How to Cut Plastic Toilet Shims – Step by Step Guide

A rocking or wobbly toilet bowl is a surprisingly common problem. The problem can develop because the underside of the toilet is not resting flat against the floor, which is often due to the components which connect it to the drain pipe. The result is that the toilet becomes uneven, wobbly, and a real annoyance.

In this article, we’re showing you a simple way to level a rocking toilet – by installing plastic toilet shims, sometimes called wobble wedges.

new ceramic toilet bowl near grey wall

Leveling a toilet might sound like a difficult job, but it’s quite simple. In any case, the solution starts by identifying the problem. You’ll need to check the bolts surrounding your toilet to see if any have come loose. If your toilet is still loose, cut and install shims to even the base, and apply caulk to keep it that way. Below, we’ll show you exactly how to do it and how you can install a plastic shim or two to level your toilet.

Related: How to remove an object from your toilet trap.

Step-By-Step: How do you stop a toilet from rocking?

Before Your Begin: Gather Your Materials

Step 1: Check the Bolts on the Toilet

Fixing a rocking toilet might be easier than you think. The first step is to check the bolts on the toilet that secure it to the ground. There should be two bolts, both located toward the backside of the toilet. Use a wrench, and secure each toilet bolt slowly. Don’t tighten too hard or too fast because you can risk cracking the porcelain. Tighten to the point where the toilet is snug against the ground.

NOTE – Check for Leaks: While you’re checking out the loose toilet base, see if there is water surrounding the base. If this is the case, the toilet wax ring or wax seal that secures the toilet to the ground may be damaged, and you will have to remove the toilet and perform a more extensive repair (or call a plumber).

If this doesn’t fix the problem, and there is no leakage. Move on to the next step.

Related: Replacing a toilet seat with hidden bolts.

Step 2: Find the Source of the Problem

If the bolts weren’t the issue, find the source of the unbalance. Check around the base of the old toilet supply line and look for any gaps where the toilet raises from the floor. It can help to sit on the toilet or move it around to see which direction it will tilt. Be sure to test in all directions, including the back of the toilet.

If you find any gaps, move on to the next step.

Step 3: How Do You Use Plastic Shims? Can you use shims to level a toilet?

It’s time to use your plastic shims. Using shims is a trial and error process. You’ll need to insert them into the gaps, pushing them in slowly until you fill the gap. Your aim is to insert the shims around the base so the toilet no longer rocks. Be sure to check that the toilet doesn’t rock in any direction. Gently push the toilet in each direction to make sure it is stable.

Step 4: Cut Shims Around the Toilet – How do you cut around a toilet?

Once the shims are securely in place and you are sure your toilet is stable, you should add an initial layer of silicone caulk underneath the hard plastic shims. Let it dry overnight so your shims are securely in place.

Once dry, take your utility knife, and cut through the shims where they meet the toilet. Be careful you don’t slice into the toilet or your floor!

Step 5: Caulk the Base

Place a layer of caulk around the base of your toilet to eliminate the gap between the toilet and the floor. It also hides your shims from view. It will add a final, professional touch to your work.

Be sure to buy suitable caulk – it will probably be called tub & tile or something similar. Take the caulking gun, and apply a layer of caulk underneath the toilet, being sure to cover the entire gap between the floor. Wipe the caulk flat against the toilet for a professional appearance.

Don’t forget to leave a small area uncaulked near the back of the toilet, so you can spot any leaks should they occur.

Let the caulk dry overnight, and you’re good to go!

toilet bowl in modern bathroom interior

Frequently Asked Questions

Are There Any Other Reasons My Toilet Might Rock?

Yes! But unfortunately, it will be a difficult solution. Your toilet attaches to the plumbing with a toilet flange bolt supported by a ring bolted to the toilet base. This is the area where your toilet drains into the plumbing.

Needless to say, if there are issues with the closet flange ring or with the closet bolts which attach to the ring, your toilet can become loose and start to rock.

This is a more significant fix, which requires removing the toilet itself. Luckily, this is still an achievable task without calling a plumber. Most of the time, you will need to remove the toilet tank and toilet seat and attach a new toilet flange ring (available at your local hardware store).

How do I know if my toilet is leaking from underneath?

As mentioned near the start of our guide, one of the more significant issues which can occur at the base of a wobbling toilet is leakage.

This leakage is often caused by a weakened flange ring, similar to what was mentioned directly above. If your toilet is not properly draining directly into the flange, through the flange ring, then it might leak out the sides.

You may also have a problem with the flapper, the valve that drains water from the tank into the bowl. Once again, the solution will be to remove the toilet and replace these components.

How do you make long shims?

You can order custom-made long shims or cut them yourself using a larger piece of plastic and a jigsaw. Wood shims are also an option.

modern white plain clean toilet bathroom with shower tiles


Thanks for checking out our guide to fixing a wobbly toilet! As you can see, the job is straightforward once you know what to do. Be sure to keep keen attention to detail and extensively test your toilet for wobbles before caulking it shut. We’re confident you can fix the issue and protect your finished floor without even thinking about calling a plumber!

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