How to Level Quartz Countertop

Assessing the Existing Countertop

Before installing the new quartz countertop, you’ll want to assess the existing countertop and ensure the base cabinets are level. Here are a few tips:

  • Clear everything off the countertop and cabinets so you have a clear workspace.
  • Use a level tool on the existing countertop to identify any uneven spots. Mark any high or low spots.
  • Check that the base cabinets are level front to back and side to side. Shim any cabinets that are unleveled.
  • Look for any damage, rot, or other issues with the base cabinets that need to be addressed prior to installing the new top.

Addressing any underlying issues with the cabinetry is an important first step to ensuring your new quartz countertop will install evenly.

Gather the Necessary Materials

Installing and leveling a quartz countertop requires just a few specialized materials and tools:

  • Quartz slabs
  • Thin-set mortar adhesive
  • Trowel for applying mortar
  • Shim kits or washers for leveling
  • Level tool (4-foot level recommended)
  • Brackets to support overhangs
  • Color-matched caulk
  • Denatured alcohol to clean quartz

Be sure to have all materials on hand before beginning the installation process.

Clean the Cabinets

Once the existing countertop is removed, thoroughly clean the base cabinets. Remove any old adhesive, grease, dust, or debris.

Proper cleaning will allow the thin-set mortar to adhere tightly to the cabinet bases. Be sure the cabinets are completely dry before applying mortar.

Apply the Mortar

Follow the mortar adhesive manufacturer’s recommendations for application. In general:

  • Apply a generous layer of thin-set mortar to the tops of the cabinets using a notched trowel.
  • Spread the mortar evenly across the cabinets, using the trowel notches to create ridges.
  • Pay special attention to spreading mortar at the edges and corners.
  • Only apply as much mortar as can be covered by the quartz slabs within about 10 minutes.

The mortar layer needs to be thick enough to support and level the full surface area of the countertop.

Set Quartz Slabs in Place

Once the mortar is prepared, carefully lower the quartz slabs into place:

  • Lift each slab with a helper or lifting device. Do not let the bottom touch the floor once mortar is applied.
  • Gently set slabs into the mortar, pressing down firmly to ensure even contact.
  • Check for level on the slab surface as you set it into place. Make any necessary adjustments.
  • Use shims between the cabinet and slabs if any areas are uneven. This will level as mortar cures.
  • Wipe away excess mortar squeeze-out using a damp cloth.

Be extremely careful when lifting and placing the quartz slabs to avoid cracks and breaks. Take your time to position properly.

Allow Mortar to Cure

Once all slabs are set into the mortar, allow everything to cure according to manufacturer recommendations. This is usually 24-48 hours.

  • Do not disturb the countertop while mortar is curing.
  • Keep the area clean and dry during the curing period.
  • Remove shims only after the mortar has fully cured.

Proper curing time ensures a strong, level bond between the quartz and cabinet base.

Complete the Installation

After curing, complete the quartz countertop installation:

  • Clean quartz surfaces with denatured alcohol and let dry completely.
  • Apply a matching colored caulk to all seams and joints. Allow caulking to dry completely.
  • Attach any brackets or supports for overhangs as needed.
  • Seal where the countertop meets walls, sinks, or other fixtures.

Take care of any final details for a seamless installation. Now you can enjoy your perfectly level, functional, and beautiful new quartz countertop!

FAQs About Leveling Quartz Countertops

How thick should the mortar layer be under a quartz countertop?

The mortar layer should be at least 1/4-inch thick after setting the slabs. Thicker layers up to 1/2-inch are acceptable if needed to level the surface.

What is the best way to transport quartz slabs?

Carefully transport slabs upright and avoid letting the bottom edge contact the floor once mortar is applied. Use an A-frame, straps, or lifters designed for heavy stone.

Can I install the countertop directly onto the cabinets without mortar?

Mortar adhesive is strongly recommended. It allows leveling uneven cabinets and provides a much stronger bond. Self-adhesive countertops tend to fail over time.

How long does quartz countertop mortar take to cure?

Most mortar adhesives designed for quartz countertops take 24-48 hours to fully cure. Do not use the countertop until completely cured.

What do I do if my countertop is uneven after installing quartz?

First ensure the mortar has cured completely. Then you can remove and shim uneven areas as needed. Avoid trying to re-level too soon while mortar is still damp.


Installing a quartz countertop provides a gorgeous, functional surface when done properly. Taking the time to ensure an even, level installation will keep your countertop looking pristine for decades. Prepare the base cabinets, use quality materials, and allow proper curing time. With some patience and attention to detail, you can level a quartz countertop for optimal performance.