How to Shim a Toilet that Wobbles or Installed Anew?

It’s happened to all of us. We go to the bathroom and find that the toilet is loose.

Maybe it wobbles a bit when we sit down, or perhaps it rocks back and forth when we try to flush it.

shim under the toilet

This can be really annoying, especially if you have to use the bathroom multiple times a day and it makes your time in the bathroom uncomfortable.

In this blog post, I will show you how to shim a toilet so that it is stable again!

How to Shim an Existing Toilet?

If your toilet is already installed and you notice that it is becoming loose, you will need to shim it.

Shimming a toilet is not difficult, but it does require a few tools and materials.

If the toilet just wobbles, follow this section. If the toilet wobbles and is leaking, follow the next section where I’ve explained the steps to shim a new toilet.

You will need:

  • A hammer
  • A screwdriver
  • An adjustable wrench
  • A putty knife
  • Shims (these can be purchased at your local hardware store)
  • Waterproof Caulk

Analyze the Wobble

The first step is to determine why your toilet is wobbling.

Is it because the floor around the toilet is uneven? Mounting bolts became loose? Caulks got out of place?

Or, is the problem with the actual toilet bowl?

Sometimes toilet bowl cracks and breaks, causing the toilet to wobble until it fails measurably.

So, the first thing to check is whether the toilet bowl is perfectly fine or not. If it’s damaged, replacing the bowl entirely is the best thing to do.

If it’s okay and the other things are to blame, then proceed to the next step in shimming your wobbly toilet.

Locate the Bolts that Hold the Toilet in Place

Once you have determined that shimming is indeed an option, you will need to locate the bolts that hold your toilet in place.

There are usually two of them and they can be found on either side of the base of your toilet.

toilet mounting nut issue

With a wrench, loosen the bolts until they are loose enough to be turned by hand.

Do not remove them completely!

Now, check if you can adjust them concurrently and stabilize the toilet without using any shim underneath.

In most cases, adjusting the bolts will solve the wobbly toilet issue. So, definitely try this out before moving forward.

If adjusting the bolts didn’t work in your favor, then proceed next.

Remove Any Old Shims

If your toilet has been shimmed before, then there is a high chance that the old shims are causing the problem.

Remove any old shims by prying them out with a putty knife or a screwdriver.

Be careful not to damage the flange or the bolts in the process. Inspect everything and make sure that there is no debris left behind before moving on.

Place New Shims as Needed

Now it’s time to place new shims under your toilet!

Start by putting one shim at each of the bolt locations. Then, check if the toilet is still wobbling.

plastic shim for toilet

If it is, add another shim in between those two until the wobble has been eliminated.

Once you have found the perfect spot for your shims, use a hammer to tap them in place.

Be careful not to push them too much as this can damage the porcelain and cause leaks.

Caulk The Base Of Your Toilet

The final step is to caulk around the base of your toilet.

This will help to further stabilize the toilet and prevent any water from leaking out.

Use a waterproof caulk for best results and follow the manufacturer’s instructions on how to apply it.

Generally, applying caulk is pretty easy with the tubes that can be applied without any caulking gun.

Apply the caulk all around the base and then finish it with a 3-in-1 caulking tool.

And that’s it. All you have to do now is wait and check a final time.

Wait and Test

Wait at least 12 hours for the caulks to cure and dry completely before using the toilet.

once the waiting is over, flush the toilet a few times and check for any leaks.

Seat on the toilet and check if it wobbles or not. Once everything is checked out, you are good to go with a perfectly stable toilet.

How to Shim a Toilet While Installing Fresh?

If you are installing a new toilet, the process is pretty much the same.

With a few slight changes, you can shim your new toilet perfectly without any issue. Here are the steps to follow-

Turn off the Water Supply

Before starting anything, make sure to turn off the water supply.

This is extremely important as you don’t want any accidents during the installation process.

Now, flush the toilet a few times until all the water has been cleared out from the bowl.

Remove the Old Toilet

Carefully remove the old toilet from its place.

Be extra careful with fragile porcelain as it can break easily. Also, don’t forget to unscrew the bolts and take out the wax ring before removing the toilet bowl.

The removal process is simple. Start with removing the toilet tank, followed by removing the bowl.

removing a toilet

There should be two mounting bolts holding the toilet. You need to make them loose and lift the toilet out carefully.

Dry fit the new Toilet Bowl

The next step is to do a dry fit of your new toilet bowl. This will help you determine whether shimming is necessary or not.

If everything looks good and there is no wobble, then you can proceed with installing it permanently.

However, if there is still a wobble, then shimming will be required before proceeding further.

Place New Shims as Needed (if required)

If shimming is required, then the next step is to place new shims as needed.

Put one shim at a time and check if the toilet stabilizes. If you get a set of shims of different heights, you should be able to fix the rocking toilet issue with a couple of shims.

Use a level to make sure that the bowl is completely level before finalizing the shimming process.

shim under the toilet

Once you are happy with the position of the shims and the toilet is level, you can proceed to the next step.

However, if you notice that changing the shim position causes the toilet to wobble during the trial process, make sure to use some markings on the floor so that you can redo the same thing again without any additional hassle.

Plastic vs Rubber Shims

There are two types of shims that you can use for this process- plastic and rubber.

Each type has its own set of pros and cons that you need to consider before making a decision.

Here is a quick comparison between the two-

Plastic Shims:

Pros- They are easy to cut and come in different sizes. You can find them in any hardware store.

Cons- They are not as strong as rubber shims and can break easily. They also tend to slip out of place more often.

Rubber Shims:

Pros- They are stronger than plastic shims and less likely to slip out of place. You can reuse them multiple times.

Cons- They are not as easy to cut and might be difficult to find in hardware stores.

Install Toilet Wax Ring & Place the Toilet

Now, install the toilet wax ring before placing the toilet in its position. Follow my guide on installing a wax ring to perfectly do this.

After placing the toilet, check if the wobble is back again. Sometimes, you’ll need to adjust a bit to get it stabilized again.

replaced toilet wax ring

Once you do that, tighten the toilet bolts until they are snug. Don’t overtighten them as it can cause the toilet bowl to crack.

Caulk The Base Of Your Toilet

Before proceeding with caulking double-check for any wobble again so that you don’t regret it after the caulk is cured.

Unless you are doing some other DIY work in your bathroom or kitchen, I recommend going with a caulking tube that doesn’t require a caulk gun for application.

caulking the toilet base

This will allow you to save money on the caulking gun and will also help you apply the caulk easily. Here are the steps for applying caulk around the base-

  • Clean the base so that there is no dirt or debris.
  • Apply the caulk so that the gap between the bathroom floor and the base is filled up with the caulk.
  • Use the caulking tool to finish the applied caulk.
  • Allow the caulk to sit for a day to completely cure.

Install the Toilet Tank & Turn on Water Supply

The installation of the toilet tank is the same as the removal. The only thing that you need to do is reverse the order.

So, follow the guide I’ve referred above to see what processes are to be followed for making it happen.

Once you do that, turn the water supply on and flush the toilet a few times.

Inspect and Analyze

Now, it’s time for the final inspection. Check if there are any leaks and also see if the new shims have solved the rocking toilet issue or not.

If everything is good, then you can sit back and relax. You’ve successfully installed a new shimmed toilet all by yourself!

Make sure to keep the bathroom floor dry so that you can quickly figure out if there are any leaks in the setup.

To Conclude

Installing a new shimmed toilet is not as difficult as it may sound. By following the steps mentioned in this guide, you can do it all by yourself without any professional help.

Just make sure to take your time and be careful while doing the whole process so that everything goes smoothly. Also, don’t forget to inspect for any leaks after installation.

I hope this guide was helpful and informative enough for you. If you have any questions or suggestions, feel free to leave them in the comments section below. I would love to hear from you!

Thanks for reading! Until next time!‚Äč

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