How to Shim Quartz Countertops

Quartz countertops are popular options for kitchens and bathrooms due to their durability, aesthetic appeal, and low maintenance. However, like any solid surface countertop, quartz can develop low spots or become uneven over time. Proper shimming is key to keeping your quartz countertops looking and functioning their best. Here is a comprehensive guide on how to shim quartz countertops.

What is Shimming and Why it’s Necessary for Quartz Countertops

Shimming refers to the process of leveling countertops by placing shims, or thin wedges, beneath the countertop surface. This is done whenever the countertop develops dips, slopes, or unevenness that can lead to rocking, wobbling, or other issues.

There are a few reasons why quartz countertops may require shimming:

  • Settling of cabinets or uneven floors over time
  • Improper installation where countertops were not adequately leveled and supported
  • Warping due to excessive heat, weight, or moisture exposure

If your quartz countertop has developed low spots greater than 1/8 inch across a 10-foot span, it likely needs to be re-leveled through shimming. Addressing unevenness ensures functionality and prevents further warping or cracking long-term.

Preparing for Shimming Quartz Countertops

Shimming quartz requires patience and proper preparation for best results:

Clean Countertop

Clear the countertop of any items, debris, or spills. This allows you to see the overall topography and identify problem areas. Clean the surface so shims properly adhere.

Gather Supplies

You will need shims, construction adhesive, a putty knife, ruler, pencil, and rags. Use wedge shims made from plastic or wood. Acquire shims of varying thickness to account for minor and major uneven spots.

Locate Low Spots

Use a straightedge such as a ruler or level to identify dips and gaps. Look along the length and depth of countertops to pinpoint where shimming is needed. Mark low spots with a pencil.

Disconnect Sink/Faucet

Removing any installed sinks or faucets provides full access for shimming. Turn off water supply lines and disconnect drain pipes before lifting sink away from the countertop.

How to Shim a Quartz Countertop

Once you have prepared your workspace and materials, you can begin shimming the quartz:

  1. Lift Countertop Edge – Carefully lift the countertop edge just enough to slide shims underneath. You may need a partner to help with safe lifting.
  2. Insert Shim – Use a putty knife to apply construction adhesive to the shim. Slide shim fully under countertop in the marked low spot.
  3. Check Level – Set countertop back down gently and use a straightedge to check level. Target 1/8 inch height gaps or less for best support.
  4. Repeat as Needed – Lift, shim, and level across all identified low spots until the countertop is even. Let adhesive fully cure before use.
  5. Reinstall Sink/Faucet – With the countertop now shimmed and leveled, reinstall any sinks, faucets, soap dispensers secured to it.

Tips for Successful Quartz Countertop Shimming

Follow these tips for optimal and safe shimming results:

  • Work slowly and cautiously when lifting to prevent cracking or breaking.
  • Use larger shims to fill bigger gaps rather than stacking many shims.
  • Make sure shims are fully adhered with adhesive before setting down.
  • A 1/8 inch level variation or less across the whole countertop is ideal.
  • Allow construction adhesive to fully cure for 24-48 hours before regular use.
  • Add waterproofing along seams or edges after shimming for added protection.
  • Retest for levelness after a few days and re-shim any new low spots that appear.

Common Mistakes to Avoid

Steer clear of these errors when shimming quartz:

  • Not fully cleaning and prepping the underside before shimming
  • Using makeshift items like matchsticks or folded paper instead of proper shims
  • Failing to disconnect sinks, faucets, or cooktops before lifting the countertop
  • Putting excessive pressure on one area when lifting the quartz top
  • Allowing gaps larger than 1/8 inch between shims and quartz surface
  • Neglecting to use enough adhesive for shims to stay in place
  • Not letting the adhesive cure per the manufacturer’s recommendations
  • Skipping re-checks for levelness in the following days

When to Call a Professional

If your quartz countertop has major unevenness beyond 1/4 inch, call a professional fabricator. Severe gaps or repeated shimming issues may indicate a flawed install. Professionals have the tools, adhesives, and experience for quartz shimming not achievable by DIY methods.

Frequently Asked Questions About Shim Quartz Countertops

What are the signs my quartz countertop needs shimming?

Look for obvious slope, rocking back-and-forth when applying pressure, items rolling down the surface, visible gaps between the counters and walls, pooling of water, or difficulty sliding items from one end to the other.

How can I prevent my quartz from needing shims in the future?

Avoid excessive heat exposure, use trivets and hot pads, clean spills quickly to prevent moisture damage, and don’t place excessive weight in one area. Annual checks for levelness are also a good preventative measure.

Is shimming quartz countertops a DIY job?

With proper materials and patience, most homeowners can successfully shim their own quartz. But if you don’t feel comfortable lifting and maneuvering the countertop, its best to hire a professional installer.

What thickness of shims should I use for quartz?

For minor dips, plastic shims from 1/16 inch to 1/8 inch thickness are sufficient. For gaps 1/4 inch or more, use thicker hardwood shims to prevent stacking many thin shims.

Will I need to completely remove the quartz countertops for shimming?

In most cases, no. The countertop can be partially lifted just enough to slide shims underneath as long as cabinets or walls don’t obstruct access. Complete removal increases the installation work.


With some careful prep work and the right techniques, shimming a quartz countertop is an achievable DIY project. Pay attention to fully leveling all low spots and allowing adhesives to cure properly. Take your time lifting and working the quartz carefully to prevent damages. Shimmed properly, your countertops will once again be strong, stable and perfectly level for daily use and enjoyment.