Step 1
Install the drain pipe in the closet bend. Push the pipe all the way down into the closet bend exactly as it will be installed when you finalize the connection.
Step 2
Trace around the edge of the drain pipe above the floor in the bathroom with a marker while holding the marker level with the floor, to mark where the drain pipe lies flush with the floor. If you have not installed the flooring yet, simply raise this measurement up on the drain to the thickness of your floor, or place boards that are a similar thickness to your flooring around the drain pipe before you mark the pipe. This simulates installed flooring.
Step 3
Remove the drain pipe from the closet bend and cut the pipe on the mark with a hacksaw or pipe cutting tool. Or, cut the drain pipe flush while installed on the closet bend with a small hand saw.
Step 4
Add PVC cement primer and cement to the drain pipe and closet bend, and insert the drain pipe in the closet bend. Assemble the remaining parts of the drain in the same way, if you choose to cut the pipe prior to cementing your connections.