To install toilet shims, use a carpenter's level to ensure that the toilet bowl is level, then push the shims in place to keep the toilet from rocking, preventing water and sewer gas from leaking underneath. Use a utility knife to cut away any excess parts of the shims, then caulk to seal them in place. Plastic shims are preferred, but if you can't find toilet shims specifically of that material, you can use any plastic construction shims.
- Level the bowl
Slide the shims under the toilet to prevent further rocking from occurring. Place the carpenter's level across the top of the bowl. Adjust the shims until the spirit bubble is between the lines when you place the level on the bowl from front to back as well as from side to side. Tighten the closet bolts on either side of the base of the bowl to ensure it is snug.
- Cut off the excess shim
Use a utility knife with a sharp blade to cut away any part of the shim that extends from under the bowl. Be mindful not to cut yourself or the flooring under the toilet.
- Caulk any gaps
Use the plumbing caulk to apply an even bead between the bowl and the floor. Use the caulk to hide the shims from view. Allow the caulk to dry before using the toilet again. Replace the covers on the closet bolts.