How to Specify GRP in Any Project — A Step-by-Step Guide
Introduction
Switching to Glass Reinforced Plastic (GRP) can deliver benefits in durability, safety, and sustainability, but many engineers and specifiers hesitate because they are less familiar with its standards, design parameters, and installation requirements. In reality, specifying GRP follows a logical process similar to traditional materials, with a few key considerations that ensure it meets both performance and compliance needs.
Step 1 — Define the Application and Environment
As with any material, the first stage is understanding where and how the GRP will be used. Factors such as exposure to weather, contact with chemicals, load requirements, and proximity to live electrical systems influence the choice of resin, profile type, and surface finish. For example, coastal or chemical environments may require vinyl ester resins for enhanced resistance, while internal applications may be suitable for polyester resins.
Step 2 — Confirm Standards and Compliance
One of the most common concerns about specifying GRP is whether it meets the same recognised standards as steel or aluminium. GRP structural profiles should comply with BS EN 13706, which defines grades and performance requirements for pultruded profiles. For gratings and flooring, BS EN 4592 provides guidance on loading capacities and slip resistance. Fire performance can be specified to Class 2 under BS 476 Part 7 for applications where flame spread must be controlled.
Step 3 — Determine Structural Requirements
Understanding the mechanical properties is essential to ensure the GRP section can handle the anticipated loads. Tensile strength, modulus of elasticity, and shear strength values should be reviewed in manufacturer datasheets. Because GRP is lighter than steel, some engineers mistakenly assume it is weaker; however, with tensile strengths in the range of 483 to 1600 MPa, it is more than capable of meeting the demands of most industrial walkways, platforms, and safety systems.
Step 4 — Select Profiles and Components
GRP profiles are available in standard shapes and sizes that align with conventional steel sections, including box sections, channels, and I-beams. This allows for direct substitution in many designs without major changes to the structural layout. Ancillary components such as fixings, handrail systems, and anti-slip surfaces should be chosen to match the application’s safety and durability requirements.
Step 5 — Consider Fabrication and Installation
Another hesitation around GRP is whether it requires specialist tools or skills to install. In fact, GRP can be cut, drilled, and fabricated with standard hand and power tools, and its lighter weight allows manual handling in many cases. Prefabrication can further reduce installation time and minimise disruption on site.
Step 6 — Plan for Maintenance and Lifecycle
While GRP requires minimal maintenance, it is important to build in an inspection regime to check for surface wear, impact damage, or fastener integrity. Maintenance plans should note that GRP does not require repainting or corrosion treatment, which can reduce lifecycle costs by 30 to 50 percent compared to steel.
Step 7 — Document the Specification Clearly
Including the correct product codes, standards, mechanical properties, and installation requirements in the specification ensures contractors can source the right components and avoid substitutions with lower-grade materials. Many suppliers can provide standard specification clauses for integration into project documentation.
Conclusion
Specifying GRP is straightforward when approached methodically. By defining the application, confirming compliance with recognised standards, selecting the correct profiles, and planning for installation and maintenance, GRP can be integrated into almost any project with confidence. For engineers and specifiers looking to deliver durable, safe, and sustainable infrastructure, it is a material that meets both performance demands and modern environmental expectations.
