GRP Grating Load & Span — Working Load Tables
How to Read GRP Grating Load & Span Tables
Every working load below is transcribed from manufacturer molded and pultruded load catalogs at static, ambient-temperature conditions. Use the Max Recommended figure — it already includes the safety factor. Set bearers to the rated span; never bridge beyond it.
Safety Factor
Molded: 5:1 on ultimate capacity. Pultruded: 2:1. HLC vehicle wheel loads: 2.5 based on 0.25" max deflection.
Deflection Limit
Pedestrian walkway: lesser of L/120 or 3/8". Pultruded comfort: lesser of 3/8" or L/125; firm: lesser of 1/4" or L/200.
Live Load Basis
Walking uniform live load typically 50–65 psf; concentrated load 250 lb. For impact or dynamic loading, use 1/2 of the tabulated values.
Molded GRP Grating — Recommended Max Load (kg/m²)
Clear span in metres, ZeAllgrate molded metric range. Thicker panel and narrower span carry more uniform load.
| Thickness × Mesh | 0.30 m | 0.61 m | 0.91 m | 1.22 m |
|---|---|---|---|---|
| 25.4 mm · 38.1 sq | 8788.4 | 2001.8 | 878.8 | — |
| 38.1 mm · 38.1 sq | 18162.6 | 5810.1 | 2392.4 | 1074.1 |
| 38.1 mm · Mini-Mesh | 18162.6 | 5810.1 | 2392.4 | 1074.1 |
| 50.8 mm · 50.8 sq | 20896.8 | 7079.5 | 2929.5 | 1660.0 |
Recommended max uniform load, kg/m². Source: ZeAllgrate Molded Fiberglass Grating Metric Brochure.
Pultruded GRP Grating — Max Recommended / Ultimate (psf)
Pultruded I-bar and T-bar profiles span much further than molded panels. Values shown per clear span in inches; orient bearing bars across the span.
| Profile | 24 in | 36 in | 48 in | 60 in | 72 in |
|---|---|---|---|---|---|
| I4010 (1" I-bar) | 2540 / 5080 | 1760 / 3520 | 1080 / 2160 | 690 / 1380 | — |
| I4015 (1-1/2" I-bar) | 4790 / 9580 | 3690 / 7380 | 2110 / 4220 | 1350 / 2700 | 940 / 1880 |
| T3320 (2" T-bar) | 3960 / 7920 | 2880 / 5760 | 2160 / 4320 | 1360 / 2720 | 950 / 1900 |
Walking loads typically 50–65 psf; static ambient only, impact = 1/2 values. Source: ZeAll Pultruded load tables p.6.
Molded vs Pultruded — Which Fits Your Span
HR = highly recommended, R = recommended, A = acceptable, NR = not recommended.
| Criterion | Molded | Pultruded | Note |
|---|---|---|---|
| Corrosion resistance | HR | HR / R | All systems rated HR/R |
| Bi-directional span | HR | NR | Molded square mesh carries load both ways |
| Single-direction long span | A | R | Pultruded bearing bars along the span |
| Ease of installation | A | HR | Pultruded panels cut and clip faster |
| Custom panel sizes | R | NR | Molded molds to near-custom dimensions |
Load & Span Engineering PDFs
Take the full load charts and resin temperature guide to your desk. Final design is confirmed against certified charts for your exact panel.
Frequently Asked Questions
Molded GRP grating has bi-directional strength from its square mesh and carries load in both panel directions. Pultruded GRP grating is unidirectional: its I-bar, T-bar and square bearing bars span long distances, so bars must be oriented across the support spacing.
For pedestrian walkways we limit deflection to the lesser of L/120 or 3/8 inch. Pultruded comfort design uses the lesser of 3/8 inch or L/125, and firmer flooring the lesser of 1/4 inch or L/200. HLC vehicle loads use 0.25 inch maximum deflection.
Molded grating uses a 5:1 factor of safety on ultimate capacity; pultruded grating uses 2:1; HLC vehicle wheel loads use 2.5 based on 0.25 inch deflection. Tables show Max Recommended / Ultimate values so the working load already includes the factor.
For long unsupported spans, pultruded I-bar and T-bar grating is the right choice. Our I4015 and T3320 profiles carry uniform loads out to 60–72 inch clear spans. Use molded grating where load acts in both directions or where custom panel dimensions matter.
Yes, with high-load-capacity (HLC) molded grating. Our 1-1/2 inch and 2 inch HLC styles are rated for automobile, 1-ton to 5-ton forklift and AASHTO H-20 truck wheel loads, with parallel and perpendicular spans tabulated. Apply 1/2 the tabulated value for impact or dynamic loading.
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