How to Install an Undermount Sink in Quartz Countertop

Installing an undermount sink in a quartz countertop can seem daunting, but with proper planning and execution, 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 create a seamless transition between the sink and the countertop for a clean, modern look. The sink drops into a hole cut into the countertop and is mounted underneath, out of view. Quartz makes an excellent countertop material for undermount sinks because it is nonporous, stain-resistant, and durable. With proper installation, an undermount sink and quartz countertop can last for decades.

Benefits of Undermount Sinks in Quartz

  • Smooth transition between sink and countertop.
  • Easier to wipe water and debris into the sink.
  • No cracks or seams to collect gunk.
  • Elegant, modern look.
  • Quartz is tough and retains its luster over time.

Steps to Install an Undermount Sink in Quartz

Gather Supplies

You will need:

  • Undermount sink
  • Quartz countertop
  • Silicone caulk
  • Caulk gun
  • Brackets and hardware for sink
  • Power drill and bits
  • Silicone sealant safe for quartz
  • Pipe wrenches
  • Plumbers putty
  • Jigsaw with diamond or stone blade

Prepare the Countertop

  1. Measure the sink and mark the cutout area on the underside of the quartz countertop. Account for any overhang into the cabinet.
  2. Drill a pilot hole inside the cutout area. Use a jigsaw with a diamond or stone blade to cut the sink opening. Make rounded corners to prevent cracking.
  3. Check that the sink fits correctly in the hole. Use sandpaper to smooth any rough edges.

Install the Sink

  1. Set the sink in place and mark the mounting holes. Drill pilot holes for the mounting hardware.
  2. Apply a bead of silicone caulk around the edge of the sink. Place the sink in position and attach the mounting brackets below the countertop.
  3. Tighten the mounting hardware evenly to secure the sink. Don’t overtighten!
  4. Apply silicone sealant where the sink meets the countertop. Smooth the bead with a spatula for a neat finish.
  5. Allow the caulk to cure completely before using the sink, usually 24-48 hours.

Hook Up the Plumbing

  1. Disconnect the drain pipe and p-trap under the old sink.
  2. Apply plumber’s putty around the new drain hole and attach the drain assembly. Tighten the locknut below.
  3. Connect the p-trap and drain pipes to the sink tailpiece. Use pipe wrenches to tighten joints.
  4. Attach the faucet and supply lines according to manufacturer instructions.
  5. Run water into the sink and check for leaks. Tighten any joints if necessary.

Tips for Installing an Undermount Sink in Quartz

  • Use painter’s tape around the cutout area to prevent damaging the quartz surface.
  • Take time to get the sink placement right. Once installed, the sink can be difficult to remove.
  • Clean up any silicone, plumber’s putty, or adhesive before it dries. Acetone can help remove residue.
  • Avoid putting excess strain on the sink and countertop. Store heavy items elsewhere.
  • Use a waterproof silicone sealant designed for use with quartz around the sink perimeter.
  • Get help lifting the quartz countertop if needed. Hire a professional installer if uncomfortable doing this yourself.

With proper tools, patience, and attention to detail, installing an undermount sink in quartz countertops can create a high-end, seamless look in your kitchen or bath. Follow the techniques outlined above for a smooth installation. Take care not to rush the process – a careful DIY approach will pay off with a stunning, durable finished product.

Frequently Asked Questions

What type of sink should I use with a quartz countertop?

For quartz countertops, an undermount sink is recommended as it creates a continuous flow into the sink area. Stainless steel or porcelain undermount sinks pair well with quartz.

How much support is needed under a quartz sink cutout?

Quartz does not usually need additional bracing under a sink cutout if it is at least 3 cm thick. Always have solid cabinet support below the cutout area.

What mistakes should be avoided when installing an undermount sink?

Avoid overtightening the mounting hardware or putting undue strain on the sink and countertop. Take time to precisely measure and cut the countertop opening for the snuggest fit. Also, use a sink-specific silicone sealant to prevent water damage.

Should the sink be installed before or after the countertop?

For undermount sinks, it is easier to install the countertop first and then cut the hole for the sink. This allows precise measurements and alignments.

How long does silicone need to cure before using the sink?

Most silicone sealants take 24-48 hours to fully cure. Avoid putting any strain on the sink during this time. After 48 hours, the sealant should be water-ready.


Installing an undermount sink in quartz countertops upgrades your kitchen with a high-end, contemporary look. With proper planning and careful technique, this is a DIY project suitable for an intermediate to advanced homeowner. Gather all necessary supplies and tools beforehand. Measure twice and cut accurately. Allow adequate curing time for caulk and sealant to prevent leaks or damage. With patience and care, you can enjoy a seamless, stylish undermount sink in your beautiful quartz countertop.