How to Fix a Rocking Toilet

Wobbling is more than just a minor annoyance; it is a direct threat to your home's plumbing integrity. When a toilet rocks, it places stress on the wax ring seal between the porcelain horn and the sewer flange. Over time, that movement breaks the seal, allowing sewer gases to enter your bathroom and wastewater to seep into your subfloor, which leads to rot and expensive structural damage. Fixing this is a Saturday morning win that prevents a massive headache later. The goal is a rock-solid base that doesn't budge under pressure. Once you clear the wobble, you seal the base so that water stays where it belongs and the fixture remains locked firmly against the floor.

1. Tighten the Mounting Bolts. Remove the plastic bolt caps at the base of the toilet. Use an adjustable wrench to gently tighten the nuts on the closet bolts, taking care not to overtighten and crack the porcelain.
2. Identify High and Low Spots. Place a bubble level across the toilet bowl to identify the high and low spots. This helps you determine exactly where you need to place your shims to stop the rocking.
3. Wedge Shims Under the Base. Slide plastic shims into the gap between the toilet base and the floor until the toilet is perfectly stable. Do not use wood shims, as they will rot if they get wet.
4. Score and Snap Excess Shims. Use a sharp utility knife to score and snap off the portions of the shims protruding from under the base. Cut as close to the toilet as possible for a clean look.
5. Seal the Perimeter with Caulk. Run a bead of 100% silicone bathroom caulk around the base of the toilet where it meets the floor. Leave a small two-inch gap at the very back of the toilet to allow for drainage if a leak occurs in the future.
6. Let the Caulk Cure Fully. Wait at least 24 hours before using the toilet to ensure the caulk is fully cured and watertight. Avoid cleaning the base with harsh chemicals during this time.