7 Best Steel Shims for Leveling Cabinets That Last

A wobbly cabinet or a countertop that sits unevenly can turn a simple kitchen task into a source of daily frustration. While many reach for folded cardboard or plastic wedges to bridge the gap, these materials often compress or rot over time, leading to recurring maintenance. Investing in steel shims provides a permanent, load-bearing solution that ensures cabinetry stays perfectly plumb for years to come.

Precision Brand Slotted Shims: Best Overall Pick

When professional cabinet installers need a solution that won’t budge, they often reach for slotted steel shims. These are designed with a U-shaped cutout that allows them to slide easily over existing bolts or screws without the need for full disassembly.

The precision-stamped thickness ensures consistency across every corner of the cabinet carcass. Because these are made from high-quality cold-rolled steel, they offer unmatched durability for heavy granite or quartz countertops.

For the homeowner looking for a “set it and forget it” solution, these are the gold standard. While they carry a higher price point than plastic alternatives, the peace of mind of having a truly level cabinet installation is worth the investment.

Big Horn Steel Shim Set: Best Value Assortment

Large cabinetry projects, such as installing a full run of kitchen uppers, often require varying thicknesses to account for uneven walls and sagging floors. The Big Horn set provides a variety of gauges in one convenient package, eliminating the need to guess the exact gap size beforehand.

This assortment is perfect for the DIYer who wants to keep a stash in the workshop for occasional repairs or future renovations. Having a range of thicknesses at the ready prevents the need for multiple trips to the hardware store when a single thickness doesn’t quite get the cabinet level.

The value here lies in the versatility of the kit. It covers the most common alignment issues found in older homes where square corners are rarely guaranteed.

Everbilt Steel Shim Pack: The Hardware Store Go-To

For a quick repair on a single cabinet base or a vanity that has developed a slight tilt, individual packs from a local hardware store are often the most practical choice. Everbilt products are widely available and offer a reliable, no-nonsense metal shim for basic leveling tasks.

These are best suited for smaller household projects where the specific gap is already known and a full, expensive set is unnecessary. They provide the necessary steel strength to prevent sink cabinets from shifting under the weight of porcelain or heavy stone basins.

While they may lack the extensive variety of specialty kits, they excel in accessibility. If a homeowner discovers an uneven cabinet during a Saturday project, these shims provide an immediate, sturdy fix.

Grade 8 Steel Shims: For Your Heaviest Cabinets

Some cabinets, particularly those housing heavy dinnerware or acting as a base for custom concrete countertops, require extreme compression resistance. Grade 8 steel shims are crafted from high-tensile material designed to withstand intense loads without deforming.

These are not intended for minor alignment tweaks, but rather for structural support in demanding areas. If a cabinet feels “spongy” when weight is applied, Grade 8 shims will hold their shape indefinitely, preventing the slow creep that occurs with weaker materials.

Homeowners should consider these only when the cabinet weight exceeds the capacity of standard mild steel. They represent the strongest option available for ensuring structural integrity in high-traffic kitchens.

Precision Brand Shim Stock Roll: Cut Any Size You Need

Sometimes, a cabinet frame rests against a wall with an irregular gap that doesn’t fit standard rectangular shims. A roll of shim stock allows the user to cut custom lengths and widths to match the exact profile of the cabinet edge.

This is a favorite among detail-oriented homeowners working in older homes with wavy plaster or drywall. By trimming the metal with heavy-duty shears, one can create a perfect, custom fit that is virtually invisible once the trim is applied.

While this requires more labor than using pre-cut shims, the result is a clean, professional finish. It is an excellent choice for those who appreciate precision and want to avoid the bulk of stacked pre-cut shims.

Midwest Fastener Shims: A Solid, No-Frills Choice

Midwest Fastener shims are designed for the homeowner who prefers utility over bells and whistles. These are straightforward, flat steel shims that provide a reliable surface for shimming base cabinets or leveling appliances within cabinetry alcoves.

They are particularly effective for leveling heavy pantry cabinets that need to be anchored to the floor. The simplicity of their design ensures they remain stable even when subjected to vibrations from nearby appliances like a dishwasher or laundry machine.

Choosing these is a decision to prioritize functionality. They offer the necessary support to keep cabinets flush and secure without the cost associated with branded, multi-piece kits.

K&S Engineering Steel Sheet: For Custom DIY Shims

For the ultimate custom fit, a thin sheet of high-quality steel can be used to fabricate shims that are perfectly tailored to a unique gap. By using tin snips, the homeowner can create shims that are wider or narrower than anything sold in a standard kit.

This approach is ideal for complex installations where shims must be hidden deep behind the cabinet face. It allows for a more tailored approach to floor-to-cabinet transitions, especially in corners where multiple cabinet frames meet.

Always remember to sand down any sharp, cut edges before sliding the shim into place to prevent damage to the cabinet interior. This DIY method requires a bit more patience but offers the highest degree of customization for difficult kitchen layouts.

How to Pick the Right Shim Thickness for the Job

• Assess the gap first: Use a level to determine how much height is needed at the lowest corner of the cabinet.
• Avoid “doubling up” too much: While stacking is common, try to use a shim close to the required thickness to maintain stability.
• Consider the material weight: Use thicker steel gauges for lower cabinets and lighter gauges for upper wall cabinets.
• Measure before you buy: Most shim sets list their thickness in thousandths of an inch; measure the largest gap in the kitchen to ensure the kit includes the necessary size.

Steel vs. Wood vs. Plastic: Which Shim Is Best?

Steel shims are the gold standard for long-term durability and compression resistance, particularly under heavy granite or quartz countertops. Wood shims, while inexpensive, can shrink or swell with seasonal humidity, leading to “ghost” movements in the cabinetry.

Plastic shims are convenient and easy to break off, but they may compress or crack under the extreme weight of modern kitchen appliances and stone surfaces. For any permanent installation, especially in areas prone to moisture, steel remains the superior choice for reliability.

The decision ultimately comes down to the longevity of the project. If the goal is a kitchen that will not require releveling in five years, steel is the only reliable path.

A Quick Guide to Stacking Shims for a Solid Fit

When multiple shims are required to reach the desired height, always stack them with the largest on the bottom and the smallest on the top. This prevents the stack from sliding or “walking” during the installation process.

For added security, apply a small dab of construction adhesive between each steel shim once the cabinet is perfectly level. This creates a solid, unified block that will not shift even if the floorboards expand or contract.

Finally, always ensure that the shims extend fully under the cabinet frame. A shim that only supports the very edge of the wood can lead to stress points and potential cracking of the cabinet base.

Whether tackling a full kitchen renovation or simply fixing that one annoying cabinet door that refuses to close properly, steel shims offer a robust and permanent fix. By choosing the right thickness and material for the job, you ensure that your cabinetry remains stable, level, and functional for the long haul. Remember that while the upfront cost is higher than wood or plastic, the durability of steel makes it the most economical choice over the life of your home.