1/4 inch above it. Above floor level is slightly better -- the wax ring compresses against the flange more reliably. Below floor level, even by 1/4 inch, makes the wax seal marginal. - Install the Extender
Clean the top of the existing flange -- it needs to be flat and free of old wax. Apply a bead of silicone sealant around the top edge of the existing flange. Set the extender ring on top, aligning the bolt slots. Press down firmly. Some extenders screw into the existing flange with the included stainless steel screws. Others use the closet bolts to hold everything together. If the extender has screw holes, drill pilot holes and drive the screws. Let the silicone set for 15 minutes.
Tip: The Oatey Set-Rite flange extender ($10-$15) is adjustable -- it comes with stackable rings in 1/4-inch increments that let you dial in the exact height. No guessing, no returning the wrong size. - Set the Wax Ring and Reinstall the Toilet
Insert new closet bolts into the extender slots. Place a standard-thickness wax ring on the extender, centered over the drain. Lift the toilet, align the base holes over the bolts, and press straight down. Do not twist or rock. Hand-thread the washers and nuts. Alternate sides, tightening a few turns each. Snug plus a quarter turn -- stop when the toilet does not rock. Level check. Shim if needed. Caulk the base with a gap at the back.
Tip: With the flange now at the correct height, a standard wax ring is all you need. Do not use an extra-thick wax ring on top of an extender -- the extra wax can squeeze into the drain pipe and restrict flow.
Pro Tips
- If you are installing new flooring, plan for the flange. Cut the flooring around the flange and install the extender before setting the toilet. Much easier than doing it after the fact.
- PVC flange extenders work on PVC, ABS, and cast iron flanges. They are universal. The extender sits on top -- it does not connect to the drain pipe material directly.
- A wax-free gasket (Fluidmaster Better Than Wax, $10-$15) works well with flange extenders because it compensates for slight height variations and allows repositioning without replacement.
- If the existing flange is cracked or broken in addition to being low, use a repair flange (Oatey 43539 or similar) that bolts on top of the old one and adds height at the same time. Two problems, one fix.
- Stacking flange extenders more than 1 inch total is not recommended. If the gap is more than 1 inch, the existing flange may need to be replaced at a higher position -- that is a plumber job involving drain pipe work.
When to Call a Pro
Call a plumber if the flange is more than 1 inch below the finished floor (requires replacing the flange at the correct height, which involves cutting the drain pipe), if the existing flange is severely corroded cast iron that cannot hold screws, or if the subfloor around the flange is water-damaged and soft (needs subfloor repair before the flange work).
Frequently Asked Questions
When should I call a plumber to install a toilet flange extender?
Call a plumber if the flange is more than 1 inch below the finished floor (requires replacing the flange at the correct height, which involves cutting the drain pipe), if the existing flange is severely corroded cast iron that cannot hold screws, or if the subfloor around the flange is water-damaged and soft (needs subfloor repair before the flange work).
What are some expert tips to install a toilet flange extender?
If you are installing new flooring, plan for the flange. Cut the flooring around the flange and install the extender before setting the toilet. Much easier than doing it after the fact. PVC flange extenders work on PVC, ABS, and cast iron flanges. They are universal. The extender sits on top -- it does not connect to the drain pipe material directly. A wax-free gasket (Fluidmaster Better Than Wax, $10-$15) works well with flange extenders because it compensates for slight height variations and allows repositioning without replacement. If the existing flange is cracked or broken in addition to being low, use a repair flange (Oatey 43539 or similar) that bolts on top of the old one and adds height at the same time. Two problems, one fix. Stacking flange extenders more than 1 inch total is not recommended. If the gap is more than 1 inch, the existing flange may need to be replaced at a higher position -- that is a plumber job involving drain pipe work.
What tools do I need to install a toilet flange extender?
You will need: Flange extender kit ($5-$20, matched to the gap measurement), Putty knife (for scraping old wax), Silicone sealant (to seal between the extender and existing flange), Screwdriver or drill (for extender mounting screws), Adjustable wrench (for closet bolt nuts), Level (to check the toilet is sitting flat), New wax ring or wax-free gasket.
When should I call a professional instead of doing this myself?
Call a plumber if the flange is more than 1 inch below the finished floor (requires replacing the flange at the correct height, which involves cutting the drain pipe), if the existing flange is severely corroded cast iron that cannot hold screws, or if the subfloor around the flange is water-damaged and soft (needs subfloor repair before the flange work).
How difficult is this project?
This project is rated easy. Most homeowners with basic tools can complete it.
How long does this take?
Plan for approximately 30 - 60 minutes. First-timers may need extra time.
How much will this cost?
The estimated cost is $5 - $20. Costs vary by location and materials chosen.