Sandwich panels are strong enough for structural applications when the panel configuration matches the load requirements of the application. The combination of high-strength fibre-reinforced skins bonded to a lightweight core produces a structure that resists bending, compression, and impact at a fraction of the weight of solid steel or wood. The questions below unpack what that means in practice for truck body builders, trailer manufacturers, and scaffolding companies.
What makes a panel strong enough for structural use?
A sandwich panel achieves structural strength through composite action: two stiff, strong face skins separated by a lightweight core. The skins carry tensile and compressive loads, while the core transfers shear forces between them and keeps the skins at a fixed distance. This separation is what gives the panel its bending stiffness, the further apart the skins, the greater the resistance to deflection under load.
The skin material determines tensile and compressive performance. In glass-fibre-reinforced thermoplastic skins, the fibre content and layup orientation define how load is distributed. A cross-ply skin, with fibres running at 0° and 90°, distributes load in both directions equally. A multi-ply unidirectional layup concentrates strength along a primary axis, useful when the dominant load direction is known. Skin areal weight, fibre volume fraction, and the number of plies all influence how much force the panel can absorb before failure.
The core material contributes compressive strength and shear stiffness. A denser core resists point loads better and prevents the skins from buckling inward under concentrated pressure. The bond between skin and core is equally important: delamination under load is the most common failure mode in sandwich structures, so the quality of that interface is a structural variable, not just a manufacturing detail.
How do sandwich panels compare to steel and aluminum in strength?
Sandwich panels do not match solid steel or aluminium in absolute strength, but they outperform both on a strength-to-weight basis for bending-dominated applications. A well-specified composite sandwich panel can deliver comparable bending stiffness to a steel plate at roughly one-fifth of the weight. For commercial vehicle and scaffolding structural applications, trailer floors, truck body walls, scaffold decks, this trade-off is highly favourable.
Steel is stronger in tension and compression per unit area, but it is also dense. In transport applications, every kilogram of structural dead weight reduces legally permitted payload capacity. A steel truck body floor that weighs 400 kg more than a composite alternative costs the operator that payload on every journey. Over a vehicle’s working life, that lost payload translates directly into lost revenue.
Aluminium is lighter than steel but still significantly heavier than a composite sandwich panel of equivalent stiffness. Aluminium also corrodes in the presence of road salts and cleaning chemicals unless treated, adding maintenance cost over time. Composite thermoplastic panels are chemically inert to these environments and do not corrode.
For applications involving point loads or high-impact events, such as forklift traffic on a trailer floor, panel specification matters more than material category. A 4-ply glass-fibre skin on a 140 kg/m³ PP honeycomb core delivers meaningful point-load resistance. The right panel for a given application is always a function of load type, span, and support conditions, not a single material comparison.
What loads can sandwich panels realistically handle?
Sandwich panels can handle distributed loads, point loads, and dynamic loads when specified correctly for the application. The realistic load capacity depends on panel thickness, core density, skin layup, and the span between supports. Panels used in scaffolding, trailer floors, and truck body walls each face different load profiles, and the panel configuration should be matched to those profiles.
For scaffolding applications, the relevant European standard is EN 12811, which defines load classes for working platforms. A Compoform 10.5 mm panel has achieved EN 12811 load class 4 with no support underneath, a result from our own testing that demonstrates what a correctly specified thermoplastic sandwich panel can deliver in a regulated structural context.
For trailer and truck body floors, the governing loads are typically distributed loads from cargo and point loads from forklift wheels. These loads are applied dynamically, which means impact resistance matters alongside static strength. Thermoplastic composite skins absorb impact energy more effectively than brittle thermoset alternatives, which can crack under repeated dynamic loading.
For wall panels in cargo boxes and vehicle bodies, the primary loads are lateral pressure from cargo shifting in transit and wind loading at speed. These are bending-dominated loads, and sandwich panels are well suited to resist them across large unsupported spans, which is why they have largely replaced plywood and steel sheet in this application across European commercial vehicle manufacturing.
Does the core material affect structural performance?
Yes, the core material has a direct and significant effect on structural performance. The core controls shear stiffness, compressive strength, and resistance to point loads. Different core materials produce panels with meaningfully different structural characteristics, even when the skins are identical.
PP honeycomb cores provide high compressive strength relative to their weight. A 140 kg/m³ PP honeycomb core delivers strong resistance to point loads and concentrated pressure, relevant for flooring applications where forklift wheels or pallet feet apply load over a small area. The honeycomb geometry transfers load efficiently through the tube walls to the skins.
PP foam cores (oriented polypropylene foam) are available across a range of densities, from 40 kg/m³ to 140 kg/m³. Lower-density foam cores reduce panel weight and suit applications where distributed loads dominate and point-load resistance is less critical, such as wall cladding and cargo box sides. Higher-density foam cores approach honeycomb performance and suit applications with more demanding load requirements.
Core density is not the only variable. The orientation of the foam and the geometry of the honeycomb cells both influence how the core responds to shear forces. A panel under bending loads the core primarily in shear, so a core with high shear modulus will deflect less under the same load than a core with lower shear stiffness, even at the same density.
Are sandwich panels approved for use in regulated industries?
Sandwich panels can meet the requirements of regulated industries, but approval depends on the specific standard, the panel configuration, and the test evidence available. In European commercial vehicle manufacturing and scaffolding, the relevant standards are well established, and thermoplastic composite panels have been tested and qualified against them.
For scaffolding, EN 12811 defines the load classes that working platforms must achieve. Panels must be tested to demonstrate compliance with the relevant load class for the intended application. This is a formal qualification process, not a self-declaration.
For commercial vehicles, panels used in truck bodies and trailers must meet the structural and dimensional requirements of the vehicle type approval process. Wall panels, floor panels, and roof panels each carry different requirements, and the panel specification must be validated against those requirements before series production.
Fire performance is governed by EN 13501-1 in Europe. Panels used in applications where fire classification is required, including certain vehicle types and construction applications, must be tested to this standard. Flame-retardant additives can be incorporated into the skin formulation to achieve the required classification.
Recyclability is increasingly a compliance issue rather than a preference. The EU End-of-Life Vehicles (ELV) Directive sets requirements for the recyclability of materials used in vehicles, and thermoplastic composite panels are recyclable at end of life, an advantage over thermoset composites, which cannot be remelted and reprocessed.
When should you choose composite panels over traditional materials?
Composite sandwich panels make the strongest case when weight, durability, and total cost of ownership matter more than the lowest unit price. For truck body builders, trailer manufacturers, and scaffolding companies operating in Europe in 2026, those conditions apply in most procurement decisions.
Choose composite panels over steel or wood when:
- Payload capacity is a commercial priority. Every kilogram saved in body structure is a kilogram available for revenue-generating cargo. On a trailer operating daily over a 15-year vehicle life, the cumulative payload gain from a lighter body structure is substantial.
- Battery range matters. For electric trucks and vans, lighter body structures extend range per charge. In 2026, EV fleet buyers routinely ask about body weight as a range argument, not just a payload argument. Reducing structural dead weight directly increases the distance an electric vehicle can travel between charges.
- Replacement cycles add up. Plywood truck body floors typically last 3 to 5 years in heavy transport before requiring replacement. A thermoplastic composite floor lasts 12 or more years under the same conditions, eliminating two to three replacement cycles over a vehicle’s life. Once you account for panel cost, installation labour, and vehicle downtime, the composite is cheaper per year of service even at a higher unit price.
- Corrosion and moisture resistance are required. Composite panels do not rot, rust, or absorb water. For applications washed down regularly, truck floors, scaffolding boards, cargo box interiors, this removes a significant maintenance burden.
- Custom dimensions are needed. Standard steel sheet and plywood come in fixed sizes. Composite panels can be produced to custom dimensions, reducing fabrication time and waste in the assembly process.
Traditional materials retain an advantage where absolute strength under extreme point loads is required and weight is not a constraint, heavy industrial flooring under very high concentrated loads, for example. But for the majority of commercial vehicle and scaffolding applications, composite panels deliver a better combination of structural performance, weight, and service life.
How Compoform Supports Structural Panel Selection
We manufacture thermoplastic sandwich panels for commercial vehicles and scaffolding applications, using PP honeycomb and PP foam cores with glass-fibre-reinforced thermoplastic skins. Every panel configuration we produce is tested against the relevant European standards, including EN 12811 for scaffolding load classes and ISO 14125 for flexural performance.
When you bring us a structural application, we do not simply quote a standard panel. We review your load requirements, span conditions, and assembly process, then recommend the panel configuration that meets your structural specification without adding unnecessary weight or cost. Specifically, we can help you with:
- Selecting the right core type and density for your load profile
- Specifying skin layup and ply count to match your primary load direction
- Producing panels in custom dimensions up to 13,500 mm × 2,950 mm, cut to your exact specification
- Providing test data referenced to European standards so your engineering team can validate the specification
- Supporting you through integration, identifying potential issues before series production begins
A 30 mm PP sandwich panel floor, for example, is self-supporting, no aluminium subframe required. That removes a production step and reduces cost for truck body builders, which is the kind of application-level insight we bring to every project.
If you are evaluating composite panels for a structural application in commercial vehicles or scaffolding, speak with our structural panel engineering team. We will review your design, confirm the right panel configuration, and flag any integration considerations before you commit to production.