Sandwich panels reduce payload dead weight by replacing dense structural materials like steel and wood with a lightweight composite construction: two thin, high-strength skins bonded to a low-density core. The result is a panel that carries structural loads at a fraction of the mass. For truck body builders and trailer manufacturers, this directly converts dead weight into legal payload capacity.
The weight advantage is not marginal. A thermoplastic sandwich panel wall section can weigh less than 3 kg per square metre, compared to steel sheet or plywood that can exceed 10 to 15 kg per square metre at equivalent thicknesses. The sections below work through the mechanics, materials, and real-world implications of that difference.
What makes sandwich panels lighter than steel or wood?
Sandwich panels achieve low weight through their layered structure: two thin, stiff skins separated by a lightweight core. The core carries almost no in-plane load but holds the skins apart, which dramatically increases bending stiffness without adding proportional mass. This is the same structural principle as an I-beam, applied across a flat panel surface.
Steel derives its stiffness from mass. To make a steel panel stiffer, you add thickness, and thickness adds weight. Wood behaves similarly. A sandwich panel decouples stiffness from mass by using geometry rather than material density to resist bending forces.
The core material is where the weight saving is most pronounced. A PP-foam core at 60 kg/m³ is a fraction of the density of steel (around 7,800 kg/m³) or even structural plywood (around 600 kg/m³). The glass-fibre reinforced thermoplastic skins add strength and rigidity, but their thinness keeps the overall panel weight low. A 17 mm wall panel with a PP-foam core and glass-fibre skins, for example, weighs around 2,763 g/m² based on Compoform’s own product testing, under 3 kg per square metre for a structural panel.
How does panel weight directly affect payload capacity?
Every kilogram of structural dead weight in a truck body or trailer is a kilogram that cannot be loaded as cargo. In commercial transport, vehicles operate under legally defined gross vehicle weight (GVW) limits. The body structure, floor, walls, and roof all count against that limit before a single kilogram of freight is loaded.
Reducing the weight of the body structure by switching from steel or plywood to sandwich panels increases the available payload by an equivalent amount. For a full trailer with 60 to 80 square metres of wall and floor surface, switching from plywood to thermoplastic sandwich panels can free up a meaningful portion of the legal payload allowance. That translates directly into more freight per trip, or fewer trips for the same freight volume.
In 2026, weight reduction carries a second argument that procurement teams at EV fleet operators raise consistently. Lighter body structures extend battery range in electric trucks and vans. Every kilogram of structural dead weight reduces range per charge. For operators running electric vehicles, a lighter body is not just a payload argument, it is a range argument. EV fleet buyers now treat panel weight as a direct input to their range calculations, and this is a standard procurement question in commercial vehicle tenders.
Which sandwich panel materials offer the best weight-to-strength ratio?
For commercial vehicle and scaffolding applications, glass-fibre reinforced thermoplastic skins over a PP-foam or PP-honeycomb core deliver the strongest weight-to-strength ratio among available panel constructions. The skins provide high tensile strength, while the core keeps overall panel density low.
The right combination depends on the load demands of the application:
- PP-foam core panels at 60 kg/m³ are well suited to wall cladding and non-structural enclosure panels. A 17 mm wall panel weighs around 2,763 g/m² while maintaining the bending performance needed for truck body side walls.
- PP-honeycomb core panels at 140 kg/m³ are used where compressive and bending loads are higher, such as floor panels. A 15 mm floor panel weighs around 5,550 g/m², and a 30 mm floor panel around 7,600 g/m², heavier than wall panels, but substantially lighter than steel or hardwood flooring at equivalent structural performance.
- Skin architecture also affects the balance. Cross-ply laminates distribute strength equally in both directions, which suits panels that may be installed in either orientation. Multi-ply unidirectional skins concentrate strength along a primary axis, which suits floor panels where the dominant load direction is consistent.
Glass content in the skins runs at 66 to 67% by weight based on Compoform’s product testing, which is a high fibre fraction that keeps the skin thin while maintaining tensile performance. The result is a panel family where structural capability scales with thickness and core density, without the weight penalty that comes with solid materials.
What applications benefit most from lightweight sandwich panels?
Applications where structural weight directly costs money or performance benefit most from lightweight sandwich panels. The two clearest cases in 2026 are commercial vehicle bodies and scaffolding platform applications.
Truck bodies and trailers are the primary application. Floor panels, side walls, and roof panels all contribute to body dead weight. Replacing plywood floors with thermoplastic sandwich panels removes weight from the heaviest surface in the body. A 30 mm PP-honeycomb floor panel is self-supporting, no aluminium subframe is required underneath it. This removes a production step for the body builder and eliminates the weight of the subframe itself.
Scaffolding boards benefit because workers carry and reposition boards repeatedly across a working day. A lighter board reduces physical strain and speeds up erection and dismantling. An 11 mm Compoform scaffolding panel weighs around 4,310 g/m², and the skin layup is specifically oriented to maximise transverse strength, the direction that matters when a board spans between standards and carries point loads from workers and materials.
Other applications where weight reduction delivers measurable benefit include cargo boxes, horse vans, caravans, and mobile homes, any enclosed structure mounted on a vehicle chassis where body weight competes directly with payload or range.
How do sandwich panels compare to aluminium panels for weight savings?
Aluminium sheet is lighter than steel but heavier than a well-specified thermoplastic sandwich panel at equivalent structural performance. Aluminium has a density of around 2,700 kg/m³. A structural aluminium panel thick enough to match the bending stiffness of a 17 mm sandwich panel will typically be heavier per square metre than the composite alternative.
The more important comparison is not just weight per square metre, but weight per unit of structural performance. Sandwich panels achieve high bending stiffness through their geometry, the separation of the skins by the core, rather than through material density. This means a sandwich panel can match or exceed the bending performance of an aluminium sheet at lower areal weight.
Aluminium also has practical limitations in transport body construction. It requires welding or riveting for joints, it is susceptible to fatigue cracking at stress concentrations, and it does not absorb impact energy as effectively as a fibre-reinforced composite. Thermoplastic sandwich panels can be cut to custom dimensions, edge-sealed to protect the core from moisture and wash-down cycles, and joined using adhesive bonding, which distributes load across the joint rather than concentrating it at fastener points.
For fleet operators running vehicles through regular pressure washing, edge sealing on composite panels is a practical durability advantage that aluminium sheet does not require but also does not provide.
Can sandwich panels maintain structural integrity at reduced weight?
Yes. Sandwich panels maintain structural integrity at reduced weight because their strength comes from geometry and material architecture, not from mass. The skins carry tensile and compressive loads; the core resists shear and keeps the skins in position. This division of function allows each component to be optimised independently.
Structural performance is verified against European standards. For scaffolding, EN 12811 defines load classes for working platforms. A 10.5 mm Compoform panel has achieved EN 12811 load class 4 with no support underneath, a demanding structural requirement for a panel of that thickness. For floor panels, bending performance is tested to ISO 14125, and compressive core performance is tested to EN ISO 844.
Thermoplastic sandwich panels also have a durability advantage over the materials they replace. In heavy transport applications, a composite floor panel lasts significantly longer than plywood under the same conditions. Industry experience in commercial vehicle applications indicates composite floors outlast plywood by a factor of three to four, meaning a composite floor installed once can outlast two or three plywood replacement cycles over a vehicle’s working life. Over a 15-year vehicle life, that eliminates two to three replacement events, each of which carries panel cost, installation labour, and vehicle downtime. At a higher unit price, the composite is cheaper per year of service.
Impact resistance is a further consideration. Compoform’s continuous fibre-reinforced tape technology generates 50% higher impact resistance compared to standard composite materials based on Compoform’s own testing, relevant for floor panels and cargo box walls that take repeated loading and unloading impacts.
How Compoform Helps You Reduce Structural Dead Weight
We design and manufacture thermoplastic sandwich panels specifically for commercial vehicle bodies and scaffolding applications. Our panel range uses PP-foam and PP-honeycomb cores with glass-fibre reinforced thermoplastic skins, produced at our facilities in Beek and Ospel, the Netherlands.
When you bring us a body-building or platform application, here is what the process looks like in practice:
- Application review: We review your design, load requirements, and assembly process before recommending a panel configuration. Core density, skin architecture, and panel thickness are matched to your specific structural and weight targets, not selected from a generic catalogue.
- Custom dimensions: Panels are available in custom dimensions cut to your exact specification, up to 13,500 mm × 2,950 mm. This eliminates on-site cutting waste and reduces assembly time.
- Edge sealing and protection: Edge sealing and edge bending are available to protect the core from UV exposure and moisture, relevant for truck floors and scaffolding boards that are washed down regularly.
- Self-supporting floor panels: Our 30 mm PP-honeycomb floor panels are self-supporting, removing the need for an aluminium subframe and reducing both weight and production steps for body builders.
- EV fleet compatibility: If you are supplying body structures for electric truck platforms, we can help you quantify the weight saving and its effect on range, a calculation that EV procurement teams increasingly require from their body builder suppliers.
We do not ship panels to spec and step back. We stay involved through integration, flag issues before they reach production, and support you through iteration as your design evolves. If you are replacing steel, plywood, or aluminium in a truck body or trailer application and want to understand what the weight and TCO numbers look like for your specific configuration, speak with our engineering team directly.