How to Install a Bathtub Drain From the Center to Right Side

Maneuver the bathtub into the place where you plan to install it. Insert a pencil into the drain hole and mark the subfloor beneath, drawing a circle so you can find the center of the drain. Move the tub back out of the bathroom.

Draw a 12-by-12-inch square around the circle you marked on the subfloor. Unscrew the subfloor from the floor joists with the drill, pulling up the plywood sheet with the square and circle drawn on it as well as any sheets between that one and the wall containing the waste stack. Cut out the square you drew on the subfloor with the reciprocating saw.

Mark the route the bathtub drainpipe will need to take to reach the main waste stack. Draw lines on the floor joists with the pencil to note where the center of the pipe should be. Bore holes in the floor joists you marked with the hole saw. Use a bit that creates a hole 1 ¾-inch in diameter.

Dry-fit the PVC pipe sections together, hooking them to the main waste stack vent and running them under the tub with the PVC trap centered under where the bathtub drain will be. If the length is off, cut down one of the PVC lengths with the hacksaw until everything fits. Disassemble the PVC and reconnect it, this time sealing each length to each connector with the solvent glue.

Screw the subfloor plywood back down into place on the floor joists with the drill. Move the tub back into place.

Roll a wad of plumber’s putty between your hands until you have a cylinder as thick as the under-rim of the drain flange in the drain assembly. Install the drain assembly according to the manufacturer’s instructions. Typically, you press the plumber’s putty into the under-rim of the drain flange, then install the drain flange in the drain, pressing the drain body down to where it meets the upper portion of the PVC trap. Connect them using a compression nut. If your tub has an overflow plate, you should connect that at the same time.