What payload gains are realistic when switching to sandwich panels?

Compoform · 24 Oct 2026

Switching from steel or plywood to thermoplastic sandwich panels can realistically save between 40% and 60% of the structural weight of a truck body or trailer body, depending on the panel configuration and the materials being replaced. For a standard curtainsider or dry freight trailer, that weight saving often translates directly into several hundred kilograms of additional legal payload. The questions below unpack how that weight saving works in practice, what it means for your bottom line, and where the gains are largest.

How much weight can composite sandwich panels actually save?

Thermoplastic sandwich panels are significantly lighter than the steel or plywood panels they replace. A 20 mm glass-fibre reinforced PP sandwich wall panel weighs around 2,930 g/m², while a comparable steel sheet or hardwood plywood panel of equivalent structural performance can weigh three to five times more per square metre. Across the full surface area of a truck body or trailer, that difference adds up quickly.

To put this in concrete terms: a standard 13.6-metre curtainsider trailer has roughly 80 to 100 m² of wall and floor surface. Replacing plywood walls with lightweight composite sandwich panels can remove 150 to 300 kg from the body structure, depending on the panel specification and the thickness of the original material. Floor panels contribute additional savings, though floor panels carry higher loads and use denser cores, so the weight reduction per square metre is smaller than for wall panels.

It is worth noting that not all sandwich panels weigh the same. A 17 mm wall panel with a 60 kg/m³ PP-foam core and a 2-ply skin weighs around 2,763 g/m², while a 30 mm floor panel with a 140 kg/m³ PP-honeycomb core weighs around 7,600 g/m². Panel selection should match the structural demand of each application, and the weight saving you achieve depends on which panels you are replacing and with which configuration.

How does payload capacity translate into revenue for operators?

Every kilogram saved in body structure is a kilogram that can be converted into legal, revenue-generating cargo. Under EU road transport regulations, most articulated trucks operate at a maximum gross vehicle weight of 44 tonnes. The lighter the vehicle structure, the more of that 44-tonne limit is available for freight. For operators running full loads, this is a direct revenue multiplier.

Consider a fleet operator running 250 days per year. If a lighter trailer body adds 300 kg of usable payload per trip, and the operator charges a freight rate based on weight or volume, that additional capacity compounds across every loaded journey. The commercial value depends on the freight type, the rate per tonne, and how consistently the vehicle runs at or near its gross weight limit. For high-density freight where weight limits are the binding constraint, the payload gain is immediately monetisable.

For electric truck operators, the calculation has an additional dimension. Lighter body structures extend battery range per charge. Every kilogram of structural dead weight reduces the distance an electric truck can travel on a single charge. In 2026, this is a standard procurement question from EV fleet buyers: how much does the body structure weigh, and what does that mean for operational range? Weight reduction is no longer just a payload argument for transport operators transitioning to electric vehicles. It is a range argument that directly affects route planning and charging infrastructure requirements.

What factors determine how much payload a panel switch delivers?

The payload gain from switching to sandwich panels depends on several variables, and the answer is not the same for every vehicle or application. The most important factors are the weight of the material being replaced, the surface area of the body, the panel configuration selected, and whether the switch also eliminates secondary structural components.

Material being replaced: Replacing steel delivers larger weight savings than replacing plywood. Replacing thick hardwood flooring with a composite floor panel delivers more savings than replacing a thin aluminium liner.
Body surface area: Larger vehicles have more surface area, so the weight saving per square metre multiplies across a bigger total. A 13.6-metre trailer body benefits more in absolute terms than a 7-metre van body.
Panel configuration: Thinner panels with lower-density cores weigh less. However, the panel must still meet the structural requirements of the application. Selecting the right configuration requires matching load demands to panel performance.
Elimination of subframes: A 30 mm PP sandwich floor panel is self-supporting and requires no aluminium subframe underneath. Removing the subframe adds further weight reduction beyond the panel itself, and also removes a production step for the body builder.
Number of panels switched: Replacing only the side walls delivers a partial gain. Replacing walls, roof, and floor delivers the full structural weight reduction.

Do sandwich panels maintain structural performance at lower weight?

Yes. Thermoplastic sandwich panels achieve their weight reduction through structural design, not by sacrificing strength. The sandwich construction places high-strength glass-fibre reinforced skins on either side of a lightweight core, creating a panel that resists bending loads efficiently without the mass of a solid material. The result is a high stiffness-to-weight ratio that solid steel or plywood cannot match.

The glass-fibre skins in Compoform’s panels contain 66 to 67% glass fibre by content and deliver tensile strength values that are consistent across the product range. The core material, whether PP-foam or PP-honeycomb, provides compressive resistance and shear transfer between the skins. The 140 kg/m³ PP-honeycomb core used in floor panels, for example, delivers a compressive strength sufficient for the point loads and distributed loads typical of truck body flooring.

Structural performance is also verified against European standards. Scaffold boards produced to this construction principle have achieved EN 12811 load class 4 with no support underneath, which is a demanding load requirement for access equipment. For truck body and trailer applications, panels are engineered to meet the specific floor load and wall load requirements of the vehicle type. The key point is that the structural case for composite panels is not theoretical. It is backed by test data referenced to European standards.

Which vehicle and trailer applications see the biggest payload gains?

The largest payload gains come from truck body and trailer applications across vehicle types where the body structure currently uses heavy materials across large surface areas, and where the vehicle regularly operates at or near its gross weight limit. Dry freight trailers, curtainsiders, and refrigerated van bodies are the applications where the weight saving from composite sandwich panels has the most direct commercial impact.

Dry freight and curtainsider trailers

These vehicles have large wall and floor surface areas, and they frequently carry dense freight where gross weight limits are the binding constraint. Replacing plywood or steel-lined walls with lightweight composite panels across a full 13.6-metre trailer body can deliver payload gains in the range of 200 to 400 kg, depending on the original specification. Floor panels add further savings, particularly when the composite floor eliminates the need for a separate aluminium subframe.

Refrigerated and insulated van bodies

Refrigerated bodies carry the additional weight of insulation and refrigeration equipment, which makes structural weight reduction even more valuable. Every kilogram saved in the body shell is a kilogram that can be added to the cold chain payload. Composite sandwich panels also offer thermal performance advantages that can reduce the thickness of additional insulation required, compounding the weight benefit.

Are there hidden costs that offset the payload gains from composite panels?

Composite sandwich panels typically carry a higher unit price than plywood or steel sheet. This is the most common objection raised during procurement. However, when you account for the full cost over a vehicle’s service life, the composite panel is consistently cheaper per year of use.

Thermoplastic composite panels last three to four times longer than plywood in heavy transport applications. In practical terms, a composite floor that lasts 12 or more years eliminates two to three plywood replacement cycles over the same period. Each replacement cycle involves panel cost, installation labour, and vehicle downtime. Once you add those costs together, the composite panel is cheaper per year of service even at a higher unit price.

There are also costs that do not appear on the panel invoice but affect total cost of ownership:

Maintenance and cleaning: Composite panels resist moisture, rot, and chemical contamination. Plywood floors absorb liquids, degrade under repeated wash-down, and require more frequent inspection and repair.
Fuel and energy savings: A lighter vehicle uses less fuel on diesel powertrains and extends range on electric powertrains. Over a fleet of vehicles running high annual mileage, this saving is material.
Downtime: A panel that does not need replacing for 12 years keeps the vehicle in service. Plywood replacement typically takes a vehicle off the road for one to several days per cycle.
Recyclability compliance: Under the EU End-of-Life Vehicles Directive, manufacturers face increasing pressure to use recyclable materials. Thermoplastic composite panels are recyclable at end of life. This is a compliance consideration for European OEMs, not just a preference.

The honest answer is that composite panels do cost more upfront. The hidden cost that operators often miss is the total cost of the alternative over the vehicle’s full service life.

How We Help You Maximise Payload Gains

We work with truck body builders and trailer manufacturers across Europe to identify the panel configuration that delivers the best combination of weight reduction, structural performance, and total cost of ownership for each specific application. This is not a catalogue selection exercise. It involves reviewing your current body design, understanding your load requirements, and engineering a panel specification that meets them.

Custom panel dimensions: Panels are available up to 13,500 mm × 2,950 mm, cut to your exact specification. This eliminates joins that add weight and assembly complexity.
Application-specific core selection: We match core density and skin architecture to the structural demands of each panel position, whether that is a lightly loaded wall panel or a self-supporting floor panel that replaces a subframe.
Pre-production engineering review: Before production starts, we review your design, flag potential integration issues, and confirm that the panel specification will perform as expected in your assembly process.
Ongoing support: We stay involved through integration, commissioning, and any issues that arise in service. Our role does not end when the panels ship.

If you are evaluating a switch from plywood or steel to composite sandwich panels and want to understand the realistic payload gain for your specific vehicle type, speak with our application engineers. We will review your current specification and give you a concrete answer based on your design, not a generic estimate.