How to Support Quartz Countertop Over Dishwasher

Assessing the Dishwasher and Countertop

  • Check the dimensions of the dishwasher opening to determine the span that needs support. Standard openings are about 24 inches wide.
  • Inspect the counter top and take note of the thickness. Quartz slabs are usually 3/4 inch thick.
  • Identify the type of quartz material and review manufacturer guidelines for overhang support. Some quartz formulations are more fragile than others.
  • Consider the design elements. Curved and angled edges or cutouts will need extra reinforcement.

Providing Adequate Support

Using a Bracket

  • A metal support bracket specifically designed for dishwasher tops is the easiest option.
  • Choose a bracket sized slightly smaller than the dishwasher opening. It should fit within the cavity.
  • Adjust the bracket height to align with the underside of the countertop. Secure it to the cabinetry with screws.
  • Test that the countertop rests flush and even on the bracket once installed. Add shims if needed.

Installing Cleats

  • Wooden cleats attached horizontally across the dishwasher opening also works.
  • Use 2×4 or 2×6 lumber. Cut cleats so multiple pieces evenly span the width.
  • Pre-drill and screw cleats into the cabinetry side walls to form a ledge for counter support.
  • Make sure cleats are level with each other and strong enough to bear the weight.

Using Support Bars

  • Iron support bars can be installed across the cavity opening like cleats.
  • Match the length to fit snugly across from side-to-side. Use at least two bars for widths over 12 inches.
  • Attach support bars securely into the cabinetry before setting the countertop.
  • Use shims to adjust the bars to all be level with the quartz underside.

Installing the Countertop

  • Carefully lower the quartz slab into place, centered on the dishwasher opening.
  • Verify that the countertop makes flush contact with the supports across the entire span.
  • Use a countertop adhesive like silicone to secure the quartz to the supports.
  • Allow the adhesive to fully cure before running the dishwasher.
  • Avoid placing excess weight on the unsupported section of countertop.

Preventative Measures

  • Check that cabinetry is reinforced and stable enough to bear the countertop load.
  • Use an anti-vibration pad under the dishwasher to reduce shaking that could cause cracks.
  • Allow a 1/8 inch gap between the countertop and dishwasher for expansion and contraction of the quartz slab.
  • Seal the seam with a flexible caulk to prevent moisture damage but allow slight movement.

Proper bracing and supports are critical to handle the overhang load and keep your beautiful quartz countertop securely in place above the dishwasher. With mindful installation methods, you can confidently enjoy an integrated look. Use these tips to install your countertop successfully!

Frequently Asked Questions

How much overhang can quartz support without brackets?

Most quartz countertops can only support an overhang up to 6 inches without brackets or other reinforcement. Anything beyond that will require supports.

What is the best adhesive to attach quartz to wood?

A flexible, waterproof adhesive like silicone is best to glue quartz to wood supports. This allows for expansion and contraction without cracking the rigid quartz.

Should you caulk between quartz countertop and dishwasher?

Yes, use a small bead of waterproof caulk to seal the seam between the countertop and dishwasher. This prevents moisture from penetrating behind and damaging the quartz or cabinetry.

How far apart should brackets be under an overhang?

A good rule of thumb is to place brackets or supports every 8-12 inches under a quartz overhang. Closer spacing is better to disperse the weight at regular intervals.

Can you use granite brackets for quartz?

Yes, brackets made for granite countertops will also work for quartz. Just ensure the size fits the dishwasher opening and adequately supports the span.

What kind of wood can support a quartz countertop?

Plywood, LVL beams, 2×4 or 2×6 dimensional lumber are all good wood choices to create supports under a quartz overhang. Opt for vertical grain fir or redwood for best strength.

Should you reinforce quartz near a cutout?

It’s wise to add extra brackets or supports near any cutouts or notches in a quartz countertop. This minimizes stress concentrations at the weaker sections near holes.


Installing quartz over your dishwasher provides a streamlined, modern look. With proper planning and bracing, you can successfully support the overhang while avoiding unsightly cracks. Measure carefully, install sturdy supports at frequent intervals, and allow slight movement at seams. Follow these best practices for hassle-free integration of your beautiful quartz countertop and dishwasher.