Single vs. Double-Deep Selective Rack: Which is the best option for you?

Selective pallet rack is one of the most popular inventory storage options in use today. In a typical warehouse application, the racks install back-to-back, in a way that creates aisleways for forklifts to access the palletized inventory.

This rack system is available in a “double-deep” arrangement option, potentially increasing inventory storage by another 20-40%. However, the double-deep option has specific equipment requirements to work at maximum efficiency. Today we will compare the single and double-deep options to determine the best selective racking option for you.

The Selective Racking System

Selective rack systems work well if you handle large quantities of palletized products and a limited number of SKUs. Single and double-deep options both utilize the same pallet racking system components. So either option provides the following benefits:

  • The installation process and maintenance are simplified thanks to selective rack’s ease of assembly.
  • Cubing your inventory is easier because the bays match the needed pallet size.
  • LIFO inventory rotation.
  • Depending on your warehouse configuration or layout, there is a wide variety of ratings, widths, and heights available.
  • Vertical frames anchor to the existing concrete slab and can reach a maximum height of 30′. The racking system can be attached to the building structure (roof and walls) for additional strength and stability.
Selective pallet rack in the very common single deep configuration

The Double-Deep Option

Single deep assemblies install back-to-back, creating the aisleways (typically 8-9′ wide) needed for your equipment and employees to work efficiently. Each pallet of inventory is directly accessible from the aisle, with standard material handling equipment.

With the double-deep racking option, a maximum of four pallet rack assemblies can install back-to-back-to-back-to-back. This arrangement creates double-deep storage on each side of the aisleway.

The double-deep layout can eliminate up to fifty percent of the needed aisles than a standard selective pallet rack system layout. Fewer aisleways translate into more available storage space for your product inventory.

The double-deep selective rack option is exceptionally well suited for:

  • Cold storage where the double-deep option maximizes storage while minimizing utility costs.
  • Dry storage where durable goods don’t have expiry concerns.
  • Medium to long-term shelf life due to LIFO (Last In First Out) loading requirements.

The double-deep racking option maximizes the potential inventory storage of your building. The improved flow and accessibility benefit your workers’ productivity and efficiency as well.

Double-deep configured selective pallet rack.

Equipment Requirements for Double-Deep Rack

Before you decide the double-deep option is the solution for your warehouse, there are a few specific equipment requirements to consider.

The standard forklift tangs won’t reach pallets on the rear rack because they are too short. With the double-deep configuration, your existing forklifts will require modification or possibly even replacement.

Luckily, three different material-handling equipment options work exceptionally well with the double-deep racking system:

Telescopic Forks

This option allows any non-pantograph forklift to handle a double-deep selective pallet rack layout. Replacing your standard tines with a set of telescopic tines enables the lift to reach the rear-most pallets.

The retro-kit is an affordable option compared to replacing an entire fleet of forklifts. Kits include the telescopic forks and any additional hardware (lines, pumps, and fittings) required for a complete installation.

The driver has clear visibility when handling inventory as only the telescopic forks and the pallet are moving in and out.

Telescopic forks (with the proper rating) can also allow the lift to carry two pallets simultaneously, increasing productivity and worker efficiency.

Always check with the lift manufacturer before making any modifications to your equipment.

Pantograph Conversion Kits

With this retro-kit option, a pantograph (push/pull) assembly mounts to the mast, allowing double-deep inventory access. These kits include the scissor assembly and required components for a complete conversion.

Driver visibility may be affected at times due to the scissor-action of the pantograph.

Always check with the lift manufacturer before making any modifications to your equipment.

Pantograph or Scissor Mast Lifts

Pantographic reach trucks are dedicated lifts designed explicitly for double-deep pallet stacking duties. Their counter-balanced trucks allow for narrower aisleways which can increase inventory storage.

Their compact and efficient design results in smoother operation, decreasing pallet and product damage, and faster load/unload times.

Forklift requirements should be considered when thinking about a double-deep rack layout.

Additional Selective Rack Features/Options

Some racking manufacturers provide additional options such as:

Replaceable rollers or guides that assist lift drivers as they move inventory in and out of the racks.

Replaceable feet/anchor point kits allow for rack repair without entirely unloading inventory.

“Cant” legs where the front leg tapers in toward the rear support member. The broader access point minimizes potential forklift damage to the racking components.

The Best Option for Your Warehouse

At first glance, this racking option appears to be a no-brainer decision. Why wouldn’t you choose the double-deep option to increase your potential storage capacity?

  • It’s not the best option for your building. Depending on your building’s size and layout, the double-deep option may only provide minimal storage gains. Areas with an irregular shape or angled walls don’t always work well with the double-deep racking system.
  • Equipment costs are not budget friendly. The double-deep option requires specific equipment for maximum efficiency. The price for new lifts or upgrading current equipment could be cost-prohibitive.

There are a variety of other factors to consider before committing to a double-deep racking system.

  • Product flow
  • Shelf life
  • Inventory rotation
  • Pallet sizes
  • Building specifics

Discussing your specific needs and factors with a material handling expert will help you decide if the single or double-deep racking option is the best option for you.

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