Place the farmhouse sink face down on a piece of cardboard and trace the front of the sink onto the cardboard. Cut the cardboard out with a sharp utility knife. This gives you a template.
Tape the template onto the face of the cabinet with painter’s tape where you plan to install the sink. Place the top edge of the template flush with the top edge of the countertop. Trace the template onto the front of the cabinet with a marker. Discard the template.
Cut along the traced lines of the cabinet with a saber saw or reciprocating saw. Discard the unwanted section of cabinetry.
Cut two pieces 1-by-1-inch piece of pine to the length of the opening you cut into the cabinet with the saber saw or reciprocating saw.
Secure the first pine board inside the cabinet along the inside edge of the opening. Secure the second piece of pine along the back wall of the cabinet at the same height. This will add extra support for the additional height of the sink. Secure the boards to the cabinet with wood screws and a screwdriver.
Place the sink into the opening. Place a level on top. If necessary, use a wood file to remove additional wood to allow for proper placement. In addition, if necessary, wedge shim under the supports.
Secure the underside of the sink to the cabinet with the supplied brackets and screws.
Place a bead of silicone caulk around the top edge and front edges of the sink.
Place a bead of plumber’s putty around the hole in the sink basin and then secure the sink strainer to the sink basin with a pipe wrench. Wipe up excess putty with a moist rag. If your sink has two basins, repeat the process with the second basin.
Attach the S-trap to the drain extending up through the floor. Slide the downpipe extension into the S-trap. If you have a double-sink. Position the hole in the side of the extension pipe towards the other basin. Tighten the downpipe extension and the S-trap’s compression nuts with your hand. If you have a double sink. Attach the elbow to the second downpipe and then attach the elbow extension to the elbow and to the hole in the first downpipe extension. Tighten the compression nuts with your hand.