Comparison
FRP vs Steel vs Aluminum Grating
The honest version: steel wins on first cost and fire, aluminum wins on weight per dollar, FRP wins everywhere your deck gets wet, chemical or salty. Here are the numbers.
| Property | FRP (vinyl ester) | Hot-dip galvanized steel | Aluminum |
|---|---|---|---|
| Corrosion in chemical / salt service | Immune — barrier is full thickness | Coating fails in 3–5 yrs, then rusts fast | Pits in chloride environments |
| Weight at comparable duty | ~19 kg/m² | ~30–35 kg/m² (open bar) | ~12 kg/m² |
| Stiffness (deflection at 1 m, same load) | Moderate | Highest | Moderate |
| Electrical conductivity | None — non-conductive | Conductive | Conductive |
| Spark from dropped tools | None | Yes | Yes |
| Magnetic | No | Yes | No |
| Fire performance | Class 1 (VE / phenolic) | Non-combustible (loses strength hot) | Non-combustible (softens ~200 °C) |
| Cutting on site | Hand tools, no edge sealing (molded) | Welding / grinding, touch-up galvanizing | Cuts easily, edges sharp |
| Maintenance cycle | None | Inspection + recoat / replace | Inspection; cleaning in marine air |
20-year installed cost, 100 m² corrosive-area walkway (indicative model)
| Cost item | FRP (VE) | Galvanized steel | Aluminum |
|---|---|---|---|
| Material + install (year 0) | 1.30 × steel base | 1.00 (base) | 1.10 |
| Recoat / touch-up cycles (yrs 5, 10, 15) | 0 | 0.45 | 0.15 |
| Partial replacement (yrs 8–12) | 0 | 0.80 | 0.10 |
| Access / shutdown premium per maintenance event | 0 | 0.35 | 0.15 |
| 20-year total | 1.30 | 2.60 | 1.50 |
Model assumes corrosive service (chemical splash, wastewater H₂S or marine salt). In a dry, non-corrosive interior, galvanized steel remains the rational first choice — we will tell you so. Multipliers are indicative; send your walkway area and environment for a project-specific comparison.
The one-line version for your approval memo
FRP costs about 30% more on day one and roughly half as much over twenty years in corrosive service — and it eliminates the repaint shutdowns that drive the difference.