How to Retrofit a Vanity Top to a Bathroom Cabinet

Shut off the water to the old sink top’s faucet by turning the valve handles under the sink clockwise until they stop. Turn on both the hot and cold water on the faucet to release any leftover water in the supply lines. Place a bucket under the faucet and drainpipes under the sink.

Twist the nuts on the end of the water supply lines counterclockwise using a basin wrench. Remove them from the water supply valves and the underside of the faucet. Turn the slip nuts connecting the sink’s drainpipes together counterclockwise to break the connections. Remove the pipe sections, dumping the water in the trap piece into the bucket.

Back out any screws holding the counter to the cabinet from inside the cabinet. Cut through any caulk between the counter or attached backsplash and the wall with a utility knife. Pull up on the counter to remove it from the cabinet. If the counter is still attached to the cabinet, drive a pry bar between the cabinet and counter to break up any adhesive.

Measure the width and depth of the cabinet twice to be sure your measurements are accurate. Measure the width and depth of the underside of the new countertop, from the underside of the counter and without including the lip on the underside of the counter in the measurements, since the lip extends beyond the edge of the cabinet.

Apply an even coating of silicone caulk to the top edge of the cabinet. Lower the counter onto the cabinet. Thread the new water supply lines onto the connections on the supply valves and the underside of the sink’s faucet. Thread the drainpipes back together, cutting any pipes that do not fit straight with a hacksaw. Restore the water to the sink’s faucet by turning the handles on the supply valves counterclockwise.