FRP grating is one of those industrial products where the purchase price tells you almost nothing about what it actually costs to own. A square meter of standard molded FRP grating costs $80-150, versus $40-60 for galvanized steel bar grating of the same load rating. Procurement departments see a 2-3× price premium and reject the FRP quote without making a second phone call. Then the galvanized steel grating is installed in a chemical plant, the zinc coating is scuffed off within six months of foot traffic and chemical drips, the bare steel underneath corrodes through in three to five years, and the entire platform has to be replaced—with the plant shut down for two weeks during the replacement. The FRP grating that was rejected at $120/m² would have lasted twenty years with zero corrosion-related maintenance, at a total cost of ownership roughly one-third of the galvanized steel alternative. This article breaks down what FRP grating actually costs, what drives the price differences between molded and pultruded products, and how to calculate the lifecycle cost of your specific application rather than just comparing per-square-meter purchase prices.
| Property | Molded FRP Grating | Pultruded FRP Grating | Galvanized Steel (Reference) |
|---|---|---|---|
| Cost per m² | $80-150 | $120-200 | $40-60 |
| Span at 38mm thickness (UDL 500kg/m²) | 1.0m | 1.2-1.5m | 1.5m+ |
| 20-year TCO (100m² chemical plant) | ~$50,000 | ~$65,000 | ~$76,000 |
| Replacement cycle (moderate chemical exposure) | 20+ years | 20+ years | 5-10 years |
| Corrosion maintenance | None | None | Annual inspection + spot painting |
Molded vs Pultruded Grating: The Cost-Performance Tradeoff
Molded FRP grating is made by laying continuous glass fiber rovings and chopped strand mat into a steel mold in an orthogonal grid pattern, saturating with polyester or vinyl ester resin, then curing under heat and pressure. The result is a one-piece grid with square or rectangular openings, typically in panel sizes of 1.0×3.0m or 1.2×2.4m. Molded grating has equal strength in both directions (it’s isotropic in the plane), which means it can be cut and installed without worrying about orientation. Standard cost range for 25-38mm thick molded FRP grating with polyester resin: $80-150/m² at the factory gate, FOB. Pultruded FRP grating is made by assembling pultruded bearing bars (T-shaped or I-shaped profiles) with cross-rods through pre-drilled holes, then bonding the assembly with resin. The bearing bars provide strength in the span direction, while the cross-rods hold the assembly together and transfer load between bars. Cost range: $120-200/m². Pultruded grating is more expensive per square meter than molded. But—and this is the critical distinction—pultruded grating can span longer distances for the same thickness. A 38mm molded grating panel on 1.0m support centers carries roughly 500-700 kg/m² uniformly distributed load. A 38mm pultruded grating panel with T-bars on the same support spacing carries 800-1,200 kg/m². If you’re replacing steel grating on 1.2m or 1.5m support centers—which is common in industrial platforms designed for steel—the molded grating may not meet the span requirement at any practical thickness, while the pultruded grating handles it at 38mm. In that scenario, the “more expensive” pultruded grating is actually the cheaper solution, because it eliminates the cost of adding intermediate supports. The decision between molded and pultruded FRP grating is not a price decision. It’s a span-and-load decision. Compare the manufacturer’s load tables at your actual support spacing before comparing prices.
Resin Type: The Hidden Cost Multiplier
The resin system changes the grating price by 30-60% and determines where the grating can be used. Standard isophthalic polyester resin (ISO) is the baseline—good for general industrial use with occasional chemical splashes, outdoor weathering with UV-stabilized formulation, and operating temperatures up to 80°C. Most molded grating sold globally uses ISO polyester. Vinyl ester resin (VE) adds 30-50% to the material cost and provides superior chemical resistance—specifically to strong acids (hydrochloric, sulfuric up to 70%), strong alkalis (sodium hydroxide up to 50%), and oxidizing agents (wet chlorine, bleach). Vinyl ester grating is spec’d for chemical processing areas, electroplating shops, bleach plants, and wastewater treatment facilities with high chlorine dosing. The cost premium for VE is typically $30-60/m² over the ISO equivalent. Phenolic resin adds 50-60% to the cost and provides the best fire performance—low smoke, low toxicity, and low flame spread (ASTM E84 Class 1). Phenolic grating is specified for occupied spaces with fire safety requirements: offshore platform accommodations, railway tunnels, subway stations, enclosed walkways. If your application doesn’t need the fire performance of phenolic or the chemical resistance of vinyl ester, don’t pay for them—isophthalic polyester is the cost-optimized choice for the majority of industrial FRP grating applications. But if you’re grating a chlorine storage area, the extra $40/m² for vinyl ester resin is cheaper than replacing the grating in two years because the polyester resin was attacked by chlorine.
Lifecycle Cost: The Calculation That Changes Everything
The formula for comparing FRP and galvanized steel grating over time is straightforward but rarely calculated before procurement: TCO = Purchase_Price + Installation_Labor + (Annual_Maintenance_Cost × Years) + (Replacement_Cost × Number_of_Replacements) + (Downtime_Cost × Number_of_Replacements). For a 100m² platform in a chemical plant with occasional acid splashes, the twenty-year numbers look roughly like this. Galvanized steel: purchase $5,000 (at $50/m²), installation $3,000 (welding and touch-up painting), annual maintenance $500 (inspection, spot painting of rust), replacement at year 7 and year 14: $5,000 each for material + $4,000 each for labor + $20,000 each for two weeks of plant downtime to replace the grating. Total TCO: $5,000 + $3,000 + ($500 × 20) + ($29,000 × 2) = $76,000. Molded FRP with ISO polyester: purchase $12,000 (at $120/m²), installation $2,000 (cutting with diamond blade, no welding, no painting), annual maintenance $0 (periodic washdown only), replacement at year 20: $12,000 material + $4,000 labor + $20,000 downtime. Total TCO: $12,000 + $2,000 + ($0 × 20) + ($36,000 × 1) = $50,000. The FRP option saves $26,000 over twenty years—more than double the initial purchase price difference—driven entirely by eliminating one replacement cycle. If the plant operates continuously and the downtime cost is higher than $20,000 per replacement, the FRP advantage gets larger. If the grating is in an area that can be replaced without shutting down the entire plant, the advantage narrows but doesn’t disappear. This is a simplified calculation—real applications have their own specific numbers—but the structure of the comparison holds across almost every corrosive industrial environment. The FRP grating costs more to buy and less to own. The question procurement departments should be asking is not “what’s the price per square meter?” but “what’s the twenty-year cost?”
