How to Level Old Cabinets for Quartz Countertops

Introduction to Leveling Cabinets for Quartz Countertops

Quartz countertops can provide a beautiful, durable, and low-maintenance surface for kitchens and bathrooms. However, proper installation is key to ensuring these countertops function properly and look their best. One important aspect of installation is making sure the cabinets are completely level before setting the quartz slabs. Old cabinets may have settled or shifted over time and no longer be perfectly plumb. Taking the time to level them allows the countertop to sit flat and prevents cracking or chipping on the edges from stress. The process involves checking for level, identifying high and low spots, and using shims or washers to bring the cabinets into a perfect plane. With some careful preparation, you can have your new quartz countertops installed securely on leveled cabinets.

Tools and Materials Needed

Leveling cabinets requires just a few simple tools and materials:

  • Spirit level – An essential tool for identifying high and low spots. Use a long level that can span the entire cabinet run.
  • Shims – Small wooden wedges available in different thickness that can fill gaps under cabinets. They come in packs for purchase.
  • Washers – Standard washers in varying sizes can work as shims. Stack to adjust height.
  • Wood glue – To secure shims in place once level is achieved.
  • Sandpaper – Helpful for smoothing and fitting shims. Higher grit removes less material.
  • Drill – For drilling holes to secure shims in place after gluing.
  • Screws – To reinforce shims and hold level position permanently.

Having these basic supplies on hand will make leveling old cabinets much simpler. Check that the level itself is accurate before getting started.

Steps to Level Kitchen Cabinets for Quartz Countertops

With the right tools at the ready, the process for leveling cabinets can begin. Follow these key steps:

1. Check for Level Across All Cabinets

First, examine the entire span of cabinets using a long spirit level. Place the level horizontally across the tops of the cabinet boxes, testing the front-to-back level. Mark any areas that are higher or lower than the level plane. Also check levels from side-to-side. Identify all uneven areas to be addressed.

2. Use Shim Thickness to Fill Low Spots

After thoroughly checking and marking any uneven areas, determine how much of a gap exists in the low spots. This will indicate what thickness of shim is needed. For very thin gaps, a single washer may do. For larger gaps, stack combinations of washers and use thicker shim boards.

3. Cut and Sand Shims to Fit

Carefully cut and sand shims to fit into the gap areas snugly. Test fit and make any adjustments for smooth sliding into place with no major high or low edges. Use higher grit sandpaper when fitting to avoid removing too much material.

4. Glue Shims In Place Under Cabinets

Run a bead of wood glue along the top edge of the shims. Insert into the gaps beneath the low end of the cabinets, aligning the tops flush in a level plane. Allow the glue to dry fully.

5. Secure With Screws

For permanent reinforcement, use a drill to make pilot holes and insert wood screws into the shims anchoring them to the cabinet base. This keeps them solidly in position.

6. Re-check Levels and Make Any Final Adjustments

Examine the results and re-check for level across all cabinets with a long spirit level. Add any final thin shims or washers needed to achieve perfectly level alignment along the entire top surface.

Once the steps are complete, you can have peace of mind that the cabinets are ready for quartz countertop installation. Taking the time to properly level provides the flat, stable surface quartz requires to prevent cracking and perform beautifully.

Frequently Asked Questions

How much gap or slope can be shimmed for leveling?

In general, small gaps of 1/8 inch or less can be leveled with shims without difficulty. If cabinet bases have large gaps of more than 1/4 inch, addressing the underlying support structure may be needed.

What areas should be checked?

Check the entire span of counter area by placing levels diagonally and horizontally across cabinet tops and bases. Also check from front to back and side to side.

Should anything be done to shims before installing them?

Sanding shims helps create flush edges and smooth fits. Also run a bead of wood glue along the top edge before sliding into place for better adhesion when setting.

Can self-leveling compound be used instead of shims?

Pouring self-leveling compound offers an alternative, but does not provide as solid a base as shimming. It also adds height you may not want for countertop clearances.

Is it okay to stack multiple shims or washers?

Yes, stacking combinations of washers and shims allows you to achieve just the right amount of height adjustment in uneven spots.


Leveling old cabinets takes time and care, but is a key step before quartz countertop installation. By using an accurate spirit level, cutting and fitting shims to fill low spots, gluing them securely in place, and drilling screws to reinforce, you can achieve a perfectly flat and stable surface for your new quartz countertop. Taking the effort to properly level cabinets prevents costly damage and ensures your beautiful new quartz countertop looks amazing for years to come. With some patience and the right technique, you can have peace of mind knowing your cabinets provide full support.