How to Install an Undermount Sink | I Hate My Sink

Installing an undermount sink is one of the best ways to give your kitchen a clean, modern look. Unlike a drop-in sink, an undermount is attached underneath the countertop, leaving a smooth surface for easy cleanup and a stylish finish. While it takes careful prep and secure mounting, you can tackle this project with patience and the right tools.

Before You Begin

Before installing your new sink, double-check that it’s the right size for your countertop cutout. Remove your old sink and clean the area thoroughly, ensuring the underside of your countertop is free from old adhesive and debris.

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1. Prep and Position

Start by dry-fitting the new sink to ensure it aligns perfectly with the opening. Most undermount sinks require support until the adhesive cures, so gather a sturdy 2x4 or adjustable braces to hold the sink in place from underneath while you work.

2. Apply Sealant

Run a continuous bead of high-quality silicone sealant around the edge of the sink opening underneath the countertop. This creates a watertight bond that keeps moisture from seeping into the counter material.

3. Mount and Secure

Carefully lift the sink into place beneath the countertop. Adjust its position until it’s centered and flush with the edges. Have a helper hold it steady or use your braces to keep it tight against the counter.

Next, attach the sink clips or mounting brackets that came with your sink. Space them evenly around the perimeter for balanced support. Tighten each clip gently, moving from side to side to keep the sink level as you secure it.

4. Wipe and Cure

Before the silicone fully cures, wipe away any excess that squeezes out along the edges. Double-check that the sink is still properly aligned. Leave the supports in place and allow the adhesive and sealant to cure fully—usually overnight—according to the sealant manufacturer’s instructions.

5. Connect Plumbing

Once the sink is secure and the sealant has set, you’re ready to reconnect the drain, faucet, and garbage disposal if you have one. Run water and check for any leaks. Tighten connections if needed.

Enjoy Your New Undermount Sink

With the sink securely installed, you’ll enjoy a sleek, easy-to-clean workspace that makes wiping crumbs and spills directly into the basin a breeze.

At I Hate My Sink, we love helping homeowners tackle simple upgrades that make a big difference in daily life. If you’d rather skip the hassle and have your sink installed by pros who do it right the first time, we’re here to help.

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