Critical first step: figure out why it\'s loose
Most people assume a wobbling toilet just needs tighter bolts. Tightening bolts on a toilet that wobbles for the wrong reason will crack the porcelain. Diagnose first:
If the toilet rocks side-to-side: the floor isn\'t level (very common in old houses) — needs shimming, not tightening.
If the toilet rocks front-to-back: the bolts are likely loose — tightening may help.
If the toilet sinks or compresses when you sit: the flange is broken or the wax ring is failed — needs flange/wax replacement, not tightening.
If the toilet was solid until recently and just started rocking: the flange has shifted, broken, or the floor has rotted around it — investigate before tightening.
The correct tightening procedure
If diagnosis points to genuinely loose bolts:
1. Pop the decorative bolt caps at the base. Flip up the plastic covers — flathead screwdriver helps if they\'re sticky.
2. Check both bolts for engagement. Wiggle each one. If a bolt spins freely without tightening, it\'s broken — replace before continuing.
3. Tighten alternately, never one at a time. Snug the left bolt 1/4 turn, then the right 1/4 turn, alternating. Uneven tightening twists the porcelain and cracks it.
4. Stop the moment the toilet is firm against the floor. Don\'t go further. The wax ring is compressible — over-tightening keeps compressing it until porcelain cracks.
5. Use a torque wrench if available. Manufacturer spec is typically 25-35 in-lb. By feel: snug + 1/8 turn additional max.
If the toilet still rocks: shim it
The floor under most toilets is not perfectly flat. Shimming is the correct solution for rocking, not over-tightening. Procedure:
1. Slip plastic toilet shims (Cardinal Industries Shims, Bemis 7950) under the toilet base at the highest point of the rock. Push them in until snug.
2. Verify stability. Sit on the toilet — should feel solid.
3. Cut shims flush with a utility knife. Hide the cuts with a bead of white silicone around the base perimeter (skip the back 2 inches).
If the bolt spins without tightening
The bolt has stripped or broken its retainer in the flange. You cannot fix this with more wrenching. Either: (a) hold the bolt head from above with channel-lock pliers while turning the nut from below, (b) replace the bolt entirely — requires pulling the toilet to access the flange and drop in a new closet bolt, (c) if the flange itself is damaged, replace the flange.
The "torque it harder" mistake
I see this every month in plumbing forums: homeowner cranks the closet bolts to fix rocking, hears a crack, the toilet now leaks at the base because the porcelain base is fractured. The fracture is invisible from the outside but the toilet must be replaced. If the toilet rocks after snugging the bolts, diagnose further — do not continue tightening.