Inset sinks, also known as drop-in sinks, fit into an opening in a laminate, tile or marble countertop and have a rim that rests on the countertop. Special brackets, known as sink clamps, fit into rails at the underside of the sink and secure it at the underside of the countertop. The countertop installer uses the particular sink you’ve selected as a template to cut the opening and drill holes for the faucet fixture. After the opening is cut and the holes drilled, fitting an inset sink in the countertop takes a relatively short time.
Place cardboard on the countertop near the cutout opening. Turn the sink over and place it on the cardboard.
Install a tube of clear silicone sealant in a caulking gun. Cut off the tip of the tube to make a 1/8-inch opening using a utility knife. Apply a uniform bead of sealant at the underside of the sink's rim, 1/8 inch from the outer edges of the rim at all sides. If the sink has machined holes for a faucet fixture, apply sealant around the holes, 1/8 inch from the edges of the holes.
Turn the sink upright and grip it at the hole for the drain. For a double sink, use both hands and grip each hole. Place the sink in the opening in the countertop, making sure that machined holes align with the drilled holes in the countertop. Move to the underside of the sink.
Adjust the position of the sink so the spacing between the edges of the opening in the countertop and the outer sides of the bowl, or bowls, are equal and uniform.
Position a sink clamp at the midpoint of the rail at one side of the sink, with the head of the clamp-bolt pointing down. Fit the hooked end of the bracket into the rail and hold the bracket against the underside of the countertop with one hand. Secure the clamp in place by tightening the bolt against the underside of the countertop with a nut driver or open-end wrench.
Repeat the previous step and install a clamp at midpoint of the rail at the opposite side of the sink. Install the remaining clamps at 4-inch intervals at each rail.