I am installing a tiolet in a basement with a concrete floor. After I dig out the space for the drain line I intend to pour concrete back over it. Do I sleeve the flange bottom at the drain connection to keep the concrete from setting around it? Is it required to glue the flange junction with the drain line? (I case of future new flooring being installed)
Yes, special sleeves are available depending on the size of the pipe that you are using. Try to get the pipe as even with the floor as possible. You can ask for these sleeves at your local plumbing supply. After your concrete sets up then the flange can be glued on. If your stubbed up pipe is a little to high, use an internal pipe cutter (small grinding disc attached to your cordless drill) these are also available and inexpensive.