Single wall board has one fluted layer between two flat liners. Double wall board has two fluted layers and three liners. That describes the construction, rather than a universal weight limit.
What are the layers in a cardboard box?
The wavy paper inside corrugated board is called fluting. The flat sheets are liners. Together they form the board that is cut and folded into a box. FEFCO, the European corrugated packaging association, explains this construction.
| Construction | Fluted layers | Flat liners | Before choosing |
|---|---|---|---|
| Single wall | 1 | 2 | Check the actual board grade and box specification |
| Double wall | 2 | 3 | Check the actual board grade and box specification |
Does double wall always mean stronger?
Do not compare boxes using wall count alone. Ask how the actual boxes perform for your intended use. Board grade, flute combination, size, condition and closure can all affect the packing decision. The weight and arrangement of the contents matter too.
A label such as “heavy duty” is not a complete specification. Ask what supports it, rather than transferring a weight claim from one supplier’s box to another.
How much weight can a box hold?
There is no single safe weight for all single wall or all double wall boxes. Request the manufacturer’s limit and the conditions under which it applies. A stacking test, for example, answers a different question from how a loaded box is carried.
Explain your product, packed weight, handling method and storage conditions when requesting advice. Use a representative packed sample to check the proposed arrangement before rolling it out.
What should I ask the supplier?
- What are the usable internal dimensions and any size tolerance?
- What board grade and flute construction does this exact product use?
- What assembly and sealing method is required?
- Which performance claims have been tested, and under what conditions?
- Will the same specification be supplied on repeat orders?
Choose the size and the protection together
Extra wall layers do not replace protection around the contents. First plan the full packing arrangement, then compare its dimensions with the usable space. Our measuring guide explains that step.
For business orders, keep the resulting specification with your product record. For a move, also consider whether each loaded box can be handled comfortably.