The toilet flange is connected to a sewer waste line. What is that material? Is it cast iron or vitreous china pipe, or is the flange glued to plastic ABS? Look at the Flange. See that it has screws to hold the toilet bowl down, but it also has screws into the concrete? Remove those. Is the flange bronze or plastic, or steel? See if you can lift it out of the waste pipe. If the waste pipe is cast iron, you can chip the concrete around its outside, cut a very short nipple to the correct height for the flange to raise to the new floor level, add a fernco coupling, and then install a new flange, for permanence. If the flange is ABS and is glued to ABS heavy wall, you could possibly insert an inside cutter to remove the pipe below the coupling, chip the concrete, cut a short nipple to the correct length, add a glued on coupling, and glue on a new flange , for permanence.
: My basement toilet bowel flange is set in concrete (what the toilet is attached to). I want to raise the floor by about 2 1/2 inches (make a wood floor). What could I use to put in the floor drain system to have a solid attachment for the toilet attach to. I have already tried double wax rings, and it leaks. I want something a bit more permanent. Thanks for any help. Dave