Sandwich panel vs aluminium: which is lighter?

Compoform · 29 Jul 2026

Thermoplastic sandwich panels are significantly lighter than aluminium sheet of equivalent thickness. A well-specified composite sandwich panel can weigh less than half as much as a comparable aluminium panel, depending on the core material, the skin construction and the required thickness. The weight advantage is real, measurable and directly relevant to payload capacity and energy efficiency in commercial vehicle applications. The sections below address the questions buyers ask most often when comparing these two materials.

How much lighter are sandwich panels than aluminium?

A thermoplastic sandwich panel is typically 50 to 70% lighter than an aluminium panel with equivalent structural performance, depending on the core type and skin specification. Aluminium sheet used in truck bodies and trailer walls typically weighs between 10 and 15 kg per square metre at practical working thicknesses. A comparable composite sandwich panel, with a PP foam or PP honeycomb core and glass-fibre skins, can come in well under 10 kg per square metre.

To put this in concrete terms: Compoform’s 30 mm floor panel with a PP honeycomb core and 4-layer glass-fibre anti-slip skins has a measured areal weight of 7,600 g/m² (7.6 kg/m²), based on Compoform’s own ISO 14125 test data. A 30 mm aluminium plate would weigh approximately 81 kg/m² — an entirely different structural category. Even when comparing aluminium in thinner gauges used for body panels rather than structural plate, the composite panel retains a clear weight advantage.

The reason the comparison is not always straightforward is that aluminium and sandwich panels are rarely used at the same thickness for the same function. A sandwich panel achieves its stiffness by separating the skin layers with a lightweight core, not through material density alone. This means you are often comparing a 20 or 30 mm composite panel with a 3 to 5 mm aluminium sheet, where the composite still wins on weight while offering superior bending resistance.

What gives sandwich panels their structural strength despite the low weight?

Sandwich panels achieve high structural performance through geometry rather than mass. The skin layers carry tensile and compressive loads, while the lightweight core keeps them apart and resists shear forces. This separation effect greatly increases the panel’s bending stiffness relative to its weight — the same engineering principle that makes an I-beam stiffer than a solid bar with the same cross-sectional area.

In thermoplastic composite panels, the skin layers are glass-fibre reinforced laminates. The fibre orientation in those skins determines how the load is distributed. A cross-ply laminate, with fibres in the 0° and 90° directions, equalises the mechanical properties in both directions — useful for wall panels that can be mounted in either orientation. A unidirectional or multi-layer build concentrates strength along a primary load axis, which suits floor panels where the dominant load runs across the span.

The core material also contributes more than just separation. A PP honeycomb core of 140 kg/m³ offers meaningful compressive resistance, allowing floor panels with this core to take high point loads without deforming. Compoform’s tested 30 mm floor panel withstood an average maximum load of 5,647 N in standardised three-point bending (ISO 14125), without requiring an aluminium subframe beneath it. This self-supporting property removes a production step for truck body builders and further reduces the total system weight.

Where do weight savings actually matter in practice?

Weight savings from sandwich panels translate directly into payload capacity and energy efficiency in commercial vehicle and scaffolding applications. For truck bodies and trailers, every kilogram saved in the body structure is a kilogram that can be converted into revenue-generating cargo. In regulated freight markets, where the maximum permitted vehicle mass is fixed by law, structural dead weight is a direct cost.

In 2026, weight reduction brings a second argument that procurement teams at fleet operators and OEMs now consider just as important: the battery range of electric trucks and vans. Lighter body structures extend the range per charge. Every kilogram of structural dead weight reduces the distance an electric vehicle can travel on a single charge, which makes weight reduction a range argument, not just a payload argument. This is a standard question from EV fleet buyers, and it fundamentally changes the commercial calculation for composite panels. A lighter trailer body is not only more profitable on diesel; it is also more viable on electric.

For scaffolding applications, weight savings affect handling safety and assembly speed. Lighter scaffold floors reduce the physical strain on workers during erection and dismantling, which has a direct impact on productivity on site and compliance with lifting standards. A panel that meets the load class requirements of EN 12811 at a lower weight is not a compromise — it is a better product for the application.

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Are sandwich panels as durable as aluminium under demanding conditions?

In the conditions relevant to commercial vehicles and scaffolding, thermoplastic sandwich panels are equal to or better than aluminium in terms of durability. Aluminium is corrosion-resistant in most environments, but it is prone to fatigue cracking under repeated vibration loads, and it deforms permanently under impact. Thermoplastic composite panels absorb impact energy differently — the glass-fibre skins spread the load over a larger area, and the thermoplastic matrix is inherently resistant to corrosion, moisture and most cleaning chemicals.

In heavy transport applications, composite floor panels consistently outperform plywood by a considerable margin. Field experience with thermoplastic composite floors in truck bodies shows a service life of 12 years or more, compared with 3 to 5 years for plywood before replacement is needed. Over a vehicle lifetime of 15 years, that eliminates two or three replacement cycles. When you factor in panel costs, installation labour and vehicle downtime during replacement, the composite floor is cheaper per year of use — even at a higher unit price than plywood or thin aluminium sheet.

Edge finishing is a relevant factor in durability. Unprotected core edges are vulnerable to moisture ingress and UV degradation if they are not sealed. Correct edge sealing and edge bending protect the core in applications where panels are washed down regularly — truck floors and scaffold floors are the most obvious examples. A correctly specified and finished composite panel holds up under these conditions, without the corrosion risk that affects aluminium in salt or chemically aggressive environments.

What are the main drawbacks of aluminium panels compared with composites?

Aluminium panels have three practical drawbacks compared with thermoplastic sandwich panels in commercial vehicle and scaffolding applications: higher weight at equivalent stiffness, susceptibility to permanent deformation under impact, and limited recyclability under current European regulations.

Weight: Aluminium is a relatively heavy metal. To achieve the bending stiffness required for a truck floor or wall panel, considerable thickness or a subframe is needed — both of which add weight. A composite sandwich panel achieves comparable stiffness at a fraction of the mass.
Impact behaviour: Aluminium deforms plastically under impact. A dent or crease is permanent and often requires panel replacement. Glass-fibre composite skins distribute impact loads more broadly and are less susceptible to localised permanent deformation under the kinds of knocks typical of loading dock environments.
Recyclability compliance: The EU End-of-Life Vehicles (ELV) Directive and the broader Corporate Sustainability Reporting Directive (CSRD) require European OEMs to account for end-of-life material flows. Thermoplastic composite panels are fully recyclable — the thermoplastic matrix can be reprocessed, which is not the case with thermoset composites. For OEMs with CSRD reporting obligations, this is a compliance matter, not just a preference.
Thermal conductivity: Aluminium conducts heat efficiently, which is a disadvantage in applications with temperature-sensitive cargo. Sandwich panels with a foam or honeycomb core provide meaningful thermal insulation as part of their standard construction.

When should you choose sandwich panels over aluminium?

Choose sandwich panels over aluminium when payload capacity, energy efficiency or long-term total cost of ownership are the primary decision criteria. If your application has a fixed maximum vehicle mass, a composite body structure gives you more usable payload. If you operate electric vehicles, a lighter structure extends the range per charge. If you calculate costs over the full life of a vehicle rather than just the purchase price, composite panels typically win on TCO once replacement cycles are taken into account.

Sandwich panels are the better choice when:

You want to maximise payload within the legal maximum vehicle mass
You operate or supply EV fleets where structural weight directly affects range
Your application requires thermal insulation as part of the panel function
You need custom panel dimensions that are not available in standard aluminium sheet formats
A long service life and low maintenance matter more than the lowest possible unit price
Your OEM has CSRD or ELV Directive obligations that require recyclable materials

Aluminium remains a practical choice where very high point loads in a small area exceed the capacity of a composite panel without a subframe, or where fire performance requirements in a specific market segment favour metal. But for the majority of truck body, trailer and scaffolding applications in the European market, the structural, commercial and regulatory case for composite sandwich panels is strong and growing.

How does Compoform help you choose the right panel?

We work with truck body builders, trailer manufacturers and scaffolding companies across Europe to specify panels that match the actual load requirements, assembly process and operating conditions of each application — not just the nearest standard product.

This is what that looks like in practice:

Application analysis: We review your design and identify the load cases, span requirements and surface finish needs before recommending a panel configuration. Core density, skin construction and thickness are all variables we optimise for your specific use case.
Custom dimensions: Panels are available in custom sizes cut to your exact specification, up to 13,500 mm × 2,900 mm. Standard sheet formats are rarely the most efficient solution for a body builder or trailer manufacturer working with fixed vehicle dimensions.
Self-supporting floor panels: Our 30 mm PP honeycomb panel is self-supporting — no aluminium subframe required. This removes a production step and reduces system weight, which matters for both payload capacity and EV range in electric truck applications.
Edge finishing advice: We advise on edge sealing and edge bending for panels used in wash-down environments, so the core stays protected throughout the full service life of the vehicle or scaffold floor.
Long-term TCO support: We help you build the commercial case for composite panels internally, including service life data, replacement cycle calculations and weight savings that translate into payload or range arguments for your end customers.

If you are evaluating sandwich panels for a truck floor, trailer wall or scaffolding application, talk to our engineering team today. We will review your requirements, flag any integration considerations before production starts, and help you arrive at a panel specification that performs throughout the full service life of the application — not just on paper.