Follow the weight from top to bottom
Think of a stack as a path carrying force downward. If a carton’s supported edges align with the carton below, the load path differs from one pressing into the middle of a weaker panel.
FedEx’s pallet-packing guidance distinguishes column stacking, which can improve top-to-bottom compression performance, from interlocking arrangements used for stability with suitable rigid contents. Its guidance also warns about unsupported overhang. This is not a rule that one stacking pattern is best for every product.
A simple static example
Suppose four equal cartons support a flat upper layer weighing 100 kg. In an idealised arrangement distributing the load equally, each carton carries the equivalent of 25 kg from that layer. If poor support concentrates the same load on two cartons, each receives 50 kg.
This arithmetic demonstrates distribution only. It is not a safe stacking limit: it ignores carton strength, uneven support, movement, time and other loads. The example explains why dividing total weight by every carton on the pallet can be misleading.
Stability and compression are different requirements
A stack can resist tipping yet overload the cartons beneath it. Another can have strong vertical support but need a better method of containing the units together. Solve both problems instead of calling a visually neat pallet “secure.”
When discussing a repeated shipment with a packaging specialist, provide photographs of the whole load and its base, not just the damaged panel. Include where the pallet was handled and the package specification. Those observations make the investigation more useful than simply ordering thicker boxes after every incident.
Turn the lesson into a packing instruction
Write an approved configuration showing carton orientation, layer arrangement, base support and the method used to keep the load together. Define the action when the order is short a carton; staff should not invent a new support pattern without review.
For collection by WTM, report the finished pallet dimensions and stackability requirement. Declaring a load non-stackable tells dispatch about usable space; it does not repair an unstable pallet. Transport equipment and the package each have a role.
Does heavier wrapping make weak cartons stronger?
Do not assume it solves a compression problem. Containment and load-bearing capability are different design questions, and excessive force can create another problem.
Should I copy a pallet pattern from another product?
Not without checking the contents, cartons and handling conditions. An arrangement suitable for rigid containers may not suit cartons containing compressible goods.
