There is no single safe span for GRP grating. Allowable support centres depend on the exact panel, depth, construction, resin, load type, load magnitude and deflection criterion. A span table is meaningful only when every one of those inputs matches the proposed installation.
In brief
- Panel depth alone does not determine span.
- Uniformly distributed loads and concentrated loads must be checked separately.
- Serviceability deflection may govern before ultimate strength.
- Openings, cut edges, narrow strips and removable panels can require extra support.
The six inputs that control span
| Input | Why it matters |
|---|---|
| Product form | Moulded and pultruded grating carry load differently |
| Panel depth and geometry | Changes stiffness and capacity |
| Load case | UDL, point, line and wheel loads produce different effects |
| Deflection limit | Controls movement, comfort and serviceability |
| Bearing direction | Pultruded load bars and some panel geometries have a defined span direction |
| Support detail | Bearing width, continuity, fixings and edge framing affect behaviour |
A reliable checking sequence
- Identify the exact product code, depth, resin and surface.
- Measure the clear span and record the bearing direction.
- Define every credible load, including local maintenance and wheel loads.
- Read the manufacturer’s table for that product and load case.
- Check both ultimate capacity and the project deflection limit.
- Add support around openings, joints, cut edges and narrow remnants.
- Have unusual or safety-critical layouts reviewed by a competent designer.
Why copying one number is risky
A figure quoted for a 38 mm moulded panel under a uniform load cannot safely be transferred to a pultruded panel, point load or wheel load. Even panels with the same nominal depth may use different mesh geometry, reinforcement and test assumptions. Use the Technical Hub to reach the relevant data and record the revision used.
Frequently asked questions
Does thicker GRP grating always span farther?
Often it is stiffer, but thickness is only one variable. Product construction, bearing direction, load and deflection criteria still need checking.
Should I use the clear opening or support-centre distance?
Follow the definition used in the manufacturer’s table or calculation. Do not mix clear span and centre-to-centre dimensions.
Can clips increase the allowable span?
Hold-down clips restrain the panel but normally do not replace structural support or increase the verified span.
Check the exact span before ordering
Send the panel type, clear opening, support layout and load case to GRP Express, or start with our GRP grating range.