Material Performance Requirements for GRP Riser Grating
GRP riser grating panels installed within service void flooring systems must meet defined mechanical performance standards to ensure safe load support, structural stability and long-term durability.
Material properties are specified in accordance with BS EN 13706, which defines minimum tensile strength, flexural strength and stiffness requirements for structural glass reinforced polymer (GRP) composites.
For multi-storey service riser installations, correct material grade selection plays a critical role in panel rigidity, allowable span performance and long-term structural reliability.
Minimum Mechanical Properties Under BS EN 13706
The table below outlines the minimum mechanical properties required under BS EN 13706 for E17 and E23 grades. These values establish the baseline structural performance for GRP riser grating panels used within service void flooring systems.
| Units | Property Data | ||
| E23 Grade | E17 Grade | ||
| Full section modulus | GPa | 23 | 17 |
| Tensile strength (axial) | MPa | 240 | 170 |
| Tensile strength (transverse) | MPa | 50 | 30 |
| Tensile Modulus (axial) | GPa | 23 | 17 |
| Tensile Modulus (transverse) | GPa | 7 | 5 |
| Flexural strength (axial) | MPa | 240 | 170 |
| Flexural strength (transverse) | MPa | 100 | 70 |
| Inter-laminar shear | MPa | 25 | 15 |
| Pin bearing strength | MPa | 70 | 50 |
How Mechanical Properties Influence Riser Flooring Performance
The mechanical properties defined under BS EN 13706 directly influence how GRP riser grating panels perform in service void environments.
In multi-storey riser installations, structural behaviour under load is determined not only by panel thickness, but also by the material grade used in manufacture.
Tensile Strength
Axial tensile strength affects how the panel resists structural stresses when spanning between support angles within the riser opening. Higher tensile performance contributes to improved structural reliability under maintenance loading.
Flexural Strength
Flexural strength determines how the panel behaves under distributed loads. In service risers, this is critical where maintenance personnel, tools or service equipment may apply temporary load to the flooring system.
Modulus of Elasticity (Stiffness)
The modulus of elasticity influences panel rigidity and deflection performance. Higher modulus values reduce perceived movement underfoot and improve overall span capability.
Inter-Laminar Shear & Bearing Strength
These properties influence fixing performance and load transfer at support points. In riser flooring systems secured with mechanical fixing clips, material integrity at connection points is essential for long-term stability.
Material Grade and Panel Thickness in Service Riser Applications
Material grade and panel thickness are separate but closely related factors in the structural performance of GRP riser grating systems.
Material grade defines the minimum mechanical strength and stiffness of the composite. Panel thickness determines structural depth, which influences span capability and deflection behaviour within the riser opening.
In service riser installations, both must be considered together.
Thinner panels installed over closer support centres may perform adequately when manufactured to the appropriate material grade. As panel thickness increases, structural depth improves, allowing greater span distances and enhanced rigidity.
Higher performance grades such as E23 are typically specified for thicker structural sections to ensure improved load resistance and long-term stability in multi-storey riser environments.
Correct specification should consider:
- Span between supports
- Access and maintenance loading
- Fixing configuration
- Overall riser layout
For full dimensional data, panel weights and standard sizes, refer to our GRP Panel Sizes & Thickness specification page.
Frequently Asked Questions About GRP Structures & Fabrication
BS EN 13706 is a European standard that defines the minimum mechanical performance requirements for structural glass reinforced polymer (GRP) composites. In GRP riser grating applications, it establishes baseline tensile strength, flexural strength and stiffness values to ensure safe structural performance within service riser voids.
E17 and E23 are material grades defined under BS EN 13706. E23 grade provides higher tensile and flexural strength compared to E17, offering improved rigidity and load resistance. For thicker GRP riser grating panels and multi-storey installations, E23 is typically specified to ensure enhanced structural performance.
Yes. Material grade influences tensile and flexural strength, which directly affect how a panel performs between support angles. Higher performance grades can improve structural reliability and reduce deflection under maintenance loading within service riser voids.
Panel thickness and material grade work together. Thickness increases structural depth and stiffness, while material grade defines the inherent mechanical strength of the composite. Correct specification requires consideration of both factors to achieve safe riser flooring performance.
Structural sections with wall thickness greater than approximately 5mm are typically produced to E23 grade to provide enhanced tensile and flexural performance. This is particularly relevant for thicker riser grating panels used in larger service void openings.
Inter-laminar shear and bearing strength affect how loads transfer at fixing points where clips secure the panel to support frames. Adequate material performance ensures reliable long-term stability within service riser flooring systems.
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