How to Shim a Toilet

Are you sick and tired of the constant noises your toilet keeps making? It’s a problem that plagues many homes and businesses. When the toilet is not level, it can cause many issues such as water damage, leaks, and other issues; if your toilet is rocking back and forth, then maybe it’s time you learn how to shim a toilet! Shimming a bathroom is the most straightforward repair, but there are a few things you need to know before shimming it.

What is a Shim?

toilet shim

The shim is a small piece of wood, plastic, or metal that will fit between the base of your toilet bowl and your floor. They are used to level out an uneven floor or raise up a toilet that sinks too low on one side.

Toilets are designed to be installed at an angle to drain correctly. If the toilet is installed too vertically, it can cause water from the tank to leak into your home.

There are two types of shims used for toilets:

  • A wood or plastic wedge-shaped shim is inserted under a toilet’s base to raise it.
  • A flat metal shim is placed behind a toilet’s wax ring to center it between the floor and the tank.

Why You Should Use Shims

One of the most common problems with toilets is a wobbly toilet. If your toilet wobbles, it may be because the floor is not level or the wax ring has failed. These are both easy fixes, but shimming is an alternative that works well for small areas like bathrooms and kitchens.

Shims are a valuable tool for leveling a toilet, but they’re a simple solution that many people don’t know how to use appropriately.

Shimming a toilet is used to raise it to the same level as the surrounding flooring to prevent water from leaking below. As a result of this design, when the tank’s water pressure drops, the bowl will be able to refill itself more quickly, and there will be no leaks around the toilet’s base.

Because water no longer collects underneath it, it protects the toilet from harm caused by wear and tear. When building toilets with flush valves at the bottom of the tank or on one side, wax rings are utilized as seals. These toilets are less prevalent at home centers and hardware shops than flanged toilets.

toilet shim

How to Shim a Toilet

When you have a running toilet, it can be an awful experience. The water usage is wasteful, and it makes a huge mess.

To fix this problem, you need to shim the toilet to level it again. This will allow the water in the tank to drain properly again.

  1. Assess the situation

If your toilet is rocking back and forth or shifting from side to side, it’s time to shim it. Before you start, you should determine how much movement is acceptable.

If your toilet is rocking by more than 1/2 inch on soft floors or 3/8 inches on hard floors, it should be shimmed. If your toilet rocks less than that, then it’s probably fine. But if there is any doubt in your mind, do it.

  1.  Prepare your tools and materials.

You’ll need a few standard tools and materials to shim a toilet. You will need a tape measure, adjustable wrench, pliers, screwdriver, and a hammer. You’ll also need:

  • Plumbers putty or plumber’s wax. This is what will hold the new wax ring in place.
  • The new wax ring. The new wax ring should be clean and free of debris that might hinder its installation.
  • A plunger (optional). If there’s any clog in the drainpipe, you may need to use a plunger to clear it out before shimming your toilet. If you don’t have access to a plunger, try pouring some hot water down the drain first. This will usually do the trick if there are no obstructions in the pipes.
woman removing old wax ring with tools
Image from Simon Margolis
  1. Remove the old wax ring.

Use the cold chisel and hammer to remove the old wax ring around the toilet’s base. The easiest way is to start at one side and tap it until you break through. Then move to another spot on that side, and tap it again until you break through again. Continue this process until you’ve broken through all parts of the wax ring that are still attached to the porcelain. If debris is left from breaking through with your tool, use an old toothbrush dipped in mineral spirits or mineral oil to clean away any remaining residue from around where your new shims will go.

  1. Clean Up Debris

Clean up any bits of old flashing or other debris from around your existing toilet flange with a wire brush. If any rust is present, you may want to use an oxygen-powered wire wheel (available at hardware stores) to remove it before proceeding to the next step. If you don’t have an oxygen-powered wire wheel 2wsx available, use sandpaper instead so you don’t damage your porcelain finish!

  1. Level Out Surface

If your floor is uneven, use concrete blocks or 2x4s to level out the surface under your toilet flange (the part where the bowl bolts down). Ensure that both sides are level with each other so there will be even pressure on both sides of your new wax ring when you install it later.

  1. Leveling an Askew Toilet with Shims

Place a rubber mallet against the side of the base where it meets the floor. Tap until you feel it and make contact with the floor beneath. Make sure you do not tap too hard, or else you could damage your floor or crack your tile or wood floors.

Insert a wooden shim under each side of the base as far as possible so that there is about half an inch protruding from under each leg. Tap gently on top of each shim until all four legs are resting evenly on both base sides. Repeat until you have shimmed all four corners of the bowl.

When Should I Use A Shim?

When your toilet wobbles, it can signify that one or more of the toilet’s bolts is loose. This can cause a severe leak and lead to potential structural damage. It’s essential to get this problem fixed as quickly as possible.

You may need to use shims if your new toilet does not fit properly, but you can also use them for other reasons. For example, if you have an old bathroom that has sunk into the floor, you should use shims to bring it back to the proper height.

You can also use shims if you have an older model of toilet that was made before they were required to be Americans with Disabilities Act compliant by law. These toilets were built at various heights and may not fit properly in some bathrooms, which is where shims come in handy!

Shims are not designed for large movements, though. If your toilet is a few inches out of plumb but not enough that you can’t adjust it with shims, it’s best to hire a plumbing professional who has experience doing this type of work.


If your toilet rocks back and forth, there is no need to call a plumber. It is relatively easy to stabilize your toilet on your own and keep it in place. There’s no need to worry every time you flush. As long you follow the tips outlined above, you can rest assured that this is a temporary situation until you have time and possibly money to fix the problem. Good luck!

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