Originally Posted by Javiles
Damn it who
keeps bringing these old threads back from the dead, its like talking to yourself.
Google, Bing, or Yahoo.
I say there is nothing wrong with a plastic (white sheet Plexiglas) cutout of the outline of the toilet bottom to act as a large all around shim, although this may take some time to construct.
A well formed bead of mortar as a large all around shim works well except you can have a chicken and egg problem. The bead needs to fit the toilet accurately (or you need to add additional thin shims plus caulk to fine tune it) before you make the final installation with the wax ring. Whereas the best way to form the shim is to use the toilet itself, but then it is difficult to lift off the toilet for final assembly with the wax ring. I am guessing that the bead should be at least 2 inches wide so if it cracks into little pieces the pieces won't slide around so much that the toilet becomes undermined and loose.
It is of utmost importance that the toilet not rock or wobble during a test fit without the wax ring. Any movement of the toilet after the wax ring is in place will cause immediate failure of the wax ring.
It is of utmost importance that the toilet not touch let alone put weight onto the flange. This can cause the toilet to crack.
Oh, by the way, a DIY site is an excellent way to save face if you run into complications after starting a job (and have time to await a reply). Like lifting off the toilet and only after that finding that the flange is too high. By saving face I do not mean 100% of the time saying, "I'm not qualified so I'll get someone else in to finish or help out."