Originally Posted On: https://www.palletone.com/getting-to-the-bottom-of-a-pallet-design-problem/

Reengineering a pallet to address new challenges is nothing new for pallet designers. Over 80 years ago, the pallet bottom face, also known as the bottom deck, was first introduced. It marked a historic moment in the evolution of the modern pallet. In this blog, we literally get to the bottom of pallet design. We start with a brief history of bottom face and what it meant for pallet usage. Then we consider some basic bottom deck options used today and where their adoption makes the best sense.

Before the double-faced pallet, patented by George Raymond and William House, the existing approaches to stacking loads were problematic. Operators used dunnage blocks and single-faced pallets, commonly known as skids. Dunnage blocks were used as spacers for stiff loads such as lumber or steel. They were placed manually by lift truck operators. 

The innovation of the skid, the top boards attached to vertical spacers, allowed for a greater variety of materials to be unitized. It also offered the benefit of not requiring the lift truck operator to lean out of his truck to place the spacers, so it was a much safer practice. Still, the skid had limitations. The stringers were prone to collapse, a problem largely rectified by adding bottom boards.

Additionally, the lack of a bottom deck meant that load-bearing pressures were borne by only the stringers. As a result of this concentrated pressure, it limited the types of loads that could be stacked without causing crushing damage to the load below. The addition of the bottom boards helped disperse weight, thereby increasing the range of goods that could be safely stacked. 

As Raymond and House described in their 1937 patent, the bottom deck provided “a relatively large surface to support the weight thereof upon such a stack or pile of small articles, in such a manner as to prevent localization of the weight on the supporting beams and hence possible disruption of the stacked articles.”

These days, two popular types of board configurations are the unidirectional base and the perimeter base. In the unidirectional pallet, all the deck boards are oriented in the same direction. For example, the GMA pallet has five unidirectional bottom boards. When designing a pallet that must be conveyed, having the boards run perpendicular to the rollers will provide smooth conveyance as opposed to bottom boards parallel to the rollers. This orientation can result in a bumpy ride if rollers are too far apart. 

The other popular approach, the perimeter base, is commonly seen in rental block pallets, for example. It features boards aligned in two directions. Compared to the GMA, it offers improved rigidity, conveyability in both directions, and increased bottom deck coverage to reduce product crush damage for stacked loads.

There are other bottom options listed in NWCPA’s Uniform Standard for Wood Pallets. These include the cruciform base and the overlapping base. The cruciform is very much like the perimeter option, with the addition of short connector boards to provide even more bottom deck coverage and ease of conveyability. In the overlapping base, the bottom boards are oriented in opposite directions, and, as the name suggests, they overlap. This approach is seen on the CP7 chemical pallet, for example. 

The next time you walk through the warehouse, take a moment to look up at the pallets in your storage racks. Over 80 years ago, the development of the bottom face helped set the stage for the development of modern palletized handling. It remains an essential consideration for pallet designers charged with optimizing unit load handling in your ever-changing supply chain.