Motorhome manufacturers are switching to sandwich panel walls because they deliver a better combination of structural performance, thermal insulation, and weight reduction than any traditional single-material wall can match. A sandwich panel replaces timber framing, plywood sheeting, insulation batts, and interior cladding with a single engineered component that does all of those jobs at once. The questions below unpack the specific advantages, material options, and sourcing considerations that matter most to motorhome and leisure vehicle builders in 2026.
What advantages do sandwich panels offer over traditional motorhome wall materials?
Sandwich panels outperform traditional motorhome wall materials by combining structural rigidity, thermal insulation, and a finished surface in a single panel, eliminating the layered build-up of timber frames, insulation, and cladding. This reduces assembly time, lowers vehicle weight, and produces a more consistent wall structure across every unit produced.
Traditional motorhome walls are typically built up from multiple components: a timber or aluminium frame, a layer of rigid foam insulation, an exterior skin, and an interior decorative panel. Each layer adds weight, each joint is a potential source of moisture ingress, and the overall assembly is labour-intensive. Sandwich panels replace this stack with a single pre-engineered component that arrives ready to cut and fit.
The structural advantages are significant. A well-specified sandwich panel wall resists racking, flexing, and vibration loads that a timber-framed wall handles poorly over time. Timber frames can warp, swell, and delaminate when exposed to the moisture cycles that motorhomes experience across seasons. Composite sandwich panels are dimensionally stable and do not absorb moisture in the way that wood-based materials do.
From a manufacturing perspective, the shift to sandwich panels also simplifies the production line. Builders work with a single material rather than coordinating multiple suppliers for framing, insulation, and cladding. Panel dimensions can be specified to match the exact geometry of the vehicle body, reducing on-site cutting and waste.
How much weight can motorhome builders save by switching to sandwich panels?
The weight saving from switching to sandwich panel walls depends on the panel specification and what it replaces, but replacing a timber-framed wall assembly with a glass-fibre-skinned thermoplastic sandwich panel typically delivers a meaningful reduction in structural dead weight. The exact saving varies by panel thickness, core density, and skin architecture.
Oriented PP-foam cores, for example, are available in densities from 40 to 140 kg/m³, which means the core weight can be tuned to the structural demand of the application. A wall panel using a 60 kg/m³ PP-foam core with cross-ply glass-fibre skins is substantially lighter than an equivalent timber-framed assembly while delivering greater bending stiffness and better insulation.
For motorhome builders, weight reduction matters on two levels. First, it directly affects the gross vehicle weight rating and what the vehicle can legally carry. Every kilogram saved in the body structure is a kilogram available for equipment, water, and personal load. Second, as electric motorhomes and leisure vehicles enter the market, lighter body structures extend battery range. Every kilogram of structural dead weight reduces range per charge, which is becoming a standard specification question from buyers considering electric leisure vehicles in 2026. Weight reduction is no longer just a payload argument; it is a range argument.
What are sandwich panels made of in motorhome construction?
Sandwich panels used in motorhome construction consist of a lightweight core material bonded between two structural skins. The core provides thickness and insulation; the skins carry the structural loads. The most common skin materials in thermoplastic composite panels are glass-fibre-reinforced polypropylene laminates, which offer a good balance of stiffness, impact resistance, and low weight.
Core materials vary across the broader market. This article covers core types found across the sandwich panel market; our range of motorhome and vehicle applications is limited to PP honeycomb and PET foam cores for commercial vehicles and related transport applications.
Core options and what they offer
PP-foam cores are available in multiple density grades, which allows the panel to be tuned for the specific structural and insulation demands of the application. Lower-density foam cores prioritise insulation and minimum weight; higher-density grades add compressive and shear strength for panels that carry greater loads.
PP-honeycomb cores offer higher structural performance than foam at comparable thickness, making them better suited to floor panels and load-bearing applications. For wall panels, a foam core at the right density is typically the more efficient choice because it also contributes to thermal resistance.
Skin architecture and surface finish
The skin architecture determines how the panel handles loads in different directions. A cross-ply laminate, with fibres oriented at 0 and 90 degrees in alternating layers, distributes mechanical properties evenly in both directions. This makes the panel suitable for installation in either orientation, which simplifies design and reduces the risk of assembly errors on the production line.
Surface finishes on wall panels can include a white PET-film, which provides a decorative, cleanable interior surface without any additional lining. This finish has a whiteness index of 84 and has been tested to over 22,000 hours of UV resistance, based on Compoform’s own testing data. For motorhome interiors, this means the panel can serve as the finished wall surface, removing another production step.
How do sandwich panels perform in terms of insulation and weather resistance?
Sandwich panels perform well in terms of both insulation and weather resistance, which is why they suit motorhome applications where the wall must manage temperature differentials across seasons and withstand years of outdoor exposure. The foam core provides thermal resistance, while the composite skins seal the structure against moisture and UV degradation.
Thermal conductivity in sandwich panels is primarily a function of core material and thickness. PP-foam cores have low thermal conductivity, and increasing panel thickness improves the overall thermal resistance of the wall without adding proportionally more weight. This makes it straightforward to specify a panel that meets the thermal performance target for a given climate zone.
Weather resistance is driven by the skin material and surface finish. Glass-fibre-reinforced thermoplastic skins do not corrode, do not absorb moisture, and do not degrade in the way that timber-based materials do when exposed to repeated wetting and drying cycles. A PET-film surface finish adds a further layer of UV protection. Panels tested to ISO 4892 UV weathering protocols confirm that the surface colour and gloss properties remain stable over extended outdoor exposure, which matters for exterior wall panels that face direct sunlight across the vehicle’s service life.
Unlike timber-framed walls, composite sandwich panels do not provide pathways for moisture to travel from the exterior to the interior. There are no timber members that can wick water through capillary action, and the panel edges can be sealed to prevent any moisture ingress at cut faces. This structural integrity over time is one of the strongest arguments for composite walls in leisure vehicles, where damp-related damage is a well-documented long-term problem with traditional construction.
What should motorhome manufacturers look for when sourcing sandwich panels?
When sourcing sandwich panels for motorhome wall construction, manufacturers should evaluate five factors: dimensional capability, core and skin specification flexibility, surface finish quality, supplier reliability, and post-sales technical support. Getting any one of these wrong creates production problems that are difficult and expensive to resolve mid-programme.
- Dimensional capability: Motorhome body panels are large. A supplier that can only produce standard sheet sizes forces you to join panels, which adds weight, complexity, and potential weak points. Look for a supplier capable of producing panels in the full dimensions your body design requires.
- Specification flexibility: Wall panels, floor panels, and roof panels have different structural and insulation demands. A supplier with a fixed product range cannot optimise for each application. Core density, skin ply count, and layer orientation should all be adjustable to your specification.
- Surface finish quality: If the panel surface serves as the finished interior wall, the colour consistency, gloss level, and UV stability of that finish need to be controlled and documented. Ask for test data, not just a sample.
- Supplier reliability: Panel supply interruptions stop your production line. European-made panels with predictable lead times and consistent quality reduce this risk compared to sourcing from distant markets where logistics and quality control are harder to manage.
- Technical support: Panel integration into a vehicle body involves edge details, fixing methods, and junction design. A supplier who can advise on these details before production starts prevents costly rework later.
It is also worth considering the recyclability of the panel material. Thermoplastic composite panels are recyclable at end of life, which is relevant for European OEMs operating under the EU End-of-Life Vehicles Directive. As CSRD sustainability reporting requirements expand, being able to document the recyclability of structural materials is becoming a procurement consideration, not just a preference.
How We Help Motorhome and Leisure Vehicle Manufacturers
We work with motorhome and coachbuilding manufacturers to specify, produce, and integrate thermoplastic sandwich panels that replace traditional timber-framed wall assemblies. Our approach starts with your design, not a standard catalogue.
- Custom panel dimensions: Our production line produces panels up to 13,500mm x 2,950mm, which means we can match the exact geometry of your body panels without forcing you to join smaller sheets.
- Specification support: We review your structural and thermal requirements and recommend the right core density, skin architecture, and surface finish for each panel in the vehicle. Wall panels, floor panels, and roof panels each get a configuration optimised for their specific load and environment.
- Finished interior surfaces: Our wall panels with white PET-film surfaces arrive with a finished decorative face, removing the need for a separate interior lining step in your assembly process.
- European manufacturing: All panels are produced at our facilities in Beek and Ospel, the Netherlands. This gives you predictable lead times, consistent quality, and direct access to our engineering team when questions arise during integration.
- Long-term partnership: We stay involved after the first delivery. If your design evolves, your production process changes, or you encounter a fit or performance issue, we work through it with you rather than treating the order as closed.
If you are evaluating sandwich panels for a new motorhome programme or looking to replace an existing wall construction, speak with our engineering team directly. We will review your design, identify where composite panels can reduce weight and assembly complexity, and confirm the right specification before any material is produced.