Measure and mark the location on the drywall and then cut out a piece of the drywall using a drywall saw. You may want to replace old-looking plumbing. Pedestal Sink Installation Pedestal Sink Bathroom Renovation Cost Replace Bathtub Faucet Then make a mark 10 inches from the wall accounting for the baseboard.How to replace a bathroom pedestal sink. This distance for this mark may vary with different sinks Center the pedestal on the mark and set the sink tight against the wall. Place a sink flange wrench into the opening and slip the tools prongs around the flanges center. If desired move the stop valves closer to the trap in order to hide them behind the pedestal. Cut a 2x8 lumber board to fit snugly between the studs. Remove your old vanity and sink if necessary. Then set the sink and pedestal aside. See below for a shopping l. This will give you all the room you will need to repair or fix any plumbing or draining issues. The first thing you need to do is shut off the water to the bathroom sink. Move to the top of the pedestal sink and locate the opening to the drain known as the sink flange. At a minimum the sink will tear the drywall and in a worst-case scenario you may have to break the sink to get it off. Following the product instructions install the hardware for mounting the sink to the wall. To break the glue bond slip a stiff metal putty knife behind the sink and tap it with a hammer. You can try to replace the drain without r...