# Pallet stacking patterns: column vs interlock

Column stacking puts each carton directly on the one below, so the corners carry the load and the stack is strongest in compression. Interlocked (brick) stacking turns alternate layers so cartons bridge the seams; it is more stable but weaker, because the corners no longer line up. Wrap and corner boards add stability to column stacks.

## Key takeaways

- Corrugated cartons carry most of their load through the corners and side walls.
- Column stacking keeps corners aligned: best compression strength.
- Interlocking ties layers together: better stability, less strength.
- Never overhang the pallet edge, and respect height limits for trucks, containers and racking.

## How a carton carries load

A corrugated carton is strongest at its corners and vertical walls; the middle of the top panel is weak. When the corners of each carton sit directly on the corners below, the load runs straight down through the walls. When they do not, the walls bend and the carton loses a large part of its stacking strength.


## Column stacking

Every layer is identical, so each carton sits squarely on the one beneath. This gives the highest compression strength and is the usual choice for heavy goods and tall stacks. The weakness is stability: columns can lean or separate, so use stretch wrap, strapping, corner boards or a top cap.


## Interlocked (brick) stacking

Alternate layers are turned or shifted so cartons bridge the joints below, like bricks in a wall. The stack locks together and resists sliding, which helps for light cartons and short trips. The cost is strength: corners land on the weak middle of the cartons below, so heavy or tall interlocked stacks crush more easily.


## Which should you use?

| Aspect | Column | Interlock |
|---|---|---|
| Compression strength | Highest | Lower |
| Stability without wrap | Lower | Higher |
| Best for | Heavy goods, tall stacks, long transit | Light goods, short stacks, manual handling |
| Needs | Good stretch wrap, corner boards | Cartons that tolerate bridging |



## Overhang and underhang

Cartons that hang over the pallet edge lose support at their strongest point and are easily crushed by forklift tines or neighbouring pallets. Cartons that leave a large gap at the edge (underhang) can shift. Aim for the layer to cover the deck closely without overhanging.


## Height limits

Plan the stack height from the tightest limit in the chain: racking beams at the warehouse, truck height, the container door (inside height about 2,393 mm in a 20GP or 40GP and 2,698 mm in a 40HQ, typical) or an airline's unit load device. Many sea shipments are stacked to around 1.6–1.8 m including the pallet.

[Plan your pallet layers](https://cartonmath.com/pallet-calculator/?l=40&w=30&h=20&wt=12&pallet=eur&maxh=160): The calculator finds the best layer pattern and shows how high the stack goes.

## FAQ

**Is column stacking stronger than interlocking?**
Yes. Aligned corners carry the load straight down; interlocking puts corners on the weaker middle of the cartons below.

**When should I interlock pallet layers?**
For light cartons and shorter stacks where stability matters more than compression strength.

**How do I stabilise a column stack?**
Stretch wrap, strapping, corner boards, tie sheets between layers or a top cap.

**Can cartons overhang a pallet?**
Avoid it: overhanging cartons lose strength and are easily damaged.

Source page: https://cartonmath.com/guides/pallet-stacking-patterns/
Updated: 2026-10-06
Publisher: CartonMath (https://cartonmath.com)