How to Undermount Sink with Quartz Countertops


Installing an undermount sink with quartz countertops can add a sleek, modern look to your kitchen. Quartz is an engineered stone that is very durable, low maintenance, and resistant to scratches, stains, and heat. Undermount sinks create a seamless transition from the countertop to the sink bowl for easy cleaning.

When paired together, an undermount sink and quartz countertop make a stylish statement. But proper installation is key to get that flawless look. There are several steps involved in how to undermount sink with quartz countertops. This article will walk you through the entire process.

Selecting the Right Sink and Countertop

The first step is choosing the right sink and countertop for your space.

Sink Material Options

Undermount sinks commonly come in:

  • Stainless steel – Most popular option. Durable, affordable, easy to clean, and pairs well with quartz. Choose a thick 18 or 20 gauge stainless steel sink for best quality.
  • Enameled cast iron – Classic look. More prone to chipping than stainless steel. White and black are popular color choices.
  • Composite – Made from mix of acrylic resins and crushed stone. Affordable, scratch-resistant, and available in range of colors.
  • Copper – Gorgeous look but requires frequent polishing to maintain shine. Generally more expensive.
  • Fireclay – Made from ceramic material. Chips and stains more easily than other materials.

Quartz Countertop Styles

When selecting a quartz countertop, consider:

  • Color – Quartz comes in a wide variety of colors and patterns. Pick one that pairs well with your sink and cabinetry.
  • Thickness – Thicker quartz of 2 to 3 cm is best for undermount sink installation. Provides needed support.
  • Perimeter – Make sure the countertop has enough perimeter space for the sink, faucet, and any accessories.
  • Cut-Out – Have the sink cut-out done by fabricator when they template. This ensures a precise fit.

Make sure to select coordinated styles and finishes for your sink and countertop. The combo should align with the overall design of your kitchen.

Prepare the Cabinet and Counter Area

Once you’ve selected the sink and countertop, next get the cabinet and countertop areas prepped. This involves:

Remove Existing Countertop

If there is an old countertop already in place, carefully remove it using a circular saw and reciprocating saw to free it from the cabinet.

  • Make clean cuts around any sink holes or glue lines
  • Remove in sections if needed
  • Wear safety goggles and mask to avoid dust inhalation

Clean any old adhesive, sealant, or debris off of the cabinet once the old countertop is removed.

Replace Damaged Cabinets

Inspect cabinets for any water damage or deterioration. Make any needed repairs or replacements before installing new countertop.

Adjust Cabinet Supports

The cabinet base must be sturdy enough to hold the weight of the quartz countertop and sink. Add additional supports or plywood if needed.

Fill Gap at Wall

Seal any gaps between the cabinet and wall with caulk or foam insulation strips. This prevents moisture and pests from getting in.

Prepping the cabinets and countertop area well will ensure your new materials install securely.

Prepare Sink Base Cabinet

The sink base cabinet needs some special modifications to properly hold an undermount sink.

Cut Out Front Panel

Using a jigsaw, cut out the front panel of the sink base cabinet to expose the sink location. Cut 3 inches larger than sink dimensions.

Install Support Bracing

Attach 2×4 bracing lumber inside the sink base cabinet walls using wood screws. This provides added reinforcement for the sink weight.

Make Plumbing Adjustments

Adjust drain and supply lines as needed to align with the new undermount sink location. May require hiring a plumber.

Build Custom Sink Frame

Construct a sturdy sink frame out of 2×4 lumber that sits inside the sink base cabinet. This provides a solid surface to mount the sink to.

Waterproof Inside of Cabinet

Line the inside of cabinet with plastic sheeting. Apply heavy duty construction adhesive or silicone caulk to hold in place. This prevents moisture damage.

Preparing the sink base cabinet properly is a crucial step in how to undermount sink with quartz countertops. It provides needed support.

Prepare and Install the Countertop

Now for the countertop preparation and installation. Proper techniques will ensure a secure and seamless installation.

Clean Mounting Surface

Use denatured alcohol to fully clean and sanitize the surface of the cabinets where the countertop will be installed. Remove any grease, dirt, or debris.

Apply Adhesive

Run a continuous bead of construction adhesive along the top edges of the cabinet. Use enough to fully seal once countertop is set in place.

Set Countertop in Place

Carefully lift and position the quartz countertop over the cabinets. Have helpers to hold the heavy countertop in place.

Apply Support Braces

Place wood brackets tightly in the corners and tight to the bottom of the countertop. This provides support as adhesive dries.

Remove Excess Adhesive

Use a putty knife to remove any adhesive squeeze-out. Quickly wipe away excess before it dries. Avoid getting it on the visible areas of the quartz.

Allow Proper Cure Time

Leave countertop undisturbed while the adhesive fully cures. This often takes 24 hours. Consult adhesive instructions.

Proper countertop installation avoids movement, lifting, or cracking later on. Take the time to do it right.

Cut Sink Hole in Quartz Countertop

Now comes the tricky part – cutting the sink hole in the quartz countertop. This requires precision and the right tools.

Mark Cut Lines

Use the sink itself upside down on the countertop to trace cut lines. Leave small gap between sink edge and lines.

Set Cut Depth

Adjust blade depth on circular saw to be just slightly deeper than countertop thickness. Prevent cutting into cabinets.

Drill Holes at Corners

Drill 1 inch holes at each corner point. This allows space for the saw blade to cut through.

Make Cut-Out

Use a specialized quartz-cutting circular saw to cut along the marked sink outline. Take it slow. Keep spray bottle handy to minimize heat and dust.

Smooth Edges

Use a file and sandpaper to smooth down and round the cut edges so there are no sharp corners.

Clean Up Dust

Carefully vacuum up all quartz dust and fragments around the sink hole. Quartz particles are harmful if inhaled.

Cutting the countertop hole is a very delicate process. Take all safety precautions and go slowly to get it right.

Mount the Undermount Sink

Now the sink can be successfully mounted to your quartz countertop. Proper mounting is crucial for functionality and aesthetics.

Set Sink in Place

Turn sink over and carefully lower into the pre-cut countertop hole. Center evenly.

Apply Sealant

Run a continuous thick bead of silicone adhesive sealant around sink edge. Use enough to make full contact with countertop.

Attach Mounting Clips

Place the provided metal mounting clips evenly spaced around the sink. Tighten their set screws against the countertop underside.

Allow Sealant to Cure

Let the silicone adhesive fully cure and harden before using sink. This often takes 24 hours. Avoid any water contact during this time.

Make Drain Connections

Connect sink drain assembly tailpiece, P-trap, and drain pipes. Check for leaks and make any needed adjustments.

With good sealant coverage and secure mounting clips, your undermount sink will have a solid attachment to your quartz countertop.

Make Faucet and Plumbing Connections

Finish up the job by connecting the faucet and water supply lines to the new sink.

Install Faucet

Place faucet through appropriate holes in sink or countertop. Position, align, and secure into place with mounting nuts underneath.

Connect Water Supply Lines

Attach flexible braided steel supply lines from shut-off valves to faucet inlets. Use proper fittings and tighten securely.

Check for Leaks

Turn on water supply and test faucet and drain connections. Tighten any areas that drip or leak water.

Caulk around Faucet

Apply a steady bead of silicone caulk around edges of faucet where it contacts the countertop. Allow to dry before use.

With the faucet installed and connected properly, you can now use your stylish new undermount sink!

Tips for Maintaining Undermount Sink with Quartz

Follow these tips to keep your undermount sink and quartz countertop looking like new for years:

  • Use non-abrasive cleansers to avoid dulling or etching the finishes
  • Use a silicone-based polish regularly on the sink to maintain luster
  • Seal quartz annually and re-caulk when needed to prevent moisture issues
  • Use trivets or hot pads under hot pans and pots to prevent burns
  • Avoid harsh drain cleaners which can damage sink and drain pipes
  • Wipe up spills immediately to keep quartz stain-free
  • Run water when pouring harsh chemicals like bleach to prevent accumulation

Proper daily care will maintain the sleek beauty of your undermount sink and quartz countertop installation. Follow the steps above on how to undermount sink with quartz countertops for best results.

Frequently Asked Questions about Undermount Sinks with Quartz Countertops

Can you put an undermount sink in a quartz countertop?

Yes, undermount sinks are commonly installed in quartz countertops. The sink edge sits below the countertop for a seamless appearance. Proper installation technique is key though to create a strong, water-tight connection.

Do undermount sinks work with all thicknesses of quartz?

For best support, the quartz thickness should be at least 2 cm for undermount sinks. Thinner quartz may allow the sink to flex or warp over time under its weight. Go with thick 3 cm quartz if possible.

What problems occur from improper undermount sink installation?

If the sink isn’t properly supported or mounted, it can come loose and leak. Cracks may also form around the sink edge if it isn’t secured evenly. Use plenty of high-quality silicone sealant and secure mounting brackets.

Can you install undermount sink yourself or need a pro?

It’s possible for a DIYer to install undermount sink in quartz, but it’s a very tricky job. Small mistakes in cutting the hole or mount sink can lead to big problems later. Consider hiring a pro if you lack experience.

What’s the average cost to install undermount sink in quartz?

The typical price range to install an undermount sink in a quartz countertop is $200 – $500, including labor and materials. Complex installations with drain or plumbing work cost more. Shop around for best value.

How long does it take to install undermount sink in quartz?

If done properly, expect the undermount sink installation in quartz to take 2-3 days from start to finish. Time is needed for careful cut-out, proper sealant curing, plumbing connections, and testing for leaks before use.

Should anything be sealed between sink and quartz?

Yes, use a premium silicone sealant between the sink and quartz countertop. This fills any small gaps and prevents water from getting in and damaging cabinets. Sealant provides added bonding strength.


Installing an undermount sink paired with quartz countertop can create a high-end, contemporary look in your kitchen. By following the techniques described above on how to undermount sink with quartz countertops, you can achieve a flawless finished look. Pay close attention to proper support, mounting, and sealing methods. Take precautions when cutting the quartz to avoid mistakes. With some patience, the right materials, and proper methods, you can successfully install an undermount sink in quartz countertops.