Referring to the Table: Pallet Yield above, the number of pallets in a container can be doubled by double stacking of pallets, but at the expense of the total height and the gross weight of each loaded pallet. Stack loading is possible only if the cargo underneath can stand up to the compression from the overlaying pallet, and the center of gravity does not exceed half the height of the container.
To prevent the cargo beneath the stack from being torn and damaged, use dunnage like plywood, compressed particle board, fiberboard, and matting, to separate the lower and upper pallets. L-shaped wood or steel corner supports can be used to give added strength to the packages.
To prevent the pallets from shifting and crushing inside the container, block and brace the pallets at the voids with lumber and plywood, or secure them with chains, ropes and straps to the bull rings at the upper and lower corners of the side walls of the container.