How to Install Toilet Shims

Written by nathan mcginty
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A wobbling toilet can start as a minor annoyance, but soon can develop into a major problem. The toilet is connected to the floor by bolts on the closet flange, where the sewage exits. Between these two is a wax ring used to keep in water and sewer gases. A toilet that rocks back and forth can damage this wax ring over time, causing water leakage. Fix a rocky toilet by installing toilet shims--normally short (2- to 3-inch) plastic inserts. If you can't find plastic shims, standard wooden shims will work just as well.

Skill level:
Moderately Easy

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Things you need

  • Toilet shims
  • Utility knife
  • Wrench
  • Level
  • Caulk

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  1. 1

    Cut away any caulk at the base of your toilet with a sharp utility knife.

  2. 2

    Loosen the flange bolts at the base of your toilet. These are usually covered by plastic caps. Undo the screws two or three turns with the wrench.

  3. 3

    Insert the shims underneath the toilet bowl where it is uneven. Use a level sitting on top of the tank to determine which way the toilet is leaning. Two or more shims may be necessary.

  4. 4

    Tighten the flange bolts down once the toilet is level. Tighten them hand tight to start, then one more turn with the wrench.

  5. 5

    Sit on the toilet to make sure it's no longer wobbling.

  6. 6

    Cut off any excess part of the shim(s) sticking out from underneath the bowl with the utility knife.

  7. 7

    Caulk around the base of the toilet.

Tips and warnings

  • Do not over-tighten the flange bolts--doing so can crack the porcelain.

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