How to Install An Undermount Bathroom Sink To A Granite Countertop Without Clips

Slicing a sink-sized hole in a granite countertop is hard enough, so worrying about drilling holes at the perfect depth to mount clips can add to the challenge.

But since nearly every guide you’ll find online advises using strong construction adhesive to secure the sink, are the clips actually necessary?

If not, it’d really simplify the installation process, especially when working with natural stone counters like those crafted from granite slabs. So, what’s the verdict? Let’s find out.

Do Undermount Sinks Need Clips?

Generally speaking, it’s best to have clips as an extra layer of security when installing undermount sinks. Unlike drop-in sinks, undermount models don’t have a rim resting on the countertop to support their weight.

Instead, these sinks dangle beneath the countertop, relying on clips, caulk, and strong adhesive to firmly adhere them in their places. The sink might pull away from the countertop without clips or mounting brackets, creating an unsightly mess.

Undermount Sink

We’ve heard horror stories of kitchen sinks pulling away from their mounting place due to a lack of brackets or clips.

But what about bathroom sinks? Could you install an undermount bathroom sink without clips?

While you could, it might not be the best idea, especially if you plan to place heavy objects in the sink.

For example, consider an undermount kitchen sink secured with nothing more than adhesive. Let’s say you fill the sink with water and have a few heavy pots cooked on food soaking in the sink.

The sheer weight becomes too much for the adhesive, sending the basin for a tumble into the cabinet below. With clips or brackets, the chances of this occurring would’ve decreased significantly.

So, in the bathroom, while you could install it without clips, it’s usually best to use them. That said, installing the sink without brackets or clips might be perfectly fine, particularly in a rarely-used bathroom where the sink is unlikely to carry heavy objects.

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There appears to be a lack of consistency across the board, as some industry professionals advise clips or brackets while others fail to mention them altogether.

Generally speaking, it’s best to install undermount kitchen sinks with brackets due to the weight they’ll bear, but some bathroom sinks can get by without them.

We’ll walk you through the steps of installing an undermount bathroom sink in the following sections, but it’s important to remember the risks of an improper installation.

Installing an Undermount Bathroom Sink on Granite Without Clips

Undermount Sink

If you decide clips aren’t a necessity for your bathroom sink installation, you can proceed with your project without attempting to drill holes in the granite safely. The following sections walk you through this process step-by-step.

Gather Your Materials

First, you’ll need to gather the necessary tools and materials to complete the job. Here’s what you’ll need:

  • Supplies to cut a hole in the granite, if you haven’t already done so
  • Denatured alcohol
  • Clean rags
  • Silicone caulk
  • Construction adhesive or two-part epoxy
  • Bar clamp
  • A chunk of a 2×4

Cut a Hole

If you haven’t yet sliced a sink-sized hole in your countertop, now’s the time to do it.

Be careful while cutting through the counter, as granite can be tricky to work with, but mistakes are expensive. Use the supplied template, if there is one, to measure the correct hole size.

If the sink didn’t come with one, flip it upside down over the underside of the countertop and trace the outline onto the counter. Adjust your measurement by half an inch, or based on the reveal type, you want to ensure the hole isn’t too big.

Clean Up

Before you begin, clean up your workspace and countertop to ensure you start with a clean work surface.

If the granite countertop isn’t yet installed, you can place it upside down over two sawhorses for easier access. Conversely, if the countertop is already installed, you’ll have to work carefully in the small space in the base cabinet beneath it.

Start by removing dirt and grime from the granite using a clean rag dampened with denatured alcohol. Dust and debris can interfere with the glue’s ability to adhere, so taking your time with this step is essential.

If you’re working with an installed countertop, we recommend clearing out the base cabinet entirely for easier access.

Prep Your Materials

Once the alcohol dries and the surface is sparkling clean, it’s time to prepare your materials. If you’re using a two-part epoxy or a similar option that requires preparation, now’s the time to do it.

Follow the instructions on the manufacturer’s label to ensure proper preparation. Remember to abide by any recommended resting or waiting periods before using it on your sink.

Apply Adhesive

Once your adhesive is ready, apply it to the outer edge of the sink rim. Avoid using it too close to the inside edge, as overflow could ooze into the basin and create an unsightly mess.

If you’d like, you can apply a bead of silicone about ½-inch away from the adhesive to create a snug, watertight seal.

However, if you’re installing the sink on an installed countertop, you may find it easier to wait on this step. You can wait until the adhesive dries and the sink is securely in place before applying the caulk.

Clamp for Drying

After applying adhesive, position the sink in place, carefully aligning it with the hole to ensure an even, professional-grade reveal. Once you align the sink properly, push it into place to create contact between the countertop, adhesive, and sink rim.

To ensure solid contact while the adhesive cures, place a piece of 2×4 on the bottom of the sink and position a bar clamp on it.

The 2×4 will protect the bottom of the sink from the clamp. Tighten the bar clamp against the countertop to keep the sink securely in place.

If the sink moves when you’re tightening the clamp, simply wiggle it back into place while the adhesive is still wet. Once you like the position, tighten the clamp and let it sit until the adhesive cures according to the manufacturer’s instructions.

Add a Watertight Seal

Once your sink is firmly in place and the adhesive is set, apply a bead of caulk around the edge.

The caulk will help create a watertight seal to ward off water damage in your base cabinet, so this is an important step. If you added caulk at the same time as the adhesive, you can skip this step.

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Apply the caulk around the inside edge of the sink where it joins with the countertop. Use a damp finger to smooth the caulk and create a finished appearance.

Add Finishing Touches

Once the caulk cures according to manufacturer instructions, your last step is to add the finishing touches. Install the drain assembly and connect it to the plumbing. Install the faucet and connect it to the water lines.

Once you install the faucet, check the sink for signs of water leakage around where the sink meets the counter.

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