How to Install an Under the Counter Mounted Kitchen Sink

Under-mounted sinks allow you to clean countertops easily by pushing debris into the sink.

Most sinks are installed by dropping them into the countertop cutout from above. A popular alternative for natural stone countertops is an under-mounted sink. Under-mounted sinks are attached from below the countertop. Installing a sink this way adds a clean edge to the countertop that is not obstructed by a sink lip or ridge. Under-mounting allows the countertop to extend over the sink, leaving a small ledge around the basin. This helpful when you have a garbage disposal because you can just slide food scraps off the counter and into the sink. You should have the rough edge of your natural stone sink cutout polished to create a clean edge before attempting this project.

Things You'll Need

• Paintbrush
• Under-mount sink
• Silicone caulk
• Caulk gun
• 2-by-4-inch board
• Ratchet bar clamps
• Rubber gloves
• Two-part epoxy
• Under-mount sink clamps

Instructions

1. Remove all dust from under the sink cutout by dusting around the cutout with a paintbrush.

2. Set the sink under the counter and line it up with the cutout to test for fit. Set the sink aside once you have determined that it will fit the opening properly. Squeeze silicone caulk onto the rim of the sink. Set the sink under the sink cutout. Line the sink up to the cutout so it will set evenly. Press the sink upward so the caulk attaches under the counter, and have an assistant hold it in place while you complete Step 3.

3. Set a 2-by-4-inch board that is longer than the sink cutout on top of the countertop across the cutout. Attach ratchet bar clamps to the sink's drainage holes and to the board to secure the sink as the caulk sets up. Tighten the clamps in intervals until the sink is tight against the underside of the counter.

4. Follow the sink's instructions regarding the proper placement of the under-mount sink clamps that will hold the sink in place permanently (placement varies by brand). Put on rubber gloves to protect your hands from the epoxy. Attach the clamps to the sink lip and underside of the counter with two-part epoxy. Let the sink set for at least 24 hours.

Tips & Warnings

• If you're hanging an under-mount sink from an acrylic countertop rather than stone, you have the option of attaching the sink clamps with screws instead of epoxy.

References

• "Home Improvement 1-2-3"; The Home Depot; 2003
• Ask The Builder: Undermount Kitchen Sinks; Tim Carter; 2011
• Home Construction & Improvement: How To Install Undermount Sinks; June 22, 2008