Single wall suits most parcel despatch; double wall earns its place when cartons are stacked, palletised, heavy or travelling far. Specifying double wall throughout is the common and expensive default - it adds cost, weight and storage volume to every parcel that never needed it.
What the difference actually is
Single wall board is one fluted layer between two liners. Double wall is two fluted layers and three liners, usually combining two different flute profiles so that one contributes cushioning and the other crush resistance. Triple wall adds a third and is a heavy-duty material rather than a general one.
The practical consequences go beyond strength. Double wall is thicker, so it takes more storage space flat and more volume assembled. It is heavier, which matters on weight-banded carriage. And it folds less crisply, which affects both pack speed and print quality.
| Single wall | Double wall | Triple wall | |
|---|---|---|---|
| Typical use | Parcel despatch | Palletised or heavy | Industrial, very heavy |
| Stacking | Limited | Good | Excellent |
| Cost per carton | Lowest | Higher | Highest |
| Flat storage volume | Lowest | Higher | Highest |
| Weight | Lightest | Heavier | Heaviest |
| Print quality | Good | Adequate | Poor |
| Assembly speed | Fastest | Slower | Slowest |
Single, double and triple wall compared.
The questions that decide it
- Will it be stacked? A carton carrying others needs edge crush performance. One travelling alone in a parcel network mostly needs burst strength at the corners.
- How heavy is the contents, and how is the weight distributed? A dense item on a small footprint concentrates load regardless of total weight.
- How long is the journey, and how many handovers? Compression is cumulative; a long palletised route is harder on board than a short parcel one.
- What are the storage conditions? Board loses strength with moisture, so a chilled or damp environment effectively downgrades whatever you specified.
- Does it need to print well? Fine print and small reversed-out text suffer on double wall because the flute shows through.
Specifying up is not caution, it is cost - and specifying down to save money on a palletised load is how a stack arrives crushed. Both mistakes are made by treating the grade as a general preference rather than a decision per line.
Where businesses get it wrong in both directions
Over-specification is the commoner error and the quieter one. A business that standardised on double wall years ago for one heavy product is frequently still using it for everything, paying for strength, weight and storage volume on every parcel that would have been fine in single wall.
Under-specification is rarer but louder, because it produces damage. It usually happens when a carton is chosen for a single unit and then gets used palletised, or when a product gets heavier without the packaging being revisited. The failure is almost always compression in the bottom layer rather than anything happening in transit.
Both are easier to see on one page than in isolation: the grades in use across a range are listed under packaging supplies, and where the answer turns out to be a different size rather than a different grade, that is Cardboard Boxes: How to Specify the Right One rather than this decision at all.
Getting more out of the board you already have
- Fit first. A correctly sized single wall carton frequently outperforms an oversized double wall one, because a product that cannot move is not loading the walls.
- Protect the corners. Edge and corner protection carries compression far more efficiently than upgrading the whole carton - see Corner Boards, Edge Protection and Pallet Stability.
- Column stack rather than interlock where the product allows it; stacking pattern changes load-bearing more than a grade change does.
- Keep the load inside the pallet footprint. Overhang loses the support of the pallet and the bottom layer pays for it.
- Specify per line, not per business. Two grades across a range is normal and usually cheaper than one.
How to tell which grade you are actually using
A surprising number of businesses do not know what grade they are buying, because it was specified years ago by somebody who has left and has been reordered by part number ever since. Two checks settle it without involving anyone.
- Look at a cut edge. Single wall shows one row of flutes between two liners. Double wall shows two rows separated by a middle liner. It is visible on any offcut.
- Check the board grade on the carton itself. Most trade cartons carry a printed board specification on an inside flap, which gives the liner weights and the flute profile.
Then compare that against what the cartons are actually doing. If single wall cartons are being palletised three high and arriving crushed at the bottom, the grade is wrong for the use. If double wall cartons are going out as single parcels and arriving intact every time, you are paying for performance the journey never asks for.
Either way the answer is a specification per line rather than a house standard. Two grades across a range is normal, and it is almost always cheaper than one - see packaging review and cost reduction if you want that looked at across the whole list.
The short version
- Single wall covers most parcel despatch; double wall is for stacked, heavy or long-haul work.
- Double wall costs more in money, weight, storage volume and pack speed.
- Moisture downgrades whatever grade you specified.
- Corner protection carries compression more efficiently than upgrading the board.
- Specify per line rather than standardising the whole range on one grade.
Frequently asked questions
Is double wall always stronger than single wall?
It is stronger in the sense that matters for stacking and heavy loads, yes. But a correctly sized single wall carton frequently protects a product better than an oversized double wall one, because fit does more work than grade.
Do I need double wall for parcel despatch?
Usually not. Parcels are handled many times but rarely stacked under sustained load, so burst strength at the corners matters more than compression performance. Heavy single items are the exception.
Does board lose strength when damp?
Yes, significantly. A grade that performs in a dry warehouse can lose a lot of its performance in a cold store or after standing outdoors, which is why storage conditions belong in the specification.
Can I mix grades across my range?
Yes, and most businesses should. Standardising everything on one grade means either over-paying on the light lines or under-protecting the heavy ones.
What about triple wall?
It is a heavy-duty industrial material for very heavy or very large items, and it frequently replaces a timber case. It is not a general upgrade - see industrial packaging.