Navigating Fire Ratings and Compliance: What Designers Need to Know
Introduction
Fire safety is a fundamental consideration in the design and specification of building and infrastructure materials. For engineers and architects specifying Glass Reinforced Plastic (GRP), understanding its fire performance and regulatory compliance is essential. While GRP offers strength, corrosion resistance, and design flexibility, its suitability in a given application depends on selecting the correct fire performance grade and ensuring it aligns with both UK and international standards.
This article provides a clear overview of how GRP is tested, the meaning of its fire ratings, and how to apply this knowledge when specifying products for real-world projects.
Fire Performance Basics for GRP
In the UK, GRP fire performance is most commonly classified using BS 476 Part 7, which measures the surface spread of flame on building materials. Class 1 indicates the lowest spread of flame, with Class 2 also widely accepted in many infrastructure applications. Most structural GRP products from Engineered Composites are manufactured to achieve Class 2 under BS 476 Part 7, ensuring suitability for a wide range of environments, including public walkways, rail infrastructure, and utility platforms.
Fire performance can also be tested to ASTM E84 (the “Steiner Tunnel Test”) for international projects, which rates materials for both flame spread and smoke development. This ensures compatibility with projects that must meet global compliance requirements.
How GRP Achieves Fire Resistance
Fire-retardant GRP products are manufactured using resins formulated with halogen-free additives that slow ignition and reduce flame spread. In addition, the inclusion of a surface veil during pultrusion can help limit heat transfer and improve performance under fire conditions.
Unlike untreated timber, GRP will not continue to burn once the ignition source is removed. It also avoids the spalling issues that can occur with concrete under high heat. However, GRP is an organic composite and will char at high temperatures, so correct specification remains essential for safety.
Compliance in Different Applications
The appropriate fire rating for GRP varies depending on where and how it will be used:
- Public Access Structures — Pedestrian bridges, platforms, and handrails should meet Class 2 under BS 476 Part 7 to ensure flame spread is limited in the event of an incident.
- Rail and Transport — Network Rail-approved GRP components, such as GRP mesh fencing and handrails, must meet defined fire performance criteria to be used near public access points.
- Utility Infrastructure — In substations and chemical plants, fire retardancy is combined with electrical insulation, as in the Alyth Substation GRP palisade fencing.
- Marine and Offshore — Coastal environments require GRP with both fire performance and saltwater resistance for safety-critical installations.
Case Studies Demonstrating Compliance
The Poole’s Wharf pedestrian bridge refurbishment used Deck 500 anti-slip panels manufactured to Class 2 fire performance. This ensured that the upgraded bridge surface not only provided improved slip resistance but also met safety requirements for public access in a busy urban area.
Similarly, Copenhagen Kastrup Airport’s blast wall, built from GRP structural profiles, achieved Class 2 performance while withstanding the challenges of a coastal, high-security location.
Integration with Standards and Specification Documents
When specifying GRP, designers should include the required fire performance in the project documentation alongside mechanical and environmental requirements. This allows suppliers to select the correct resin systems and ensure that test certificates are provided with the material delivery.
Engineered Composites supplies full certification packages confirming compliance with BS 476 Part 7 Class 2 or other applicable standards, along with supporting data for mechanical performance and environmental durability.
Conclusion
GRP can meet stringent fire performance standards when correctly specified. By understanding the meaning of Class 2 fire ratings, how GRP achieves this performance, and where it applies, designers can confidently integrate GRP into safety-critical projects.
With accurate certification and alignment to recognised standards, GRP becomes not only a structurally capable and durable choice, but also a compliant and safe material for use in environments where fire performance is non-negotiable.
For more on specifying GRP to meet both structural and safety criteria, explore the full range of Engineered Composites products.
