How to Install a Pre-Cut Granite Countertop With an Undermount Sink to a Vanity

Place the pre-cut granite countertop upside down onto the vanity base.

Wrap the threads of the faucet’s water connectors with Teflon pipe tape to aid in preventing water leaks. Place the tape around the threads going counter-clockwise for about four turns around the connector. Slip the faucet’s O-ring over the connector hoses and up over the base of the faucet.

Push the connectors through the faucet hole in the countertop and press the faucet base through the hole until the faucet is flush against the top of the counter. Push the mounting washer over the connector hoses under the countertop and over the faucet base, and then tighten the nut with a wrench to hold the faucet in place.

Pump a bead of silicone caulk onto the bottom of the countertop around the cut opening for the sink using a caulking gun. Turn the sink upside down to match the countertop and lower it onto the countertop, placing it so that the opening is centered with the cutout hole and the sides are pressed onto the bead of caulk. The caulk will aid in holding the sink in place as well as provide a waterproof seal between sink and counter.

Install the mounting hardware to hold the sink into place using epoxy adhesive. Place a bead of the adhesive to the side of the sink where each mounting bolt stem is needed. Check the manufacturer’s instructions for exact placement. Press the stem into the epoxy. Install the mounting clips for the sink next to each of the bolt stem locations, using epoxy for the clips as well. The clips go over the rim of the sink and sit parallel to the bolts stems. Allow the mounting hardware 15 minutes drying time.

Place the bolt over the clip and into the stem, and then screw it into place using a wrench until tight. This will give the sink added support and prevent movement once you mount the countertop.

Lift the countertop. Use a helper if the top with sink is too heavy to lift alone. Flip the countertop over and then place onto the vanity base, right side up.

Tilt the countertop upwards at the front and place a bead of caulk onto the vanity’s edge along the top of the cabinet. Lower the granite countertop back onto the vanity, using the silicone caulk as an adhesive. Allow the caulk to set for 24 hours.