Corner boards transfer the compression load down through the corners of a pallet rather than through the cartons. Combined with keeping the load inside the pallet footprint and stacking in columns, they do more for stability than upgrading board grade or adding film.
Why pallets fail, in order of frequency
Pallet failures are predictable and most of them have nothing to do with the material the cartons are made from. In rough order of how often we see them, the causes are overhang, the wrong stacking pattern, no base locking in the wrap, and only then board grade.
| Cause | What it looks like | Fix |
|---|---|---|
| Overhang | Bottom layer crushed at the edges | Keep the load inside the pallet |
| Interlocked stacking | General crushing through the stack | Column stack where possible |
| No base locking | Load leaning or shifted off the pallet | Wrap the base to the deck |
| No corner protection | Film cutting in, corners crushed | Corner boards up each edge |
| Board grade too light | Uniform crushing under load | Specify by stacking, not weight |
| Uneven layers | Localised collapse | Layer pads between tiers |
The usual causes of a pallet arriving damaged.
How corner boards work
A carton carries compression mainly in its vertical edges, not in its faces. Corner boards - L-shaped lengths of laminated board - run up the corners of a palletised load and provide a continuous vertical member, so the weight of upper layers transfers down the corner posts rather than through each carton in turn.
They also stop stretch film cutting into the load. Film applies its containment force unevenly, concentrating at corners, which is exactly where a carton is least able to resist a localised force. The board spreads it.
Column stacking versus interlocking
Interlocking - rotating alternate layers so the cartons bind together - feels more stable and is substantially weaker in compression, because the vertical edges no longer line up. Column stacking, with corners directly above corners, can carry considerably more load.
- Column stack where the load is heavy or the stack is tall, and accept that it needs film or strapping for lateral stability.
- Interlock only where lateral stability matters more than compression - light goods, short journeys.
- Never mix patterns within a stack; the transition layer carries the worst of both.
- Use layer pads between tiers to spread load and stop cartons nesting into each other.
- Keep the top flat, because an uneven top layer loads whatever is stacked on it unevenly.
The components, and what each contributes
| Component | What it does | When it earns its place |
|---|---|---|
| Corner boards | Carry compression down the corners | Any stacked or tall load |
| Edge protectors | Protect edges from film and handling | Sharp or crushable edges |
| Layer pads | Spread load, separate tiers | Mixed or uneven layers |
| Top caps | Protect the top layer and shed water | Stacked or outdoor-stored |
| Pallet bases | Spread load onto the pallet deck | Heavy or concentrated loads |
| Strapping | Tension through the load | Heavy loads - see Strapping Explained: Polypropylene, PET and Steel |
Load protection components.
Diagnosing a recurring pallet problem
- Photograph a failed load as it arrived, before anyone unpacks it. Which layer failed and on which face tells you the cause.
- Check for overhang on a built pallet before it leaves. This alone accounts for a large share of failures.
- Look at the stacking pattern against the weight. Interlocked heavy loads are a common and avoidable error.
- Check the base wraps reach the pallet deck - see Pallet Wrap and Stretch Film: A Buyer's Guide.
- Only then look at board grade. Upgrading board to fix a stacking problem is expensive and does not work.
Where this sits in the wider specification
Load protection is cheap relative to what it protects, and it is frequently the first thing cut when somebody is asked to reduce packaging cost. That is nearly always a false economy: corner boards cost a fraction of a carton and prevent the failure that writes off a whole pallet.
It also interacts with everything else. A load properly corner-protected and column-stacked can frequently drop a board grade, which is a real saving the other way round. See industrial packaging.
A build standard worth writing down
Pallet stability is mostly a process question, and processes that are not written down vary with whoever is on shift. A short written standard - half a page - removes most recurring failures without any material change.
- Load inside the pallet footprint, with a stated tolerance and no overhang permitted.
- Stacking pattern specified per product, columnar by default on anything heavy.
- Layer pads between tiers where layers are uneven or mixed.
- Corner boards on any load above a stated height, rather than at the builder's discretion.
- Base wraps to the pallet deck, with a minimum number stated - see Pallet Wrap and Stretch Film: A Buyer's Guide.
- Top covered on anything stored outdoors or stacked.
- A photograph of a correctly built pallet on the wall, which is worth more than any written description.
That last point does most of the work. Pallet building is learned by copying, so the fastest way to change it is to show what good looks like rather than to describe it.
The short version
- Overhang and stacking pattern cause more pallet failures than board grade does.
- Corner boards carry compression down the corners rather than through cartons.
- Column stacking carries far more load than interlocking.
- Film cannot rescue an overhanging load.
- Proper corner protection can let you specify a lighter board grade.
Frequently asked questions
What are corner boards for?
They run up the vertical corners of a palletised load and carry compression down the corner posts rather than through each carton. They also stop stretch film cutting into the load at the corners.
Should pallets be column stacked or interlocked?
Column stacked for heavy or tall loads, because the vertical edges line up and carry far more compression. Interlocking is weaker in compression and is only preferable where lateral stability matters more.
Why do our pallets keep arriving crushed at the bottom?
Most often overhang - load outside the pallet edge has no support beneath it - or an interlocked stacking pattern on a heavy load. Check both before changing board grade.
Is edge protection worth the cost?
It is one of the cheapest items relative to what it protects. Corner boards cost a fraction of a carton and prevent the failure mode that writes off entire pallets.
Can corner protection let us use lighter board?
Often, yes. If the corners are carrying the compression, the cartons are not, and the grade can sometimes come down - which is worth checking rather than assuming.