In short: honeycomb cardboard delivers vertical compression strength of roughly 15 to 90 tonnes per square metre depending on thickness, liner grade and cell size. For a 30 mm standard panel, expect about 25 t/m² instantaneous and 8–10 t/m² under sustained load over 30 days. Dimensioning follows three steps: calculate distributed load, apply a creep coefficient, then verify the actual bearing area. Skipping the third step causes most failures.
Where the strength comes from
Honeycomb paperboard is a sandwich material: a hexagonal kraft paper core bonded between two board liners. Its performance comes from geometry, not from the material itself.
The hexagonal cell walls run perpendicular to the liners. Under vertical load they work in pure compression along their strongest axis, exactly like the columns of a building. That is how a material of 30–80 kg/m³ can carry loads that solid timber barely exceeds, at five to ten times less weight.
Three parameters drive the final figure.
- Cell size — the distance between opposite walls of the hexagon. A 10 mm cell gives a far denser and stronger structure than a 30 mm cell at equal area.
- Core paper grammage, typically 100–200 gsm, which sets the buckling load of each wall.
- Liner quality, which spreads point loads across many cells. A weak liner punctures locally long before the core reaches its limit.
Typical strength values
| Thickness | Cell size | Instantaneous compression | Sustained 30 days | Areal weight |
|---|---|---|---|---|
| 10 mm | 10 mm | 30–40 t/m² | 10–13 t/m² | 1.4 kg/m² |
| 20 mm | 15 mm | 25–32 t/m² | 8–11 t/m² | 1.8 kg/m² |
| 30 mm | 20 mm | 20–28 t/m² | 7–9 t/m² | 2.2 kg/m² |
| 50 mm | 25 mm | 15–22 t/m² | 5–7 t/m² | 3.0 kg/m² |
| 80 mm | 30 mm | 12–18 t/m² | 4–6 t/m² | 4.1 kg/m² |
These figures assume 23 °C and 50% relative humidity, the ISO 187 conditioning standard. They must be corrected for your real conditions before use.
The three-step calculation
Step 1: distributed load
Divide the mass carried by the effective bearing area. Effective bearing area is not panel area — it is the area actually in contact. A 1,200 × 800 mm panel carrying a 400 × 300 mm case works over 0.12 m², not 0.96 m².
Example: 600 kg over 0.96 m² gives 0.625 t/m². The same 600 kg concentrated on 0.12 m² gives 5 t/m². That factor of eight explains most field failures.
Step 2: creep coefficient
Honeycomb creeps — it settles slowly under constant load. Industry practice is to retain one third of instantaneous strength for loads held beyond 30 days, and one quarter beyond six months.
Step 3: humidity correction
At 85% RH, strength falls by roughly 45%. At 65% RH the loss is around 20%. This is the most frequently underestimated factor on sea-freight export, where container humidity can exceed 90% for days at a time.
The full expression: allowable load = instantaneous strength × duration factor × humidity factor × safety factor (0.7 recommended).
Typical applications and associated loads
Pallet layer pads
A 10–20 mm honeycomb pad handles layer separation up to about 1.5 t/m². This is the most widespread use, notably on bottles, drums and metal parts.
Load-bearing trays and platforms
From 30 mm upward, honeycomb replaces plywood for loads up to around 800 kg per tray. The double benefit is weight saving on air freight and exemption from ISPM 15 phytosanitary treatment.
Blocking and bracing
Triangular honeycomb wedges immobilise loads in trailers and containers. Here the governing constraint is lateral puncture resistance, not vertical compression.
Partitions and structures
Large-format honeycomb panels also serve as temporary partitions, exhibition stands and short-life furniture. The dominant stress there is bending, not compression, so the calculation runs on the sandwich’s second moment of area.
How to measure — and what to ask for
Flat crush test (FCT)
A 100 × 100 mm specimen is crushed between two platens at constant rate; peak stress is recorded. This is the datasheet number. It measures core performance, not finished panel performance.
Box compression test (BCT)
Run on the complete pack, divider and product included. It is the only test genuinely representative of warehouse stacking. A 30–50% gap between theoretical FCT and measured BCT is common, always in the unfavourable direction.
Accelerated creep test
The specimen is held under constant load at controlled temperature and humidity for 7 to 28 days. The resulting curves allow extrapolation to six months. Ask for this whenever your goods sit in a warehouse for long periods.
The five costliest dimensioning errors
- Confusing instantaneous and sustained load. A panel that passes at 25 t/m² collapses at 12 t/m² after three weeks in storage.
- Ignoring point loads. A machine foot, a castor or a sharp edge punches through a standard liner without difficulty.
- Overhang. A panel projecting beyond its support works in bending, where honeycomb is much weaker.
- Underestimating handling cycles. Each lift creates a stress peak that can reach twice the static load.
- Ignoring humidity pickup in buffer storage. A panel stored three weeks in an unheated hall has already lost significant capacity before being loaded.
Environmental balance and alternatives
At equivalent protective performance, a 30 mm honeycomb panel weighs roughly 2.2 kg/m² against 12–15 kg/m² for 10 mm plywood. On air freight that differential converts directly into money saved.
The material is mono-component: kraft paper and starch adhesive. It rejoins the paper stream with no dismantling or separation, at European recycling rates above 80%. FSC-certified fibre lets you document the whole system within an ESG framework.
Against technical foams, honeycomb loses on very high-energy shock absorption but wins on static load capacity, cost and end of life. The pragmatic answer is often to combine them: honeycomb for structure, small foam pads only at critical contact points.
Designing the bearing surface, not just the panel
Most honeycomb failures in the field are not material failures. They are bearing failures — the panel was strong enough, but the load was introduced badly.
Spread the load
Wherever a concentrated load meets the panel, insert a load-spreading layer: a rigid liner board, a plywood offcut or a second honeycomb sheet with cross-oriented cells. This turns a punching problem into a compression problem, which honeycomb handles well.
Support the edges
Panel edges are the weakest zone because half the cells are open. Where an edge takes load, close it with a folded liner, an edge strip or a returned flap. This single detail routinely adds 20–30% to usable capacity.
Keep the load path straight
Honeycomb is highly anisotropic: superb along the cell axis, mediocre across it. Any design that turns vertical load into shear or bending across the cells throws away most of the material’s performance.
Specifying honeycomb in a purchase order
A vague specification is the root cause of most disappointments. Six parameters should appear on every order.
- Panel thickness and permitted tolerance.
- Cell size — the single biggest driver of strength, and the one most often left unstated.
- Core grammage and liner grade on each face, which need not be identical.
- Adhesive type, standard or water-resistant.
- Fibre certification, FSC or PEFC, with a verifiable chain-of-custody number.
- Conditioning and packing, including flat storage and moisture protection during transport.
Two panels described simply as “30 mm honeycomb” can differ in compression strength by a factor of two. Specifying these six lines removes that ambiguity and makes quotations genuinely comparable.
Frequently asked questions
Is honeycomb stronger than double-wall corrugated?
In vertical compression, yes — by a factor of three to six at comparable thickness. In burst and tear resistance, corrugated keeps the advantage. The two materials are complementary rather than competing.
Can pallets be stacked on honeycomb pads?
Yes, provided sustained load is calculated and flat bearing is guaranteed across the whole surface. Honeycomb pads are used routinely in double and triple stacking in the beverage industry.
What is the service life of a honeycomb panel?
Indoors, dry and unloaded, several years. Under sustained load, creep means you should think in mission duration rather than service life: time under stress is what counts.
Are moisture-resistant grades available?
Yes. Water-resistant adhesives and treated liners limit performance loss in humid conditions at a 10–25% premium. They do not replace shroud protection on long sea-freight routes.
Key takeaways
Honeycomb paperboard is a genuine structural material, but it is not dimensioned like ordinary board. Real allowable load is often a quarter of the catalogue figure once creep, humidity and a safety factor are applied.
Nidatec, the Estic-Maillot group’s honeycomb specialist, produces panels from 10 to 100 mm and supports load calculation on customer applications. Request a load study for your project.