How To Install Undermount Sinks

Installing Undermount Sinks

Installing an undermount sink might seem like a complicated home improvement project. However, if you know a few tips that the pros use the project won’t be that difficult. Undermount sinks are typically installed under solid surface counter tops. The only difference between stone and acrylic counter tops is the way you fasten the clips that hold the sink in place.

All undermount sinks come with come type of metal clip used to hold the sink to the bottom side of the countertop surface. With an acrylic type counter top you can either screw the clips to the bottom of the counter top or you can epoxy them to the bottom. For stone counter tops you’ll need to adhere the clips to the bottom using an epoxy.

Make sure you follow the sink manufactures instructions on the placement of the clips and the number you need to use. The number is important because you won’t want the sink to fall when it’s fully loaded with hot soapy water!

The hardest part of installing the undermount sink is holding it in place while you install the clips. So that’s where a tip from the pros comes into play. Most counter top installers have a special bar and clamp system that spans the sink cutout and holds the sink in place (see the adjacent photo). You can accomplish the same thing with a 2×4 and a couple of ratchet bar clamps (see the lower photo).

Once you set up the beam and clamps you can easily adjust the sink to fit the cutout as you want. Once you’ve done a dry fit lower the sink back down a bit and apply a nice bead of silicon caulking and tighten the sink with the clamps. Re-position the sink to fit the cutout and make sure the counter top reveal is uniform around the sink.

Now you can climb inside the sink cabinet and install the sink clips. Once the clips are installed leave the beam and clamps in place for 24 hours so the silicon and epoxy can cure. The next day you can remove the clamps and install the remaining plumbing. You can by a Irwin Quick-Grip Clamp & Spreader from Amazon to help hold the sink in place.