Sandwich panels carry fire ratings that vary by core material, skin composition, and the specific test standard applied. In Europe, the relevant classification system is EN 13501-1, which assigns panels to lettered performance classes based on flame spread, heat release, and smoke production. Thermoplastic composite panels typically achieve ratings in the B to D range for wall and ceiling applications, and Bfl ratings for flooring products. The sections below work through how testing works, what the classifications mean, and what you need to verify before specifying a panel for a regulated application.
How are sandwich panels tested for fire performance?
Sandwich panels are tested for fire performance using a series of standardised European test methods that measure different aspects of combustion behaviour. The two most commonly applied tests are EN ISO 11925-2, which assesses ignitability by exposing a small flame to the panel surface, and EN ISO 9239-1, which measures flame spread across a flooring material under radiant heat. Wall and ceiling products are typically assessed using EN 13823 (the SBI test), which measures heat release rate and smoke production under a larger, more realistic fire scenario.
Each test isolates a specific fire behaviour rather than simulating a full fire event. Ignitability tests tell you how easily a panel ignites from a small flame source. Heat release tests tell you how much energy the panel contributes to a growing fire. Smoke tests measure optical density and toxicity of combustion gases. A panel’s final classification under EN 13501-1 is based on the combined results of whichever tests apply to its intended use category — flooring, wall cladding, or ceiling.
For transport applications such as truck bodies and trailers, the test regime can differ from building product standards. Vehicle interior materials may be assessed under sector-specific regulations, though many European OEMs now require EN 13501-1 classifications as a baseline because they align with the broader regulatory environment their customers operate in.
What fire classification system applies to sandwich panels in Europe?
EN 13501-1 is the European fire classification standard that applies to sandwich panels used in construction and many transport applications. It assigns products to performance classes — A1, A2, B, C, D, E, and F — based on their reaction to fire. Class A1 is non-combustible; Class F means no performance has been determined. Flooring products use a parallel scale with an “fl” suffix: Afl through Ffl. A secondary smoke designation (s1, s2, s3) and a droplet designation (d0, d1, d2) are appended to indicate smoke production and flaming droplet behaviour.
The classification is not a single pass/fail result. It is a composite descriptor. A panel rated B-s1,d0, for example, performs well on flame spread, produces very low smoke, and does not produce flaming droplets. A panel rated Bfl-s1 achieves equivalent performance specifically as a flooring material. Understanding the suffix is as important as reading the letter class, particularly in regulated environments where smoke toxicity is a design constraint — enclosed vehicle cabins and covered loading areas being obvious examples.
It is worth noting that EN 13501-1 classifies reaction to fire, not fire resistance. Reaction to fire describes how a material behaves when exposed to fire. Fire resistance (covered by EN 13501-2) describes how long a structure maintains its load-bearing or separating function under fire conditions. For most sandwich panel procurement decisions in commercial vehicles and scaffolding, reaction to fire classification is the relevant metric.
What fire ratings do thermoplastic composite panels typically achieve?
Thermoplastic composite sandwich panels typically achieve fire ratings in the B to D range under EN 13501-1, depending on skin material, core type, and panel thickness. Panels with glass-fibre reinforced thermoplastic skins tend to perform better than unreinforced polymer skins because the glass content limits flame spread. Core material has a significant influence: denser cores with less void space generally produce lower heat release rates than open-cell or low-density alternatives.
From our own product testing, Compoform’s QuikDeck floor panels — glass-fibre thermoplastic skins over a 140 kg/m³ PP-honeycomb core — are classified Bfl-s1 per EN 13501-1:2018, tested under EN ISO 11925-2:2010 and EN ISO 9239-1:2010. This means the product is combustible but achieves limited flame spread and very low smoke production, making it suitable for regulated interior and transport flooring applications. This is a specific test result for a specific configuration; other panel builds will produce different classifications.
Wall panels with PET-film surfaces or PP-based skins will carry their own classifications, which may differ from flooring products tested under the same standard. Never assume that a fire rating for one panel configuration transfers to another, even within the same product family. Always request the test report for the specific build you intend to specify.
Which industries and applications require specific fire ratings?
Commercial vehicle construction, public transport, scaffolding, and building cladding are the sectors where fire ratings for sandwich panels are most actively enforced. The specific rating required depends on the application, the regulatory body, and in some cases the end customer’s own procurement standards. You can review fire-rated panel applications across industries to understand how these requirements vary by sector.
In commercial vehicles and trailers, fire performance requirements are driven by a combination of type approval regulations and fleet operator specifications. Enclosed cargo bodies and refrigerated trailers are increasingly subject to interior material requirements, particularly where the vehicle operates in urban logistics or carries temperature-sensitive goods in populated areas. EV truck and van procurement teams in 2026 are also raising fire performance questions more frequently, given that battery thermal events create a different ignition risk profile than diesel powertrains.
In scaffolding, the relevant standard is EN 12811, which governs working platform performance including load capacity. Fire performance is not the primary classification driver for scaffolding boards, but contractors working on occupied buildings or in fire-sensitive environments may specify panels with documented reaction-to-fire classifications as part of their site safety plan.
In building and façade applications, fire ratings are strictly regulated under the Construction Products Regulation (CPR). Panels used as external cladding or internal wall linings must carry a Declaration of Performance referencing EN 13501-1 classifications. The regulatory environment tightened significantly across Europe following high-profile cladding fires, and specifiers now routinely require B or better for occupied buildings.
Can sandwich panel fire ratings be improved through material selection?
Yes. Fire ratings can be improved by selecting skin materials with higher glass or mineral fibre content, using denser core materials that limit oxygen availability within the panel, or applying fire-retardant treatments to the skin surface. Each approach targets a different aspect of combustion behaviour, and the most effective strategy depends on which part of the EN 13501-1 classification you need to improve — flame spread, smoke production, or heat release.
Skin selection has the most direct effect on ignitability and flame spread. Glass-fibre reinforced thermoplastic skins outperform unreinforced polymer skins because the glass fibres do not combust and create a partial barrier that slows flame propagation across the surface. Increasing the number of fibre plies or using a higher-density laminate further reduces the rate at which the skin contributes fuel to a fire.
Core density affects heat release. A higher-density PP-honeycomb core contains less polymer per unit volume than a lower-density alternative, which reduces the total combustible mass available to a fire. This is one reason why the 140 kg/m³ PP-honeycomb used in our QuikDeck floor panels supports a Bfl-s1 classification — the core geometry and density limit the panel’s contribution to heat release under test conditions.
Fire-retardant additives can be incorporated into skin or core formulations during manufacturing. These additives interrupt the combustion chain reaction, typically improving smoke and flame spread performance. However, they add cost and can affect other mechanical properties, so their use should be evaluated against the full performance specification rather than treated as a default upgrade.
How do you verify a sandwich panel’s fire rating before specifying it?
You verify a sandwich panel’s fire rating by requesting the original test report and Declaration of Performance from the manufacturer, then confirming that the tested configuration matches the panel you intend to use. A classification printed on a datasheet is only valid for the exact build that was tested — the same skin material, the same core type and density, the same adhesive system, and the same thickness range covered by the test.
When reviewing a fire test report, check the following:
- The test standard referenced — confirm it is EN 13501-1 and that the sub-tests (EN ISO 11925-2, EN ISO 9239-1, EN 13823) are appropriate for your application category (flooring, wall, ceiling)
- The panel configuration tested — skin material, number of plies, core type, core density, and total thickness must match your specification
- The classification result — read the full descriptor including smoke (s1/s2/s3) and droplet (d0/d1/d2) designations, not just the letter class
- The test date and issuing body — classifications issued by accredited third-party laboratories carry more weight with specifiers and regulators than manufacturer self-declarations
- The scope of the Declaration of Performance — if the panel is used in a building application, the DoP must reference the Construction Products Regulation and be issued by the manufacturer
If the panel you need differs from the tested configuration — different thickness, different core density, or a modified skin — the existing classification does not automatically apply. In that case, either request a new test or ask the manufacturer whether the classification has been extended to cover the variant through a field of application assessment.
How Compoform Supports Fire-Rated Panel Specification
We manufacture thermoplastic sandwich panels with documented fire classifications for commercial vehicle and scaffolding applications. Our QuikDeck floor panels carry a Bfl-s1 classification per EN 13501-1:2018, verified through third-party testing under EN ISO 11925-2 and EN ISO 9239-1 — a result we can provide in full test report form, not just as a datasheet reference.
When you bring us a specification, we do not simply match a standard panel to your order. We review your application, confirm which fire classification your end customer or regulatory environment requires, and identify whether our tested configurations cover your build or whether a different panel construction is needed. Specifically, we can support you with:
- Full test documentation for the specific panel configuration you are specifying
- Guidance on which skin and core combinations are likely to meet your target classification
- Custom panel dimensions cut to your exact requirements — no off-the-shelf constraints
- Technical review of your assembly design to flag integration issues before production begins
For truck body builders and trailer manufacturers, fire performance is one part of a broader panel specification that also covers payload weight, floor load capacity, and service life. A 30 mm PP sandwich panel floor is self-supporting with no aluminium subframe required, which removes a production step and reduces dead weight — relevant both for payload capacity and, in electric trucks and vans, for battery range per charge. Every kilogram of structural dead weight reduces range per charge, and EV fleet buyers are making that calculation at the procurement stage in 2026.
If you are specifying panels for a regulated application and need to confirm fire classification before committing to a build, contact our engineering team for specification support. We will review your requirements, provide the relevant test documentation, and work through the specification with you before anything goes to production.