Pallet-Racking System Types

Selective rack gives a lift operator direct aisle access to each pallet position. It is the most common choice for warehouses with many SKUs, changing inventory or frequent access requirements. Its primary tradeoff is the floor area devoted to operating aisles.

Double-deep rack stores one pallet behind another. It increases storage density by reducing aisle count, but the rear pallet is blocked until the front pallet is removed. It normally requires compatible reach equipment and works best when each lane holds the same SKU or compatible inventory.

Drive-in rack creates deep lanes supported by pallet rails. A forklift enters the structure to store or retrieve pallets. It provides high density for large quantities of similar products, typically using last-in, first-out inventory flow. Consistent pallets, loads and operator discipline are especially important.

Drive-through rack is accessible from both ends of the storage lane. It can support different loading and retrieval patterns than single-entry drive-in rack. The system needs aisles at both ends and careful control of lane inventory, lift-truck movement and rack protection.

Push-back rack stores pallets several positions deep on carts or inclined lanes. Loading a new pallet pushes earlier pallets farther into the lane; unloading allows the next pallet to advance. The forklift stays in the aisle, and each lane usually operates last-in, first-out.

Cantilever rack uses arms extending from vertical columns and has an open loading face. It is commonly used for lumber, pipe, tubing, furniture, steel and other long or irregular products. Product length, weight, deflection, arm capacity and column spacing determine the correct configuration.

Stack racks are portable storage frames that can be stacked vertically when loaded. Depending on their design, they may nest or disassemble when empty. They are useful for seasonal products, tires, furniture, irregular items and temporary storage where permanent rack offers limited flexibility.

Pallet-flow rack is the most common high-density rack designed around first-in, first-out flow. Pallets are loaded from one side and move toward the retrieval side. Selective rack can also support FIFO through inventory procedures because each pallet remains directly accessible.

Push-back and single-entry drive-in rack generally operate last-in, first-out within each lane. The last pallet loaded becomes the first available pallet. This arrangement works best when product shelf life and inventory rules allow that sequence.

The answer depends on the building and inventory. Drive-in, pallet-flow and some push-back systems can produce high position counts, while very narrow aisle selective rack can provide high density with greater selectivity. Usable density should account for lane utilization, rehandling, throughput and SKU distribution.

Many systems allow beam levels to be adjusted, but every change has limits. Moving beams can alter upright-frame capacity, pallet clearance and sprinkler compatibility. Adding, removing or relocating rack can also affect approved permit drawings. Evaluate changes before implementation and retain the original engineering documents.