How to Install an Undermount Sink in a Quartz Countertop

Installing an undermount sink in a quartz countertop can seem daunting, but with proper planning and the right techniques, it can be a straightforward DIY project. Here is a comprehensive guide on how to install an undermount sink in a quartz countertop.


Undermount sinks are a popular choice for modern and contemporary kitchens. Unlike drop-in sinks, which sit on top of the countertop, undermount sinks are installed from beneath the countertop, creating a seamless and stylish look. Quartz has become a coveted countertop material in recent years due to its durability, easy maintenance, and stylish appearance. Quartz is an excellent complement for an undermount sink.

When installing an undermount sink in quartz, proper preparation and careful attention to detail are essential for a successful outcome. With the right process, you can have a stunning undermount quartz sink that will be the focal point of your kitchen.

Benefits of an Undermount Sink

Here are some of the benefits of installing an undermount sink in quartz:

  • Creates a seamless, modern look between the sink and countertop.
  • Easier to keep clean since there is no lip or crevice for dirt and grime to collect.
  • Quartz is stain and heat resistant.
  • Undermount installation preserves more countertop workspace.
  • Quartz comes in a wide variety of colors to complement your sink.

Things You’ll Need

Before starting the installation, ensure you have all the necessary supplies and tools on hand:

  • Undermount sink designed for quartz installation
  • Silicone adhesive sealant made for quartz and sinks
  • Quartz countertop with pre-cut sink opening
  • Rags, acetone, and adhesive remover
  • Safety glasses and gloves
  • Carpenter’s square
  • Pencil
  • Screws appropriate for quartz
  • Caulking gun
  • Custom sink-mounting brackets
  • Drill and drill bits
  • Router (for trimming countertop if needed)

Step 1: Check Sink and Countertop Dimensions

The first step is to check that your sink dimensions match the pre-cut opening in your quartz countertop. The sink rim should sit flush with the bottom of the quartz. If the sink doesn’t fit precisely, you may need to have the quartz opening adjusted by a professional fabricator.

Use a carpenter’s square to check that the countertop cut-out is perfectly square. The sink rim must sit completely flat against the quartz.

Step 2: Install Mounting Brackets

Undermount sinks should always be supported by custom mounting brackets designed for quartz countertops. Position a bracket in each of the four corners of the sink cut-out. Make sure they are aligned and level.

Use a pencil to trace the outline of the brackets on the underside of the quartz. Remove the brackets and drill pilot holes for screws within the outline. Attach the brackets securely using the provided screws.

Step 3: Dry Fit the Sink

Carefully lower the sink into the opening to test the fit. Check the alignment along the countertop cut-out. Make sure the sink rim sits flush with no gaps or unevenness.

If you notice any imperfections in the fit, remove the sink and use a router to trim or smooth the edges of the quartz opening as needed. Safety glasses and gloves are a must for this step.

Step 4: Clean and Apply Adhesive

Thoroughly clean the bottom of the quartz counter and the rim of the sink with acetone or adhesive remover. This removes any dirt, oil or residue that could interfere with proper bonding. Wipe completely dry with a clean rag.

Apply a generous bead of silicone adhesive sealant around the top edge of the sink. Use an adhesive specifically designed for quartz and undermount sinks. Completely encircle the top of the sink with adhesive.

Step 5: Mount the Sink

Carefully lower the sink back into the opening in the quartz. Make sure to align it properly before the adhesive secures it in place.

From beneath the counter, gently press the sink rim upward to maximize contact with the adhesive and quartz. Securely tighten the mounting screws into the brackets. This will compress the silicone adhesive properly.

Step 6: Allow Adhesive to Cure

It is essential to let the silicone adhesive cure fully before using the sink. This usually takes about 24 hours. The bond will get stronger over the first 72 hours. Do not allow water to contact the silicone during this time.

After curing, inspect the seal and make sure there are no gaps or leaks between the sink and quartz. Tightly re-tighten the mounting screws if necessary.

Step 7: Make Water Supply Connections

Once fully cured, you can make the drain and water supply connections following the manufacturer’s instructions. It’s best to have hot and cold water lines installed by a professional plumber. Use high-quality braided steel lines for a long-lasting water connection.

Turn on the water supply and check for leaks. Tighten any fittings as required to stop dripping or seepage. Also, make sure the drain pipe has a proper downward slope for good drainage.

Tips for Success

Follow these tips to ensure a smooth installation:

  • Use custom sink-mounting brackets designed for undermount quartz installation.
  • Allow silicone adhesive to cure fully before using sink or disposing of scraps.
  • Make sure your quartz fabricator cuts an accurate opening for the sink.
  • Keep the sink rim and quartz contact edges completely clean before applying adhesive.
  • Apply silicone adhesive sealant evenly around the entire sink rim.
  • Tightly secure mounting screws into brackets beneath the countertop.
  • Avoid abrasive cleaners and stained sponges to prevent scratches.


What type of sink is best for a quartz countertop?

An undermount stainless steel or porcelain sink is recommended for quartz countertops. Avoid extremely heavy cast iron undermount sinks.

Can I install the sink myself or do I need a professional?

If you have DIY experience, you can install an undermount sink yourself by following the proper steps. No special qualifications are required.

What type of adhesive should be used?

Use a high-quality silicone adhesive sealant specifically designed for quartz and undermount sinks. Do not use standard silicone caulk.

How soon can I use the sink after installing it?

Allow the adhesive to cure completely, which generally takes about 24 hours. Wait 72 hours for maximum strength.

Does an undermount sink affect the durability of a quartz countertop?

No, installing the sink properly, without cracking the quartz, will not affect the durability or longevity of the countertop.

Can I cut the countertop myself or do I need it professionally done?

It’s best to have quartz countertops cut by a professional fabricator with the right tools and experience.


Installing an undermount sink in quartz countertops creates a high-end, seamless look. With careful planning, proper tools, and patience during installation, you can have a functional and beautiful undermount sink that will provide joy for years to come. Be sure to follow each preparation step, apply adhesive correctly, and allow full curing time.