You might need to upgrade your bathtub trap to a P-Trap to hold in water more efficiently and keep clogs out of the drain. This is a moderate installation that almost anyone can perform from home. It only costs around $100 to $250 to finish, and you also save by not calling in a plumber to do it for you. Make sure to set aside at least a day or two of time to complete the project. Perform the following steps prior to fitting a new bathtub, or you will have to remove the bathtub to install the P-trap.
Step 1: Cutting the Floor
You will want to make sure there is enough room to replace and install the P-trap. Cut around the floor, giving yourself enough room around the drain to easily access where the P-trap has to go on the drain.
Step 2: Measuring and Cutting Plywood
Cut the plywood on the floor using a circular saw. Mark with a pencil where you would like the cuts to be made prior to cutting. Cut along 4 lines around where the drain is using a plunge cut. Then cut the board you take out in two using the reciprocating saw. Pry up the pieces of plywood to remove them from the drain.
Step 3: Positioning
Use the reducer to change the drain line from the 1½-inch to a 2-inch drain. Apply some ABS glue to the pieces, and press firmly down on them together to secure them. Place the P-trap in the exact location on top of the drain to prevent any mistakes from happening when using the bathtub.
Step 4: Installing
Use a piece of plywood to fit back over where you have already cut through. You will want to measure the length from the P-trap to the top hole in the plywood. The P-trap should come above the top of the plywood, and if it does not then attaching a piece of ABS to the P-trap to the top of the plywood will do. Screw the plywood to the floor, and into the floor joists, and attach the drain to the P-trap.
Make sure to exercise precaution when it comes to installing hardware on your own into your home. Follow all state and county guidelines to ensure you’re following all of the regulations and codes they have set forth.