A GRP grating load table tells you how a defined panel performs over a stated clear span under a stated load. It is useful only when the product, support direction, load type and deflection limit in the table match the proposed installation.
In brief
- Match the table to the exact grating family, mesh, depth, resin and surface finish.
- Distinguish a uniformly distributed load from a concentrated or point load.
- Read the clear span between supports, not the overall panel length.
- Check serviceability deflection as well as ultimate capacity.
- Refer unusual openings, wheeled loads, impact, vibration or safety-critical duties for technical review.
The figures are not interchangeable between manufacturers or product families. A 38 mm moulded panel, for example, must not be checked against data for a pultruded panel or a different mesh.
Start with the exact product
Before reading any numbers, confirm the product description at the top of the table. Record the panel depth, mesh pattern, bearing-bar direction where applicable, resin system and surface. These characteristics affect stiffness, support behaviour and environmental suitability.
Use the GRP grating range to identify the relevant family, then compare the proposed duty with the corresponding manufacturer data. If the panel has been cut into a narrow strip, contains a large opening or has unsupported edges, the standard full-panel result may no longer describe the installation.
Understand the load cases
| Term | What it means | Typical check |
|---|---|---|
| Uniformly distributed load (UDL) | Load spread over an area of the panel | Pedestrian occupancy, stored items or general platform loading where distribution is justified |
| Concentrated load | Load applied over a smaller stated area | A person, foot, support or local item acting at a defined position |
| Line load | Load applied along a line | Partitions, kerbs or equipment rails where the test data covers this case |
| Wheeled or dynamic load | Moving, repeated or impact loading | Trolleys, pallet trucks or plant; normally requires a specific assessment |
Never convert one load case into another by assumption. A panel that carries a stated UDL may not be suitable for a concentrated wheel load of a lower total value because local bending and contact stresses are different.
Read span and support conditions correctly
Span is normally the clear distance between the inside faces of the supports. It is not automatically the panel length. Moulded square-mesh panels can offer bidirectional behaviour, but cut geometry and support layout still matter. Pultruded grating has a primary load-bearing direction that must cross the supports.
- Confirm minimum bearing width and continuous edge support.
- Keep cut edges and penetrations supported where the product guidance requires it.
- Do not assume clips replace structural support.
- Check that removable panels cannot rock, lift or migrate in service.
Capacity and deflection answer different questions
Ultimate or failure data indicates strength under the stated test. Serviceability data indicates how far the panel is expected to move at a working load. A panel can remain below its ultimate capacity yet deflect too much for comfort, drainage falls, connected finishes or project criteria.
Selection rule: the governing result is the first applicable limit reached, whether that is strength, deflection, local behaviour, fixing capacity or a project-specific criterion.
Apply only the safety factors and allowable-deflection rules stated by the designer, standard, client specification or verified manufacturer guidance. Do not invent a universal factor from an unrelated table.
A practical five-step check
- Identify the exact grating and intended environment.
- Define every load case, including maintenance and temporary loads.
- Measure the clear support span and verify panel direction.
- Read the table at the required load and compare the stated deflection.
- Escalate any condition outside the published table.
When a standard table is not enough
Seek a project-specific review for vehicle or wheeled traffic, heavy point loads, large penetrations, cantilevers, unusual fixings, vibration, fire-performance requirements, aggressive chemicals or duties where failure would have serious consequences. GRP Express supplies standard and cut-to-size materials; engineered systems or specialist verification may be referred to Vital GRP where appropriate.
Useful GRP Express routes
Compare the available GRP grating products, review the GRP grating load tables, read the GRP standards and specification guide, or send the project details to GRP Express.
GRP load-table FAQs
Can depth alone determine the allowable span?
No. Mesh, construction, resin, bearing direction, support conditions, load case and deflection limit also matter.
Can I use UDL data for a point load?
No. Use data for the actual load type or obtain a specific assessment.
Do clips increase panel capacity?
Clips restrain and connect panels; they do not replace the supports assumed by the load table.
Final recommendation
Treat a load table as evidence for one defined arrangement, not a blanket approval. Record the product, load, span, supports and acceptance limit together so the selection remains traceable.
Listen to GRP Unpacked
Hear this load-table guide explained in its dedicated GRP Unpacked episode, with a full accessible transcript.