Fiberglass Gratings (FRP) & Structural Deck Panels

Choose molded grating when loads arrive from both directions, the layout needs many field cutouts, or maximum chemical resistance is the priority: its woven, resin-rich construction (30-35% glass by weight) gives near-equal two-way strength and the best corrosion performance. Choose pultruded grating when the design is span-driven: its unidirectional bearing bars (60-65% glass) carry significantly longer clear spans with fewer supports, and dedicated series cover ADA pedestrian surfaces, 73-83% open cooling-tower decks, and forklift-rated high-load platforms. Both families are produced to ASTM E84 Class 1 flame spread (FSI ≤25).

The dedicated pedestrian series are. ADA/ABA surface rules require walking-surface openings of 13 mm (1/2 in) or less in the dominant direction of travel; our T-2510 and T-2515 pedestrian T-bar gratings (12.7 mm slot at 50.8 mm bar centers) and the I-4010 industrial I-bar (≈10 mm slot at 25.4 mm centers) meet that limit and are marked ADA in the specification table on this page. Open-mesh industrial and cooling-tower series (38-83% open area) prioritize drainage and airflow instead and are not intended for ADA-governed pedestrian routes — specify by series, not by material family.

FRP gratings are open-mesh panels formed by bi-directional glass fiber (molded) or by interlocking pultruded bearing bars (pultruded). They provide high drainage, light transmission, and reduced wind load, but small objects can fall through the mesh. FRP deck panels (also called structural deck planks) are closed-top pultruded planks with internal webs and an integrally sealed top surface — they carry concentrated loads without requiring a cover plate, span longer than gratings of equivalent depth, and are the preferred specification for pedestrian bridge decks, vehicular access platforms, and FRP bridge deck replacement projects.

In North American construction specifications, fiberglass reinforced gratings are specified under CSI MasterFormat Section 06 74 13 (Fiberglass Reinforced Gratings), within Division 06 — distinct from metal gratings, which sit in Division 05 (05 53 00). Specifying under 06 74 13 keeps the corrosion-resistance, load-deflection, and fire-rating requirements in a section written for composites rather than forcing FRP into a steel-grating spec. F1 supports 06 74 13 submittals with load tables, ASTM E84 flame-spread data, and batch material test reports.

F1 Composite pultruded FRP deck panels span up to 3.6 m under pedestrian load with a 100 mm panel depth. Shorter spans of 1.2–2.4 m are typical for panels rated to AASHTO H-10 or H-20 vehicular load. For longer pedestrian bridge decks, multiple panels are spliced with tongue-and-groove joints and supported on intermediate FRP or steel cross-beams. Full span/load/deflection tables are available on request for project-specific design.

FRP gratings weigh approximately 25-35% of an equivalent steel grating, which dramatically reduces structural support requirements, transport costs, and installation labor. A standard 38 mm molded FRP grating weighs approximately 19.5 kg/m² compared to 55-65 kg/m² for a comparable hot-dip galvanized steel grating. In terms of load capacity, FRP gratings are designed to the same load class specifications as steel, though the lower elastic modulus of FRP means that deflection often governs the design, particularly at longer spans.

FRP gratings are the preferred specification for offshore platforms, vessels, and coastal infrastructure precisely because they are immune to the corrosion mechanisms that destroy steel gratings in marine environments: salt spray, immersion, wet-dry cycling, and galvanic corrosion from contact with dissimilar metals. Vinyl ester resin gratings provide the highest resistance to hydrolysis and chemical attack in marine applications. We supply gratings to major offshore operators and shipyards worldwide, with product certifications from DNV, Lloyd’s, and ABS.

Yes. Both molded and pultruded FRP gratings can be cut on site using standard carbide-tipped circular saws or reciprocating saws. Molded gratings are particularly easy to cut to irregular shapes because the bi-directional fiber architecture maintains structural integrity regardless of the cut direction. Pultruded gratings should ideally be cut so that bearing bars span the load direction, and we recommend that significant cut-outs be planned during the panel layout stage rather than executed in the field. Dust extraction and particulate respiratory protection are recommended during cutting.

Our standard isophthalic polyester gratings achieve ASTM E84 Class 1 fire rating with a flame spread index of 25 or less. For applications requiring enhanced fire performance such as offshore platforms, tunnels, and transit infrastructure, we offer gratings in fire-retardant resin formulations that achieve flame spread indices below 10 and generate significantly lower smoke density and toxic gas emission. We can provide gratings tested to IMO Resolution MSC.307(88) for marine applications and EN 13501-1 Euroclass ratings for European building projects.