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How to Convert Your Sink to an Undermount

Denise Brown

An undermount sink allows you to set the sink below the countertop, even if the countertop is made of laminate. That means you have a smooth surface around the sink opening rather than the flange of a top-mounted sink. As you clean the countertop, items like crumbs can fall straight into the sink rather than getting stuck under the flange. To change sinks, even for laminate countertops, all you need are an undermount sink, an undermount sink conversion kit and a few basic tools.

Step 1

Turn off water to the sink. Disconnect the plumbing fixtures with an adjustable wrench. Remove the screws or clips holding the old sink in place.

Step 2

Mark the opening of the new sink on the countertop. For ease of installation, use a similarly sized and shaped undermount sink. For a laminate countertop, trim the top of the countertop, using a jigsaw, to fit the sink. Sinks typically come with a template to help with this step. Cut away substrate material under the laminate the width of the seal you are using, using a jigsaw.

Step 3

Mix the epoxy resin and hardener that comes with the ring’s installation kit in its container, following the manufacturer’s directions. Apply the resin in one continuous pass all the way around the top of the ring. Press the ring into position.

Step 4

Place installation bolts for the sink’s brackets in the locations specified by the sink’s manufacturer. Use a drill to insert the bolts in their proper location. Set these bolts in the underside of the composite material of the countertop with the bracket openings facing toward the sink’s opening. Do not tighten the bolts all the way.

Step 5

Apply sanitary silicone sealer all the way around the top of the sink’s flange in one continuous pass. Slide the sink into the bracket openings and press it up underneath the countertop. Tighten the bolts on the brackets with an adjustable wrench to secure the sink against the sink conversion seal.

Step 6

Install the faucet and drain fixtures in the new sink, following the manufacturer's instructions. Turn the water supply back on.