I recently applied a concrete patch to a rough/very uneven piece of concrete beneath an old flange I ripped out. I originally was going to apply a concrete leveler to the floor so I didn’t ensure the patch was completely level under the flange. Then decided I didn’t need the leveler (forgot about my patch issue).

My flange rocks a bit when I insert it dry - maybe a 1/4 inch gap in one area due to the concrete patch being higher there.

Will I be able to install the toilet as is? Should I try using mortar to raise up the section of the flange that is slightly lower? Do I need to use concrete leveler across the entire floor to even this out? enter image description here enter image description here

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1 Answer 1


You can use composite shims. The main thing is to make sure it is supported you don't want the weight of the toilet and someone on it to crack the flange. Mortar can work too. Plumbers have been know to use pennies.

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