How to Install a Dishwasher Under a Quartz Countertop

Installing a dishwasher under a quartz countertop requires careful planning and execution to ensure proper clearance, drainage, and functionality. Quartz is an extremely durable engineered stone, but it still requires special care during installation to avoid cracking or chipping. With some advance preparations and the right techniques, you can successfully install a dishwasher without damaging the countertop.

Gather Materials and Tools

Before starting any work, gather all the materials and tools you will need:

  • Dishwasher
  • Water supply line
  • Drain hose
  • Electrical cable
  • Mounting brackets and hardware
  • Drill and drill bits
  • Level
  • Protective materials like painters tape and cardboard
  • Silicone caulk
  • Screwdrivers
  • Wrenches
  • Teflon tape
  • Pipe clamps

Make sure you have everything readily available to streamline the installation process. You may need additional supplies like wiring nuts or plumbing fittings depending on your specific setup.

Prepare the Cabinet

Start by thoroughly cleaning out the area under the quartz countertop and remove any shelving or drawers where the dishwasher will go. This gives you ample room to maneuver and install the appliance.

Examine the floor of the cabinet for levelness. Any uneven spots greater than 1/8″ should be corrected with shims to prevent rocking of the installed dishwasher. Ensure the cabinet floor is sturdy enough to hold the weight of a full dishwasher.

Use a stud finder to locate and mark the positions of studs on the sides and back wall of the cabinet. You will need to anchor the mounting brackets to the studs for maximum stability.

Install Mounting Brackets

Following the instructions provided with your dishwasher, attach the mounting brackets securely to the studs at the appropriate height. Make sure the brackets are perfectly level. Test fit the dishwasher into the cabinet to verify it slides smoothly into place.

If needed, adjust the mounting brackets so the top of the dishwasher lines up evenly with the underside of the countertop. There should be no more than a 1/4″ gap.

Prepare Countertop and Make Cutout

Protect the quartz countertop surface with painters tape and cardboard before making any cutouts. Measure and mark the width and depth of the dishwasher according to the manufacturer’s specifications for an accurate cutout size.

Carefully cut out the opening using a jigsaw with a diamond grit blade and water feed attachment to control overheating. Take it slowly and make relief cuts at all corners to avoid cracking or chipping the quartz. Smooth any rough edges with sandpaper.

Thoroughly vacuum and clean the cutout area to remove debris before proceeding.

Hook Up Plumbing and Electrical

Attach the dishwasher’s water supply line to the shutoff valve under the sink, using pipe clamps for a tight connection. Extend the electrical cable through the cabinet wall and connect it to the junction box according to appliance instructions, securing with a cable clamp.

For drainage, connect the drain hose to the sink tailpiece or garbage disposal using the included hose clamp. Make sure there are no kinks and the hose has a high loop for proper water flow. Test for leaks once all connections are made.

Install Dishwasher Under Countertop

Place protective cardboard over the countertop surface around the cutout before fitting the dishwasher into place. Slowly slide the appliance into the cabinet opening, aligning its top front edge with the countertop. Do not lift or force the dishwasher from underneath to avoid damaging the quartz.

Confirm the dishwasher is centered, level, and flush with the cabinet front. Securely fasten it to the mounting brackets underneath. Open and close the door to check for proper clearance with no rubbing or scraping against the countertop.

Apply Silicone Sealant

Run a continuous bead of moisture-cure silicone caulk around the gap between the dishwasher top and quartz countertop. Carefully smooth the caulk with a wet finger for a neat finish. Remove any excess caulk right away. Allow the sealant to fully cure for at least 24 hours before running the dishwasher.

The key steps are taking precautions when cutting the countertop, properly anchoring the dishwasher, and sealing around the edges. With careful installation, you can enjoy trouble-free use of an under-counter dishwasher with a beautiful quartz countertop.

Frequently Asked Questions

What size hole do I cut for an undermount dishwasher?

The cutout size depends on your specific dishwasher model, but is typically about 24 inches wide by 24 inches deep. Refer to the manufacturer’s instructions for the exact dimensions.

How close can my dishwasher be to the sink?

It’s recommended to allow at least 4 inches between the dishwasher and sink or range for clearance. Check your dishwasher manual for the minimum spacing allowed.

Should I seal a quartz countertop to the dishwasher?

Yes, use a bead of silicone caulk to seal the gap between the dishwasher top and quartz countertop. This prevents moisture damage.

What do I do if my countertop cracks during cutting?

Stop cutting and use cyanoacrylate adhesive to repair minor cracks. For larger cracks, consult a countertop professional about removing and replacing that section of quartz.

How do I secure the dishwasher to the cabinet?

Use mounting brackets screwed into the cabinet walls studs, then secure the dishwasher to the brackets with screws once it is aligned under the countertop.


Installing a dishwasher under quartz requires careful measurements, proper drainage setup, secure mounting, and silicone sealing. Always use caution when cutting the countertop and work slowly to get a clean opening without cracks or chips. With good planning and the right techniques, you can have an integrated dishwasher that seamlessly fits your quartz countertop. Refer to the manufacturer’s guide and don’t rush the process. Taking your time will lead to a successful installation that looks great and functions flawlessly.