How do sandwich panels improve thermal insulation in RVs?

compoform · 11 Sep 2026

Sandwich panels improve thermal insulation in RVs by combining a low-conductivity core material with rigid outer skins, creating a composite wall that resists heat transfer far more effectively than solid timber, aluminium, or fibreglass alone. The insulating core does the thermal work, while the skins provide structural strength, keeping the total wall thickness and weight low. The sections below unpack the specific mechanisms, core material choices, and practical performance benchmarks that matter most for RV builders and buyers.

What makes sandwich panels more insulating than traditional RV wall materials?

Sandwich panels outperform traditional RV wall materials because their core layer is specifically designed to trap air or gas within a closed or semi-closed structure, dramatically slowing the movement of heat. Solid wood, aluminium sheet, and even basic fibreglass all conduct heat relatively freely. A sandwich panel replaces that conductive mass with a lightweight core that interrupts the thermal path between the interior and exterior surfaces.

Traditional RV walls built from timber framing with fibreglass skins rely on the insulation stuffed between structural members, which creates thermal bridges wherever the frame contacts the skin. A sandwich panel eliminates those bridges by making the insulating core continuous across the full panel area. Heat has no direct structural path from one face to the other.

The result is a wall that is simultaneously lighter, thinner for a given insulation level, and more consistent in its thermal performance across the entire surface. For RV manufacturers, this translates into a simpler build process, fewer components, and a finished vehicle that holds interior temperature more reliably in both summer and winter conditions.

How does the core material affect thermal performance in sandwich panels?

The core material is the primary driver of a sandwich panel’s thermal performance. Different core types conduct heat at different rates, measured as thermal conductivity under standards such as EN 12667. A lower conductivity value means the core resists heat flow more effectively, keeping warmth inside during cold weather and blocking solar heat gain in summer.

Foam cores

Foam cores, such as oriented polypropylene (PP) foam, work by trapping millions of tiny air pockets within a polymer matrix. Air is a poor conductor of heat, so the foam structure slows thermal transfer significantly. PP foam is available across a range of densities, and lower-density grades generally offer better thermal resistance because they contain a higher proportion of trapped air relative to solid polymer. For RV wall panels, a foam core in the 40 to 60 kg/m³ range typically delivers strong insulation performance while keeping panel weight low.

Honeycomb cores

Honeycomb cores, such as PP honeycomb, use a tubular or hexagonal cell geometry to achieve structural rigidity with minimal material. The air columns within the cells provide some thermal resistance, but honeycomb cores are primarily optimised for load-bearing performance rather than insulation. In RV and leisure vehicle panel applications, honeycomb cores are better suited to floors and structural panels where compressive strength matters more than thermal resistance. For walls and ceilings where insulation is the priority, a foam core is the more appropriate choice.

Core thickness also matters. A thicker core of the same material will always deliver better insulation than a thinner one, so RV builders need to balance the thermal target against the available wall depth and the overall weight budget of the vehicle.

What R-value should RV sandwich panels have for year-round use?

For year-round RV use across European climates, wall sandwich panels should target a thermal resistance (R-value) sufficient to maintain comfortable interior temperatures in both winter cold and summer heat without excessive heating or cooling load. While exact requirements vary by climate zone and intended use, industry experience with leisure vehicle construction suggests that well-specified foam-core sandwich panels in the 20 to 30 mm thickness range deliver meaningful insulation performance for three-season and mild four-season use.

It is worth noting that R-value alone does not tell the full story. A panel with a high R-value but poor edge sealing or joints that allow air infiltration will underperform in practice. The thermal performance of the finished RV wall depends on the panel specification, the joint design, and the quality of installation. Specifying the right panel is the starting point, not the complete solution.

For RV builders targeting colder climates or winter camping markets, increasing core thickness and selecting a lower-density foam core are the most direct ways to improve thermal resistance without adding significant weight. Consulting thermal conductivity data measured to EN 12667 for the specific panel configuration you are considering gives you a reliable basis for comparison across suppliers.

How do sandwich panels prevent condensation inside RVs?

Sandwich panels reduce condensation risk inside RVs by keeping the interior wall surface warmer than a poorly insulated wall would be. Condensation forms when warm, moist interior air contacts a surface that has dropped below the dew point temperature. A well-insulated sandwich panel wall holds its interior surface temperature closer to the cabin air temperature, reducing the likelihood of that threshold being crossed.

The continuous, uninterrupted core of a sandwich panel is particularly valuable here. Traditional timber-framed walls create cold spots at every stud or frame member, because the structural timber conducts heat away from the interior surface faster than the insulation between members does. These cold spots are where condensation tends to appear first, leading to moisture damage, mould, and deterioration of the wall structure over time.

Thermoplastic sandwich panels also have an advantage in moisture resistance at the material level. Unlike timber, a polypropylene foam or honeycomb core does not absorb water. If moisture does reach the core through a joint or damaged edge, it does not cause the swelling, rot, or structural degradation that wood-based panels suffer. This makes the long-term performance of the wall more predictable and the maintenance burden lower over the vehicle’s life.

Are thermoplastic sandwich panels better than fibreglass for RV insulation?

Thermoplastic sandwich panels and fibreglass panels serve different functions, so the comparison depends on what you mean by “fibreglass.” A fibreglass skin on a sandwich panel is a structural facing material, not an insulator. The insulation comes from the core. A thermoplastic sandwich panel with a glass-fibre-reinforced PP skin and a foam core will outperform a simple fibreglass sheet with no insulating core, because the panel has a dedicated thermal layer and the fibreglass sheet does not.

Where thermoplastic sandwich panels offer a genuine advantage over older fibreglass-based RV construction is in the combination of properties they deliver in a single component. A well-specified thermoplastic panel provides structural rigidity, thermal insulation, moisture resistance, and a finished surface in one panel, reducing the number of layers and materials a builder needs to assemble. Fibreglass-over-timber or fibreglass-over-foam constructions built up on-site introduce more joints, more potential failure points, and more variability in the finished result.

Thermoplastic panels also offer a recyclability advantage that is increasingly relevant for European RV and leisure vehicle manufacturers. As sustainability requirements tighten under EU regulations, the ability to recycle thermoplastic composite panels at end of life is a practical compliance consideration, not just a marketing point. Thermoset fibreglass composites are significantly harder to recycle and are facing growing regulatory scrutiny in European markets.

How Compoform Helps with Sandwich Panel Insulation for RVs and Leisure Vehicles

We manufacture thermoplastic sandwich panels using PP foam and PP honeycomb cores, and we work with RV and leisure vehicle builders to specify the right panel configuration for their application. For wall panels where thermal insulation is the priority, we use oriented PP foam cores in densities from 40 to 140 kg/m³, allowing us to tune the balance between insulation performance, structural stiffness, and panel weight to match your exact design requirements.

Here is what working with us on a panel specification looks like in practice:

Core selection: We review your wall thickness constraints and thermal targets, then recommend the foam density and panel thickness that achieves the insulation level you need without unnecessary weight.
Skin architecture: We select the skin layup, whether cross-ply or multi-ply glass-fibre-reinforced PP, based on the structural loads your panels need to carry in service.
Surface finish: Wall panels are available with a white PET-film surface finish that provides a ready-to-use interior face with controlled colour properties and over 22,000 hours of UV resistance, based on our own testing.
Custom dimensions: Panels are produced up to 13,500 mm × 2,950 mm, cut to your specification, so you are not working around standard sheet sizes.
Edge protection: We advise on edge sealing and edge bending to protect the core from moisture ingress, which is directly relevant to long-term condensation resistance in an RV wall.

We do not ship panels to a specification and leave you to work out the rest. We review your design, flag potential issues before production starts, and support you through integration. If you are specifying sandwich panels for an RV wall, floor, or ceiling application, contact our engineering team to discuss your panel configuration and get a specification that is matched to your build.