How to Fix a Loose or Rocking Toilet

A loose or rocking toilet is a common problem that can cause frustration and lead to potential leaks or damage if not addressed. Luckily, fixing a loose toilet is usually a straightforward DIY project that can be done in under an hour with some basic tools and supplies.

In this comprehensive guide, we will cover the causes of a loose toilet, the steps to diagnose the specific problem, and how to fix a loose toilet using a variety of effective methods. With some helpful tips and precautions, you can level your toilet, stabilize it, and eliminate that annoying wobble for good.

What Causes a Loose Toilet?

There are a few main reasons why your toilet may become loose and rock back and forth or side to side when you sit down on it:

Improper Installation

The most common cause of a loose toilet is that it was installed improperly. The toilet needs to be set down firmly and evenly on the flange and secured in place using bolts through the base. If the bolts are loose, the nuts are not tightened properly, or if the flange itself is not affixed flat to the floor, it can result in a loose connection.

Worn Toilet Flange

The toilet flange is a metal or plastic fitting that is screwed into the drain opening beneath your toilet. Over time, the flange can crack, deteriorate or bend, leading to a loose and unstable toilet. A worn flange cannot properly hold the bolts that secure the toilet, causing rocking.

Broken Seal

There is a wax seal that sits between the bottom of the toilet and the flange to create a watertight connection. If this seal breaks or leaks for any reason, it can erode the stability of the toilet. Water exposure under the toilet will rot the subfloor, making bolts loose and causing wiggle.

Warped Subfloor

The floor surface around the flange beneath the toilet needs to be flat and level. If the plywood or concrete subfloor becomes uneven, warped, or damaged over time, a good seal is not possible. Gaps and inconsistencies under the toilet can lead to looseness.

Loose Mounting Bolts

And finally, the two bolts that go through the base of the toilet on either side and attach to the floor flange may become loose over time due to debris, corrosion, movement, etc. This can immediately result in a loose toilet and needs to be addressed.

How to Diagnose the Cause

When you notice your toilet rocking or loose, the first step is to diagnose the specific cause so that you can select the proper repair method.

Here are ways to inspect the toilet and determine why it is loose:

Check if you can wiggle or rock the toilet at all by applying slight pressure near the base. Try alternating sides to detect motion.
Look at the floor around the toilet base for any gap between the floor and toilet, which would indicate a damaged flange or subfloor.
Shine a flashlight at the base of the toilet and look for evidence of leakage, erosion, or backflow of waste. This points to a bad seal.
Grab the toilet at the base and lift slightly. If the toilet lifts without resistance, the bolts are loose.
Jiggle the toilet bolts with your fingers to detect any looseness. The bolts should be snug when tight.
Remove the toilet tank and sit on the bowl to diagnose rocking. If the tank is firm but the bowl rocks, it indicates floor or flange issues.
Check the floor flange for any cracks, warping, or other damage, which would make it unable to stabilize the toilet.

Doing these quick inspections should help you identify why your toilet is loose and guide your repair approach.

How to Fix a Loose Toilet

Once you determine the cause of the loose toilet, you can move ahead with the proper repair:

Tightening Toilet Bolts

If the toilet bolts are loose, the easiest solution is to tighten them up. You will need a wrench to turn the nuts on either side until very snug. Be careful not to overtighten or you can crack the porcelain base.

This may stabilize your toilet for some time, but keep in mind that loose bolts are often a symptom of a bigger underlying problem, especially a broken flange or seal.

Replacing Toilet Flange

If the metal or plastic flange is cracked, badly corroded, or broken, you will need to replace it:

Turn off water supply to the toilet. Flush to empty tank. Sponge remaining water out of tank and bowl.
Disconnect and remove supply line. Remove the nuts/bolts and lift toilet off flange. Place on cardboard to protect floor.
Use a screwdriver to remove old flange screws. Clean away old wax.
Apply plumber’s putty to rim of new flange. Press into place on floor. The flange should be stable and level.
Secure flange tightly using provided screws.
Set toilet back over flange, insert bolts, and tighten nuts.
Reconnect water supply. Turn on water and test for leaks.

Replacing a corroded or broken flange will eliminate looseness caused by a faulty flange.

Replacing Wax Seal

If the wax ring seal has failed, you will see water damage and likely some foul odors coming from beneath the toilet. Follow these steps:

Turn off water and empty toilet. Remove supply line and bolts to lift toilet.
Using a plastic scraper, carefully remove all the old wax from the flange and bottom of the toilet. Remove putty with a putty knife.
Apply a new wax ring around the flange (or insert new wax gasket). The ring should fully cover flange rim.
Lower toilet back onto flange, evenly pressing down to set wax ring. Insert bolts and tighten.
Turn on water and test for any leaks between toilet and floor.

Replacing this seal eliminates any instability caused by water corrosion or leaks under the toilet.

Shimming the Toilet Base

If the floor or subfloor surface is uneven, you can stabilize the toilet using shims:

Lift toilet and place shim material under the toilet base at whichever side is loose. Shims should be snug.
Lower toilet onto shims and test for rocking motion. Add more shims until toilet is stable.
Mark shim placement. Lift toilet and apply bathroom caulk to underside of shims to hold in place.
Lower toilet onto caulked shims. Let caulk dry before using toilet.

Shimming can work as a quick fix for small gaps or uneven spots in the subfloor.

Replacing Subfloor

For extensive floor damage or rotting subfloor caused by leaks, you may need to replace sections of the plywood or concrete around the flange:

Turn off water and remove toilet. Mark damaged subfloor area needing replacement.
Using a reciprocating saw, cut out the marked subfloor area 2 inches wider than flange.
Cut replacement subfloor to size of opening. Make sure top is level with existing floor.
Apply construction adhesive to bottom and edges. Set replacement into opening.
Drill pilot holes and screw replacement subfloor piece firmly into joists.
Install new wax seal, set toilet onto flange, and test for rocking.

This extensive repair creates a solid, level base to permanently stabilize your toilet.

Installing New Toilet

In some cases where the floor or flange is badly damaged, the simplest solution is to remove the existing toilet and install a brand new one:

Turn off water supply and disconnect supply line. Remove tank and bowl.
Scrape old wax ring from flange. Remove flange screws and pry up flange.
Set new stable, level flange into floor drain hole. Secure tightly to floor with screws.
Apply new wax ring to flange. Lower new toilet onto flange, evenly compressing wax ring.
Tighten toilet bolts very firmly to stabilize toilet. Do not overtighten to crack porcelain.
Reconnect supply line to fill valve. Turn on water and test for leaks.

Installing a new toilet with fresh bolts, wax, and flange eliminates any underlying issue and gives you a solid base.

Tips When Fixing a Loose Toilet

Always turn off water supply and empty toilet before lifting or removing toilet.
Be careful not to crack porcelain tank or bowl when setting down or removing toilet.
Wear gloves and eye protection – old seals and subfloor may contain mold.
Dispose of old wax rings, bolts, etc properly to prevent clogging drains.
Make sure new wax seal is proper size – don’t overlap bolts holes.
Tighten bolts evenly on both sides to avoid cracking tank or bowl.
After resetting toilet, test for leaks and check stabilization regularly.

Common Questions About Loose Toilets

Loose, rocking toilets are a common annoyance in many homes. Here are answers to some frequently asked questions:

How do I stop my toilet from rocking?

Your main options for stopping a rocking toilet include tightening the bolts, shimming under the base, replacing the flange or seal, repairing subfloor, or installing a brand new toilet if needed. Determine the cause then use the proper repair method.

Why does my toilet rock after I replaced the wax ring?

If the toilet rocked before replacing the wax ring, the issue is likely with the floor or flange instead. The new wax ring seals the area under the toilet again but does not address underlying subfloor or flange problems that allow rocking.

Should toilet flange bolts be tight or loose?

The two bolts that go through the base of the toilet into the floor flange should be very tight and snug to prevent any movement or rocking of the bowl. Loose toilet bolts indicate a problem.

How do you stabilize a rocking toilet?

To stabilize a rocking toilet:

Tighten bolts very firmly
Use shims under toilet base as needed
Replace flange if cracked or broken
Replace leaking wax ring seal
Repair or replace damaged subfloor
Install new toilet

How much does it cost to fix a rocking toilet?

A minor toilet rock can often be fixed with shims for $10-$30. Extensive subfloor repairs cost $150-$500. Complete toilet replacement runs $250-$600. Calling a plumber costs $180-$450.

When should you replace instead of re-securing a loose toilet?

If the floor or flange beneath the toilet is badly damaged, corroded or uneven, it is often better to do a complete replacement with new flange hardware and toilet. Attempting to re-secure it will likely result in continued looseness issues.

Conclusion

Fixing a loose or rocking toilet is an important repair to eliminate annoying movement and prevent potential leaks or water damage. By determining the cause, having the right tools and supplies handy, and following the proper procedures, you can securely stabilize your toilet and prevent future issues. Pay special attention to tightening bolts evenly, replacing any damaged seals or flanges, and ensuring the subfloor is solid. With patience and care, you can remedy a loose toilet and restore a solid, functional bathroom fixture.