6 Pallet Rack Shims For Uneven Barn Floors To Level Units

Converting an old barn into a functional storage space often reveals the harsh reality of uneven concrete or packed-earth foundations. Pallet racking requires a perfectly level base to support heavy loads of feed, machinery parts, or seasonal tools without risking a structural collapse. Utilizing the right shims turns a shaky, hazardous setup into a professional-grade organization system that lasts for years.

Disclosure: As an Amazon Associate, this site earns from qualifying purchases. Thank you!

Steel King Slotted Steel Shims: Most Versatile

Steel King slotted shims earn their reputation as the “go-to” for barns where floor inconsistencies vary from bay to bay. The slotted design allows for quick adjustments after the baseplate bolt is already in place, saving significant time during a multi-unit installation. These shims provide a high weight-bearing capacity that is essential when storing dense items like bags of fertilizer or heavy metal components.

Because of their durability, these are the ideal choice for farmers who expect to reconfigure their storage space as the seasons change. The steel construction resists crushing even under the immense pressure of fully loaded uprights. If the barn floor has multiple pitch points, stock a variety of these thicknesses to ensure every frame sits flush.

Cogan Horseshoe Shims: Easiest Installation

Cogan horseshoe shims are designed for speed and simplicity. The open-center shape slips easily around existing anchor bolts without the need to completely dismantle or reposition a heavy upright frame. For a solo farmer working alone in the barn, this efficiency is a massive benefit that prevents unnecessary physical strain.

The design creates a secure fit that stays in place once the anchor bolt is tightened down. They are particularly effective for minor floor dips where a quick fix is required to level a unit before it is fully loaded. Use these when time is at a premium and the leveling needs are relatively predictable across the floor space.

Unarco U-Shaped Shims: For Tight Spaces

When working in a barn with limited clearance or pre-installed baseplates that sit flush against the floor, Unarco U-shaped shims provide the necessary profile. Their compact shape ensures that the shim remains hidden beneath the baseplate, maintaining a clean look while providing critical support. They are engineered to distribute weight evenly across the base, preventing localized stress on the concrete floor.

These are best reserved for situations where space is too tight to maneuver bulky or uniquely shaped shims. By focusing on precision leveling in narrow footprints, they allow for tighter row spacing without compromising stability. Invest in these if the barn layout requires maximum space efficiency and low-profile leveling components.

Ridg-U-Rak Shim Plates: Heavy-Duty Choice

Ridg-U-Rak shim plates are the heavy-duty workhorses for barns housing heavy harvesting equipment or large quantities of bulk feed. Unlike smaller shims, these plates often cover the entire footprint of the baseplate, providing superior load distribution. This added surface area is vital for older, softer concrete that might crack under the concentrated pressure of a single anchor point.

Select these plates when building high-capacity racking systems that will remain stationary for long periods. They provide a structural integrity that smaller shims simply cannot match in extreme load environments. If the floor quality is questionable or the loads are exceptionally heavy, these plates offer the most reliable insurance against floor failure.

Interlake Mecalux Shims: Best for Damp Floors

Dampness is the silent enemy of barn storage, often leading to hidden corrosion under baseplates. Interlake Mecalux shims are designed with materials and coatings that withstand the moisture cycles typical of unconditioned agricultural buildings. Their specific composition helps mitigate the risk of rust transferring from the shim to the rack structure, protecting the long-term investment in the shelving unit.

Beyond their resilience to humidity, these shims offer consistent thickness and structural rigidity. They act as a vital buffer between the damp concrete and the metal baseplate, preventing galvanic corrosion. For any barn prone to seasonal dampness or proximity to livestock areas, choosing these moisture-resistant options is a smart, preventative maintenance move.

Speedrack Slotted Shims: Budget-Friendly Pick

For the hobby farmer balancing the costs of feed, seeds, and infrastructure, Speedrack slotted shims offer a practical, cost-effective solution. They provide the necessary leveling capability without the premium price tag of heavy-duty plates. While they may not offer the same material thickness as industrial options, they are more than adequate for light-to-medium duty racking loads.

These shims are the perfect choice for small-scale projects where the floor is relatively flat but requires slight adjustments to prevent unit sway. They are easily stackable for minor leveling needs and perform well under standard storage conditions. Use them to keep the project on budget without sacrificing the structural safety of the racks.

How to Properly Install Pallet Rack Shims

Begin by placing a high-quality spirit level along both the depth and length of the rack upright to identify exactly where the gaps exist. Once the low spots are identified, lift the frame using a hydraulic jack or a heavy-duty pry bar, taking extreme care to stabilize the load safely. Slide the appropriate thickness shim under the baseplate and align it carefully with the anchor bolt.

Never stack more than three shims at a single point, as this can create an unstable “fudge factor” that compromises the entire structure. If the gap requires more than three shims, it is a sign that the floor is too uneven and requires a more permanent leveling compound or grout. Once the shim is in place and the rack is level, tighten the anchor bolt to the manufacturer’s specified torque to ensure a solid bond with the floor.

Why Level Racking Is a Critical Barn Safety Step

An unlevel pallet rack is an accident waiting to happen, particularly as loads shift during the settling of a building. When a rack leans, it places an uneven load on the uprights, which can lead to structural bowing or even a total collapse. This poses a severe risk to stored inventory, equipment, and anyone working near the racks.

Leveling ensures that weight is transferred vertically through the uprights directly into the foundation. It prevents the racking from becoming “top-heavy” or prone to swaying when items are retrieved from the upper levels. Treating the floor as part of the rack’s support system is not just an organizational preference; it is a fundamental safety requirement.

Choosing Shim Material: Steel vs. Plastic

Steel shims are the gold standard for agricultural environments due to their resistance to crushing and extreme weight-bearing capabilities. They do not deform under pressure, ensuring that the rack remains at the exact height set during installation. However, they are susceptible to rust if the barn environment is particularly damp or exposed to acidic materials like salt or fertilizer.

Plastic or composite shims offer an advantage in extremely wet or chemical-rich environments because they are impervious to corrosion. While they are often cheaper and easier to trim, they can creep or deform under sustained, heavy pressure over several years. Reserve plastic shims for light-duty shelves and prioritize steel for the main racking units that hold the majority of the weight.

Measuring Floor Gaps Before You Buy Shims

Avoid the frustration of buying the wrong parts by using a simple wedge-shaped gap gauge or a set of automotive feeler gauges. Measure the distance between the bottom of the baseplate and the floor at every anchor point of the upright frame. It is common for each leg of a single unit to require a different shim thickness, so record these measurements individually for every single hole.

Do not guess based on visual inspection, as even an eighth-inch difference can lead to a significant tilt when the rack is ten feet tall. Take measurements at the exact spot where the anchor bolt sits, as the floor may be uneven even within the small footprint of the baseplate itself. Accurate data collection at this stage is the difference between a quick, successful install and an afternoon of repeated adjustments.

A level rack is the bedrock of an organized and efficient barn, turning a chaotic pile of supplies into a streamlined system. By taking the time to measure correctly and selecting the right shims for your specific floor conditions, you ensure that your investment is secure for seasons to come. Prioritize safety, choose durable materials, and enjoy the peace of mind that comes with a perfectly stable storage solution.