How to Install an Undermount Sink on Quartz Countertop

Installing an undermount sink on a quartz countertop can seem intimidating, but with the right tools and careful planning, it is very doable as a DIY project. Here is a step-by-step guide on how to install an undermount sink on a quartz countertop.


Undermount sinks create a seamless look on quartz and other solid surface countertops. Since the sink rim is installed under the countertop, it gives a smooth transition from the countertop to the sink bowl. This makes cleaning easier as crumbs and spills can be quickly wiped into the sink without catching on an exposed sink rim.

Quartz is an increasingly popular choice for modern kitchen counters because it is durable, stylish, and low maintenance. While quartz is not quite as heat or scratch resistant as granite, it has excellent resistance to stains, chips, and cracks. This makes it a great surface for the heavy use of a kitchen sink.

Benefits of Undermount Sinks on Quartz

There are several advantages to pairing an undermount sink with a quartz countertop:

  • It creates a continuous smooth surface that is easy to clean.
  • The countertop edge remains exposed to showcase the beauty of the quartz material.
  • It has a very modern, sleek look.
  • Undermount installation allows for deeper sinks and larger bowls.
  • It avoids issues with spilled liquids collecting around the rim of a top mount sink.

Things You Will Need

Before starting this project, make sure you have the following:

  • Tube of clear silicone caulk that matches the quartz.
  • Caulk gun to apply the silicone.
  • Denatured alcohol to clean the countertop and sink edges before applying caulk.
  • Sharp utility knife.
  • Rags.
  • Painter’s tape.
  • Level.

Step 1: Cut the Countertop Opening

The first step is to cut the opening in the quartz countertop for the sink. This must be done very precisely to ensure the sink fits correctly.

Measure the dimensions of the sink and transfer those measurements to the countertop. Mark the opening carefully with a pencil. Use a straightedge and utility knife to score along the lines. Make several passes with the knife to cut through the quartz veneer. Go slowly to avoid cracking the quartz. You can also use a quartz wet saw for this step.

Once cut, the sink opening should fit neatly around the sink perimeter with gaps less than 1/8 inch.Sand any rough edges smooth with fine sandpaper.

Step 2: Install the Mounting Hardware

It is critical to install very sturdy mounting hardware under the countertop that will securely hold the weight of a loaded sink. This usually involves metal brackets, rails, or a wooden frame attached securely to the base cabinets.

Follow the mounting hardware instructions to attach to the cabinet base underneath where the sink will go. Make sure the hardware is level, flush with the cabinet front, and able to adequately support 200+ pounds before moving to the next step.

Step 3: Set the Sink in Place

Set the sink in place to check that it correctly fits the cutout in the quartz countertop opening. The sink edge should rest flat on the mounting hardware you installed without wobbling or rocking.

Remove the sink and thoroughly clean the underside of the countertop edge and the sink rim with denatured alcohol to remove any dirt or oily residue. Apply painter’s tape around the cutout opening to prevent silicone caulk from contacting the countertop surface during installation.

Step 4: Apply Silicone Caulk

Apply a bead of silicone caulk evenly around the top edge of the sink rim. Use a caulk gun to control the flow and make sure there are no gaps. The caulk provides the water-tight seal between the sink and quartz countertop.

Then carefully lower the sink into position, aligning it correctly within the countertop opening. Press down firmly so the rim makes full contact with the mounting hardware and quartz surface.

Step 5: Allow Caulk to Cure

It is important not to disturb the sink while the caulk cures and forms a tight seal. Remove any tape and follow the caulk manufacturer’s instructions for cure time. Usually at least 24 hours. A slight silicone haze may appear which can be removed with denatured alcohol after full curing.

Step 6: Make Plumbing Connections

With the sink securely mounted, you can now connect the faucet, drain pipes, supply lines, and other plumbing components according to the manufacturer’s instructions. Make sure to seal all connections with Teflon tape to prevent leaks under the sink. Turn on the water supply and carefully check for leaks before finishing up.

Step 7: Seal Between Sink and Countertop

Finally, apply a line of silicone caulk along the seam where the quartz countertop meets the sink edge. Smooth with a wet finger for a clean finish. Allow this caulk layer to fully cure before using the sink. This seals any remaining gaps and provides extra protection from moisture damage.

And that completes the installation! With proper planning and care, an undermount sink can be installed securely on a quartz countertop as a DIY project. Just take precautions at each step and allow plenty of time for the caulk to fully cure before use. With an undermount sink, you can enjoy an eye-catching, modern look on your beautiful quartz countertop.

Frequently Asked Questions about Installing Undermount Sinks on Quartz

Can I install an undermount sink myself or do I need to hire a pro?

With patience and the right tools, an experienced DIYer can install an undermount sink themselves. The process involves carefully cutting the countertop, mounting the sink correctly, and sealing it properly. If you are unsure, hiring a professional provides experience and accountability.

What types of sinks work with a quartz countertop?

Stainless steel, enamel, cast iron, and composite sinks are commonly used. The material is not as important as making sure you select an undermount sink basin specifically sized for your countertop cutout.

How do I cut the quartz cleanly for the sink opening?

Use a quartz wet saw for the cleanest cuts. For DIY without a wet saw, carefully score the outline with a utility knife then make several passes to cut through the material. Patrick the sink edge for a template.

Can I damages my quartz countertop when cutting the hole for the sink?

Cutting the quartz does carry a risk of cracking or chipping. Take it slowly, following the scored lines. Consider hiring a fabricator to cut the sink opening if you are unsure.

What is the best way to attach an undermount sink to quartz securely?

You need very sturdy mounting brackets and rails installed under the countertop that will support 200+ pounds. The sink edge rests on this hardware to hold the weight. Proper installation is key.

How long does the silicone caulk take to cure before using the sink?

It takes at least 24 hours for the caulk to fully set and create a watertight seal. Do not use the sink until it has completely cured or it could compromise the bond. Follow the caulk manufacturer’s cure time instructions.


Installing an undermount sink brings an elegant, modern look to a quartz countertop. While the process requires careful planning and patience, it can be completed as a DIY project. Precise sink cutting, sturdy mounting hardware, and properly applied caulk are the keys to success. With attention to detail, you can avoid leaks and enjoy a beautiful new undermount sink.