installed new toilet and flange in concrete basement floor but on top of tile. Toilet rocks slightly back and forth, not sideways but front to back. Did I maybe not get flange tight against tile ? What might I check for? no problem removing as It has not been used yet. Thanks


There are plastic wedges designed to stop rocking of toilets. Don't try to stop the rocking by tightening the floor bolts.


In my experience you won't get a dead-solid mount on a hard floor about 90% of the time. The toilet base and the tile are too likely to have imperfections that affect the connection.

So, rely on caulk. Clear, 100% pure silicone in a bead pressed into the void under the toilet will make it solid. I usually do the front and sides, but leave the back open. It's not necessary to do the back and it's a good place to leave a leak indication drain.

If you don't trust your caulking skills, mask the floor directly under the outer edge of the toilet base (or slightly inside). Inject the caulk in small beads and work it into a cove with your finger. Add more only if it presses in too far.

Give it a few hours to fully cure and be happy.

  • 3
    I caution not to completely seal the toilet base with caulk because it can hide the presence of a leak caused by failed wax ring... leading to extensive subfloor damage. Leave a good size gap in a hidden area. – Jimmy Fix-it Jan 7 at 6:11

I used to remodel a lot of bathrooms. As long as the flooring at the base of the toilet is sound, I second the use of plastic shims to level it and then caulk the base. That's the best solution

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