Sandwich panels increase payload capacity in trailers by replacing heavy steel or wood structural panels with lightweight composite alternatives that deliver equivalent or greater structural performance at a fraction of the weight. For a typical trailer body, switching from steel or plywood walls and floors to thermoplastic sandwich panels can free up several hundred kilograms of structural dead weight, weight that converts directly into additional legal cargo capacity per trip.
The benefit compounds across a vehicle’s working life. More payload per journey means more revenue per kilometre, and for fleet operators transitioning to electric trucks, lighter body structures also extend battery range per charge. The questions below unpack the mechanics, the materials, and the decision criteria trailer manufacturers need to evaluate.
How much weight do sandwich panels save compared to steel or wood?
Thermoplastic sandwich panels are significantly lighter than steel and meaningfully lighter than plywood. A glass-fibre-reinforced PP sandwich panel wall section typically weighs well under half the equivalent steel panel, and depending on thickness and core specification, can weigh less than a third. Compared to plywood, weight savings of 30 to 50 percent are achievable depending on the panel configuration selected.
The reason lies in the sandwich construction itself. A lightweight core material, either a PP honeycomb or a PET foam, sits between two thin, high-strength glass-fibre-reinforced thermoplastic skins. The core separates the skins to create a high second moment of area, which is what gives the panel its bending stiffness. You get structural rigidity without the mass that comes with solid steel or timber.
For a full trailer body, side walls, roof, and floor, the cumulative weight difference is substantial. Trailer body builders who have moved from steel side panels to thermoplastic sandwich panels report body weight reductions that translate directly into additional payload headroom under European gross vehicle weight regulations. Every kilogram removed from the body structure is a kilogram that can carry revenue-generating cargo instead.
How does reducing trailer dead weight increase legal payload?
European road transport regulations set a maximum gross vehicle weight (GVW) for each vehicle category. The legal payload a trailer can carry is the GVW minus the vehicle’s unladen weight, the tare. Reduce the tare by making the body structure lighter, and the legal payload increases by exactly the same amount. A 300 kg reduction in body weight means 300 kg more cargo per trip, within the same legal limit.
At scale, this matters considerably. A fleet running 250 days per year, with even a modest increase in payload per journey, accumulates a meaningful revenue advantage over a competitor operating heavier bodies. The economics are straightforward: structural dead weight is wasted GVW allowance.
For electric truck operators, the argument extends beyond payload. Lighter body structures reduce the total mass the drivetrain must move, which directly extends battery range per charge. In 2026, EV fleet buyers routinely raise body weight as a range question during procurement, not just a payload question. A lighter trailer body means more kilometres per charge cycle, which affects route planning, charging infrastructure requirements, and total operating cost. Weight reduction in the body structure is therefore a dual commercial argument: more cargo capacity and more range.
What types of sandwich panels are used in trailer construction?
Trailer construction uses sandwich panels in three primary structural zones: side walls, the roof, and the floor. Each zone has different load requirements, and the panel specification, core material, core density, skin architecture, and thickness, is selected accordingly. You can explore sandwich panel applications across commercial vehicle sectors to see how specifications vary by use case.
Wall and roof panels
Side wall and roof panels in trailer bodies prioritise low weight and weather resistance over compressive strength. Panels using an oriented PP foam core with glass-fibre-reinforced thermoplastic skins in a cross-ply architecture are well suited here. The cross-ply layup, fibres oriented at 0° and 90° in alternating layers, equalises mechanical properties in both directions, so the panel performs consistently regardless of installation orientation. A white PET-film surface finish provides UV resistance and a clean interior appearance without additional lining.
Floor panels
Trailer floors carry concentrated point loads from forklift tyres, pallet feet, and cargo shifting in transit. This demands higher compressive and bending performance than wall panels. PP honeycomb cores at higher densities, combined with 4-ply glass-fibre skins, deliver the load-bearing capacity needed. A black anti-skid surface finish is standard for floor applications, providing grip without additional treatment. A 30 mm PP honeycomb floor panel is self-supporting; it does not require an aluminium subframe beneath it, which removes a production step and reduces assembly cost for trailer manufacturers.
Do sandwich panels hold up to the structural demands of trailers?
Yes, when correctly specified, thermoplastic sandwich panels meet the structural demands of trailer construction across all primary load cases. The key word is “specified”: panel performance varies with core density, skin thickness, skin architecture, and overall panel thickness. A panel selected for a wall application will not be the right specification for a floor, and vice versa.
Bending performance is tested to ISO 14125, and tensile properties to EN ISO 527, the European standards relevant to this market. Compoform’s own floor panel test data shows that a 30 mm PP honeycomb floor panel sustains an average maximum load of 5,647 N in the tested geometry, compared to 3,240 N for a 15 mm variant. This gives trailer manufacturers a concrete reference point when evaluating whether a given panel configuration meets their floor load specification.
Durability in service is also a practical consideration. Thermoplastic sandwich panels last significantly longer than plywood in heavy transport applications, industry experience with composite floors in trailer and truck body applications points to service lives of 12 years or more, compared to 3 to 5 years for plywood before replacement is needed. Over a 15-year vehicle life, that eliminates two to three plywood replacement cycles. Once you account for panel cost, installation labour, and vehicle downtime during replacement, the composite floor is cheaper per year of service, even at a higher unit price.
What’s the difference between thermoplastic and thermoset composite panels for trailers?
The core distinction is in the polymer matrix used to bind the glass fibres in the skins. Thermoplastic panels use a matrix, typically polypropylene, that can be remelted and reformed. Thermoset panels use a resin system, such as polyester or epoxy, that cures irreversibly and cannot be reprocessed. This difference has practical consequences for trailer manufacturers across several dimensions.
Recyclability: Thermoplastic panels are recyclable at end of vehicle life. The EU End-of-Life Vehicles (ELV) Directive places increasing obligations on vehicle manufacturers to demonstrate recyclability of components. Thermoplastic composite panels support compliance with this requirement in a way that thermoset panels do not. For European OEMs subject to CSRD sustainability reporting, this is a compliance consideration, not just a preference.
Impact resistance: Thermoplastic matrices absorb impact energy more effectively than brittle thermoset resins. In trailer applications, where panels are exposed to forklift contact, load shifting, and road debris, this translates to better resistance to cracking and delamination in service.
Processing and joining: Thermoplastic panels can be welded, bent, and thermoformed using heat. Thermoset panels cannot. For trailer body builders who need edge bending, corner forming, or welded joints, thermoplastic panels offer fabrication options that thermoset materials do not.
Note: This article covers the broader sandwich panel market. Our range is limited to PP honeycomb and PET foam cores for commercial vehicles and scaffolding; we do not supply thermoset or FRP panels.
When should trailer manufacturers switch from metal to composite panels?
The switch from metal to composite sandwich panels makes commercial sense when payload efficiency, total cost of ownership, or end-of-life recyclability requirements are driving procurement decisions, and when production volumes are consistent enough to justify specifying a custom panel configuration.
Specific triggers that indicate the switch is worth evaluating include:
- Payload pressure: If your customers are operating close to GVW limits and losing revenue to body dead weight, composite panels directly address the problem.
- EV fleet transition: If your customers are moving to electric trucks or vans, body weight affects range per charge. EV fleet buyers in 2026 treat body weight as a range specification, not just a payload specification.
- Plywood replacement cycles: If your current floor specification requires replacement every three to five years, the lifecycle cost of composite floors is likely lower over the vehicle’s full service life.
- Regulatory compliance: If your OEM customers are subject to EU ELV or CSRD reporting requirements, thermoplastic composite panels support recyclability claims that metal and thermoset panels do not.
- Custom dimension requirements: If standard off-the-shelf panel sizes do not fit your body design, a manufacturer capable of producing panels to your exact dimensions removes the compromise.
The switch does not need to be all-or-nothing. Many trailer manufacturers begin with composite floors, where the payload and durability arguments are strongest, and extend to walls and roofs in subsequent model iterations as they gain confidence in the material and the supply relationship.
How Compoform Helps Trailer Manufacturers Increase Payload
We work with trailer manufacturers and truck body builders across Europe to specify and produce thermoplastic sandwich panels that replace steel, aluminium, and plywood in body structures. Our panels use PP honeycomb or PET foam cores with glass-fibre-reinforced thermoplastic skins, and every panel is made to order, you specify the core thickness, core density, skin architecture, and surface finish for your application.
What this means in practice for trailer manufacturers:
- Custom dimensions up to 13,500 mm × 2,950 mm: Panels cut to your exact body dimensions, eliminating joints and reducing assembly time.
- Self-supporting floor panels: Our 30 mm PP honeycomb floor panels do not require an aluminium subframe, removing a production step and reducing body weight further.
- Application review before production: We review your design, assess load requirements against panel configuration options, and flag any integration issues before a panel goes into production. You are not ordering from a catalogue, you are working with engineers who understand trailer body construction.
- Lifecycle support: We support you through integration, any issues that arise in service, and specification changes as your body designs evolve.
If you are evaluating a switch from steel or plywood in your trailer body, or if your customers are asking about payload efficiency or EV range, bring us your trailer body design. We will review the load requirements, recommend the right panel configuration, and give you a clear picture of the weight saving and TCO impact before you commit to a specification change.