How to Mount an Undercounter Sink to Concrete
- 1). Clean off any debris or foreign materials from the underside of the counter around the location for the new sink using a small wire brush. This removes unwanted materials and lightly scuffs the concrete.
- 2). Place the sink in position under the counter and have an assistant hold it in place while you mark the location of mounting holes in the concrete with a permanent marker. Plan to use at least two clips per side and more if the sink is heavy.
- 3). Measure down 1/2-inch from the tip on a 3/16-inch masonry drill bit and make a line around the bit with the marker to indicate the measurement. Insert the bit in a power drill and drill holes at each of the marks on the underside of the concrete countertop. Stop drilling when the bit is in the concrete up to the marker line to prevent drilling all the way through the material.
- 4). Squeeze a few drops of concrete adhesive into the drilled holes, and apply a 1/4-inch diameter bead of silicone caulk on the lip of the underside of the counter. Position the sink under the counter again and align the mounting holes with the new drilled holes. Have the assistant push the sink up into the caulk to form a seal and hold it steady.
- 5). Push concrete anchors into each of the holes and begin inserting screws through the sink mounting holes and into the anchors. Tighten the screws down with a Phillips screwdriver until they are snug and the sink is tight to the concrete.
- 6). Position a cut piece of 2-by-4 lumber under the sink to support it for 24 hours while the anchors bond with the adhesive and the concrete. Add the drain piping and water faucet when the sink installation is finished.
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