Toilet Shims: What They Are and Why They’re Important

Toilet shims are rubber or plastic tabs that people use to level wobbly toilets. Some toilets can be installed on uneven floors, or the toilet flange can be too high from your bathroom floor. In either case, toilet shims will be necessary to level out your toilet.

In this article, we will go through exactly why you need to shim a toilet if it begins to rock. Also, we will go through the steps needed to shim a toilet properly as well as a few extra things to keep in mind when using these shims to level your toilet.

white toilet next to shower

Why Is It Important to Shim a Wobbly Toilet?

There are many problems that come with a wobbly toilet. The first and most obvious issue is that the toilet may just come off with you on it. Toilets are very heavy and taking a fall off of one can damage more than just the toilet itself.

Also, the wax ring under the toilet will come loose if it rocks around too much. The wax ring seals the toilet flange and the toilet itself together so that sewage fumes do not leak out. Needless to say, there are all kinds of health hazards to be wary of if the wax ring comes loose.

Plus, if this wax seal comes loose, you will likely spring a leak underneath the toilet that will stink and make your bathroom floors slippery and dangerous. So, shimming a toilet that has come loose or is being installed on an uneven surface should be done immediately so that you may avoid these problems.

How to Shim a Toilet

Step 1: Turn Off the Water

For most toilets, there is a valve on the left side that can be turned clockwise to shut off any water going to it. Once you’ve turned the water off, hold the toilet’s lever down to flush it and get out as much water as you can.

Then, using a sponge, get rid of whatever water is left in the tank and bowl. After that, disconnect your water supply line, which can be found connected to your shut-off valve. You may need a wrench to loosen this, but try to use your hands to unscrew it at first.

Step 2: Take Off Your Toilet

Next, take the bolts that screw your toilet to the floor off. Be sure to not crack the porcelain surrounding these bolts as it can’t be fixed and will require you to replace your toilet. 

Rock the toilet back and forth to break the wax seal, lift the toilet off of the flange, and place it in a safe place to put back on later.

You will see the drain pipe connected to the toilet once you take it off. You should plug this quickly with an old towel or rag to keep any sewage fumes from stinking up your bathroom and causing you to get sick.

Get rid of the old wax ring and scrape off any old wax from the toilet and toilet flange. Check to see if the toilet flange is still in good condition and, if it is, move on to the next step.

Step 3: Put in the New Wax Ring

Putting on a new wax ring is fairly easy. To put on a new wax ring, slide it into the toilet’s outlet carefully. You will also want to make sure it does not become deformed while you are placing it. Then, flatten it out, and you will be good to put the toilet back on top of it. 

Step 4: Put the Toilet Back on and Shim It

Now, take the towel or old rag out of the drainpipe and lift your toilet above its flange. Make sure it is aligned with the bolts and place it down slowly. You may need some help with this if you have trouble lifting the toilet. Having a second set of hands helps a lot when moving a toilet.

Then, slide your shims into the necessary places and push them in gently so that they’re snug. Now, screw the bolts back onto the toilet in alternate intervals to keep it level. Make sure to not screw them too tightly so that you do not crack the porcelain.

Finally, sit on the toilet and lean a little bit in every direction to make sure it is completely sturdy. If everything checks out, cut the ends of the shims so that they are no longer visible and move on to the final step.

Step 5: Reconnect the Water Supply

Reconnect your water supply line in the same way it was connected initially and turn the valve to allow water to come back in. Then, flush a couple of times to make sure water is flowing through properly and there aren’t any leaks.

Once all of this is done, your toilet has been successfully shimmed and can be used without any worry of it leaking sewage fumes or falling off its seal anymore.

Things to Keep in Mind When Shimming a Toilet

Before you do anything with the shims, you will have to mark exactly where your shims should go. This will involve you either using a level to see where your toilet is leaning or rocking the toilet slightly by hand to see where a shim is necessary.

When adding shims, make sure they are going on both sides in order to distribute the weight of the toilet evenly. Whenever you add some shims, give the toilet a test rock to see if there are any other spots necessary to shim.

If your toilet is already leaking, the shims will not fix this problem as well. Leaks below your toilet usually mean the wax seal is broken and needs to be replaced as soon as possible. Once your wax seal is fixed, then you can shim the toilet without any other problems.

Also, be sure to push the shims in with your hands. Many people will make the mistake of tapping the shims in with a hammer, which can easily unsettle the wax ring and cause you to have to take the whole toilet off again and get a new wax ring.

Time to Get Started

Hopefully, you now have all the knowledge you need to properly use shims to fix your wobbly toilet. Be sure to follow the steps above carefully because this is a job that can go wrong in many ways if it is not done carefully.

Also, remember to keep in mind that you should mark the exact spots where you want the shims to go. Other than that, best of luck in repairing or installing your toilet using these very helpful tools that, in many ways, are a plumber’s best friend.

1 thought on “Toilet Shims: What They Are and Why They’re Important”

  1. Make sure to remove the reinforcement ring that comes with some wax rings (Reinforced wax rings, like Oatey’s in the red and white box; the black and white box is only the wax). This black plastic ring on the bottom of the wax ring can stick to the bottom of the toilet, making inexperienced homeowners (like me!) think it is an integral part of the toilet, instead of part of the wax ring which should be completely removed, reinforcement and all. I went through 2 reinforced wax rings and 1 of the FluidMaster rubber rings before realizing that the black plastic piece wasn’t a part of the toilet.


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