Undermount Bathroom Sink – Installing a bathroom sink under a granite countertop deck requires precision, accuracy, and proper mounting techniques to prevent it from separating from the bottom of the countertop and falling into the cabinet below. In addition to the mounting accessories that come with a retail sink kit, you will need epoxy putty to solidly attach the sink to the granite. Properly installed, an undermount sink attaches to the underside of the counter, allowing the countertop surface to serve as the lip of the sink basin and rationalizing the counter surface.
Measure the width of the sink cutout and cut a 2-inch by the 4-inch length of wood slightly longer in size using a handsaw. Wipe the underside of the granite countertop with a dry cloth to remove accumulated dirt or debris that may prevent the epoxy from establishing a strong bond. Apply an even coat of silicone sealant around the top edge or edge of the undermount bathroom sink. Run the putty evenly so that it covers the entire surface.
Hold the undermount bathroom sink and raise it with its caulked lip centered in the opening in the granite counter. Push the sink against the bottom of the countertop. Place the 2-inch by 4-inch wood above the sink cutout on the top of the countertop, directly through the sink opening. Push one end of a grab bar into the sink’s large drain hole and the other end through the 2-inch by 4-inch lumber.