GRP is not fireproof, but it is not highly combustible either. The material can be made fire resistant by using special resins and additives. Research published in Polymers (PubMed Central) confirms that brominated vinyl ester epoxy resins combined with alumina trihydrate mineral fillers can significantly lower flue gas temperature and reduce flame spread compared to standard resin systems. This improves reaction to fire and boosts overall fire safety. Fire performance is crucial when selecting materials for projects where safety matters most.

GRP and Fire: The Basics

Is GRP Fire Resistant or Flammable?

Glass Reinforced Plastic (GRP) is neither fireproof nor highly combustible. Its fire resistant properties depend on the resin type and additives used during manufacture. Some GRP products can resist flames and slow the reaction to fire, while others may ignite more readily if made with standard resins.

Fire classification systems measure ignition, flame spread, and smoke production. Requirements for fire resistance often vary by building location — escape routes and service shafts typically demand materials with the highest fire resistance. Factors determining whether GRP is fire resistant or flammable include resin grade, additives, fire classification standards, and building safety requirements.

How GRP Behaves in Fire

When GRP is exposed to open flame or high heat, its behavior depends heavily on the materials used in construction. Fire resistant GRP often contains additives that promote self-extinguishing behavior — they create a protective char layer when heated, which slows flame spread and limits further degradation.

Materials with a Limiting Oxygen Index above 21 are considered self-extinguishing, meaning they require more oxygen than is present in normal air to sustain combustion. GRP formulated with the right additives can achieve this threshold. Key fire behaviors include:

• Forms a char layer that suffocates flames and limits mass transfer

• Suppresses smoke generation from the underlying material

• Does not melt or drip — remains structurally intact during a fire event

Fire Resistance Ratings for GRP

Common Fire Standards

Fire resistance ratings show how materials perform under heat, flame, and smoke exposure. GRP fire performance depends on its classification and resin grade. The most widely used standards are ASTM (United States) and EN (Europe). These measure ignition, flame spread, and overall fire resistance.

For full test methodology details, the Intertek ASTM E108 standard overview provides authoritative guidance on test procedures and classification criteria.

EN standards such as EN 13501 classify materials based on reaction to fire and smoke production, and are commonly referenced for GRP walkways, platforms, and industrial structures across European markets.

What Fire Ratings Mean in Practice

Fire ratings guide engineers and builders on the suitability of GRP for critical applications. A Class 1 rating to BS 476 Part 7 indicates very limited flame spread, making the material appropriate for walkways, stairs, and platforms in industrial and commercial buildings. For more on BS 476 compliance in practice, the BS476 GRP grating fire resistance guide offers a clear technical explanation.

What Affects GRP Fire Performance

Resin Types and Additives

The fire performance of GRP depends primarily on resin type and additive selection. Standard resins provide basic structural properties but limited fire resistance. Fire-retardant grades use brominated compounds or mineral fillers such as alumina trihydrate to inhibit ignition and slow combustion.

GRP Thickness and Structure

Thicker GRP profiles take longer to heat through and provide greater structural integrity during a fire. Layered or reinforced constructions also improve fire performance. GRP profiles from NHC are engineered with fire performance in mind, meeting classification requirements for demanding industrial applications.

Smoke and Fume Production in Fire

Does GRP Release Toxic Fumes?

When GRP burns, the type and volume of fumes depend on the resin system and additives used. Most GRP uses thermosetting resins, which generally produce less smoke than many commodity plastics. Fire resistant GRP grades are formulated to minimize toxic fume release. The primary gases of concern during combustion are carbon monoxide and carbon dioxide, with only trace amounts of other compounds when fire-retardant formulations are used.

Smoke Compared to Other Materials

GRP produces lower smoke density than most thermoplastics and does not melt or drip, which limits the spread of burning material. This makes it a more predictable and manageable material in fire scenarios compared to PVC or polystyrene.

Where Fire Resistant GRP Is Required

Applications and Regulatory Standards

Fire resistant GRP is widely specified across industrial, civil, and offshore sectors. Building codes and safety regulations frequently mandate fire-rated materials in the following areas:

When Standard GRP Is Acceptable

Standard GRP is suitable for lower-risk outdoor applications such as garden fencing, signage, and non-load-bearing architectural elements where flame spread risk is minimal. Consult with your supplier to confirm compliance for your specific project.

Specifying the Right GRP Fire Grade

Fire Grade Properties Comparison

Selecting the correct fire grade requires matching the material's tested performance to your project's safety classification. The table below — drawn from published technical data — compares key fire properties across GRP resin types. For full technical data, see the GRP technical data reference.

Key Questions for GRP Suppliers

• What is the UL 94 flammability classification (V-0, V-1, or V-2) for this product?

• What is the full composition of the GRP, including any flame-retardant additives?

• Can you provide third-party laboratory test reports from accredited agencies such as UL, VDE, or TUV?

• Does the product comply with BS EN 13501 and BS 476 Part 7 for your intended application?

• Does testing cover the finished profile, not just raw resin components?

GRP vs. Other Materials in Fire

GRP vs. Steel

GRP offers advantages over steel in corrosive environments and where weight savings are important — and fire-rated grades perform reliably in demanding fire scenarios.

GRP Grating vs. Alternatives

Fire-rated GRP grating achieves a Class 1 fire rating under BS 476 Part 7, meaning very limited flame spread. Compared to alternatives:

• GRP grating: self-extinguishing, does not melt or drip, low smoke output

• Aluminum grating: does not burn but loses structural strength at high temperature

• PVC grating: can melt, drip, and produce dense toxic smoke

For environments requiring both fire resistance and corrosion protection, GRP grating represents a strong and compliant solution. GRP wall panels made from fire-retardant resins similarly resist flame spread, avoid toxic fume emission, and add structural durability — making them a reliable choice for building interiors and industrial enclosures.

GRP is not fireproof, but it can deliver strong, reliable fire resistance when specified with the correct resin system and validated against recognized fire standards. Always confirm fire ratings with your supplier and request certified test data for the finished product.

Frequently Asked Questions