FRP Grating vs Aluminum Grating: When Each Material Wins
Both are light, both resist atmospheric corrosion. The split is conductivity, temperature ceiling, and what happens at end of life.
The choice most engineers skip
Once a project has ruled out steel, the next decision is usually between aluminium and FRP, not between steel and composite. Both are light, both survive outdoor air, and both look like a clean upgrade from painted steel. They diverge on three things: whether the grating is allowed to be an insulator, how hot the service environment gets, and what the site does with the panel at the end of its life. This page puts the two side by side on those axes so the spec note can be written in one line rather than re-litigated at every site review.
Side-by-side comparison
| Dimension | FRP / GRP grating | Aluminium grating | When aluminium wins |
|---|---|---|---|
| Self-weight per m² | Composite laminate density roughly 1800–2000 kg/m³; panel depth 25, 30, 38, 40, 50, 65 mm. | Density near 2700 kg/m³, but modulus near 70 GPa lets shallower sections meet deflection. | When stiffness-per-kilogramme on a light frame matters more than absolute density. |
| Stiffness source | Glass fibres carry tension in resin; modulus is an order of magnitude below aluminium. Tuned by depth and mesh (19×19, 12×12, 25×100, 38×38, 50×50). | Extruded or cast alloy; modulus near 70 GPa, so shallow bearing bars meet small deflections on short spans. | On short spans with tight deflection limits, aluminium sections are efficient. |
| Corrosion & media | Isophthalic, vinyl ester, polyurethane and phenolic resins cover acids, alkalis and chloride without an oxide layer to damage. | Self-healing oxide survives atmosphere and freshwater; fails in alkaline concrete runoff, strong acid, and uncoated chloride splash. | Aluminium wins in clean, dry, atmospheric walkways; FRP wins in chemical and coastal duty. |
| Electrical insulation | Intrinsically non-conductive; used around substations, rail transit and live equipment. | Conductive; bonds naturally into earthing and static-control networks. | Aluminium wins where the grating must be earthed; FRP wins where isolation protects workers. |
| Fire & heat | Resin-dependent; polyester and vinyl ester tested to ASTM E-84; phenolic for low-smoke. Softens above resin Tg (below 200 C prolonged). | Non-combustible but loses strength well below melting near 660 C; conducts heat laterally into structure. | Aluminium wins in direct-flame zones; FRP wins in low-smoke interiors. |
| Thermal conduction | Low thermal conductivity; does not carry heat away from hot equipment. | High thermal conductivity; spreads and dumps heat into the structure. | Aluminium wins where heat must be shed; FRP wins where hot pipes must stay isolated. |
| Fatigue & impact | Tough under footfall and casters; bi-directional molded lattice distributes point loads. | Ductile; yields rather than shatters. Good for walkways that take tool drop and light forklift traffic. | Aluminium wins on repeated heavy impact; FRP wins on corrosive fatigue. |
| Installation & field work | Cut with carbide tools; fasten with M/C/L/Z clips in SS304, SS316 or HDG. No welding, no dissimilar-metal galvanic isolation concerns. | Cut and drill easily, but dissimilar contact with steel bolts in chloride service causes galvanic corrosion; isolation washers needed. | Aluminium wins on pure fabrication speed; FRP wins where galvanic pairs must be avoided. |
| End-of-life & lifecycle cost | Thermoset cannot be remelted; recycling routes are limited. Cost drivers are resin grade, depth and anti-slip surface. | Scrap value is well established and recycling infrastructure exists in most markets. | Aluminium wins on circularity procurement criteria; FRP wins on maintenance-free corrosion duty. |
Conductivity is the deal-breaker on half of jobs
Engineers often compare FRP and aluminium on weight and conductivity and forget that one is an insulator and one is a conductor. If the grating sits on a substation deck, a rail transit platform, or a refinery walkway where workers must not bridge two live parts, FRP is the only answer. If the grating sits on a roof edge, a marine pontoon or a structure that needs to bleed static to earth, aluminium bonds naturally and FRP would require a separate earth strap that defeats the point. When you do the side-by-side deflection math, pull both vendors' tables on the same clear span and the same design load — our published cells on /frp-grating-load-table/ cover the 300 to 1200 mm axis in uniform, point and line modes, and your aluminium supplier will have an equivalent sheet. Compare the printed deflection, not the catalogue marketing copy.
Decision summary
Choose FRP grating when: the atmosphere carries acid, alkali or chloride; workers need electrical isolation from live equipment; hot pipes must not shed heat into the walkway; or dissimilar-metal galvanic pairs with steel supports are a concern. Browse molded 38×38, 19×19 mini, 25×100 and 50×50, and the pultruded range at 25×100, 38×38 and heavy I-bar.
Choose aluminium grating when: the grating must be part of the equipotential bonding network for static or lightning; the structure must shed heat laterally; end-of-life recycling value is a procurement scoring item; or the walkway is clean, atmospheric and short-life. For the molded-vs-pultruded split inside FRP, see molded vs pultruded; for the steel alternative, see FRP vs steel.
Do not choose our FRP grating when: the site requires the grating itself to be earthed or bonded; prolonged service temperature sits above the resin glass-transition temperature for the chosen grade; the customer's circularity policy requires recyclable scrap with established market value; or the deflection limit on a short span is so tight that an aluminium section reaches it at lower installed weight than any FRP panel depth we publish.
How to send us the enquiry
Open /frp-grating/ for the product family and /frp-grating-panels/ for the cut-sheet catalogue. Panels leave the plant at 1220×3660 mm or 1220×6096 mm and are cut to your drawing; clips ship alongside in M/C/L/Z form, SS304, SS316 or HDG. In your enquiry, give us the clear span, the design load, the media, the service temperature, and one line on whether the structure must be earthed — that single answer usually decides FRP vs aluminium on the spot. Resin choice (isophthalic, vinyl ester, polyurethane, phenolic) follows from the media. Our plant is ISO 9001 certified, 20+ years in operation, ships to 40+ countries and runs at 10,000+ tonnes a year; the plastic-grating design basis is referenced against DIN 24537 on /standards/din-24537/.