When you find that floor modifications, like new tiles, have raised your toilet above the height of the original drain ring, what do you do? asks Cliff.
There are several solutions to extend up over a 1/4 to 1 inch gap.
First there is a wax ring, the kind with the plastic funnel down the middle, that simply has more wax. It is called a Wax Extender Kit.
You can also get plastic rings with foam gaskets that screw onto the top of the existing floor ring. One is 1/4 inch thick and the other 1/2 inch thick which will allow you 1/4, 1/2, or 3/4 inch extension. Then you put the wax ring on top of that. Apparently some plumbers are worried about the foam gasket drying out over time so these particular plumbers don't recommend this high up in the house where you have finished ceilings below. If you want to use them and are worried, simply silicone caulk the joints between the rings to back up that foam.
For more than 1 inch separation, it is best to cut into the drain pipe below, add an extension sleeve and rebuild the floor ring at the new proper height.