Molded grating is lower-cost with one-piece strength for standard spans; pultruded grating carries heavier loads over longer spans with continuous reinforcement — pick by span and load.
- Best for: choosing between the two FRP grating types
- Choose molded for: cost/standard spans; pultruded for: long spans + heavy load
- Key spec: molded 25–50 mm vs pultruded 25–100 mm, load table
Molded vs Pultruded: Key Differences
Both molded and pultruded FRP grating offer corrosion resistance and lightweight strength, but they have different strengths ideal for different applications.
Manufacturing Process
Molded: Continuous glass fiber rovings in cross pattern, resin injected, hot pressed in molds. One-piece panel with bidirectional strength.
Pultruded: Continuous fibers pulled through resin bath and heated die, forming I-bar or T-bar bearing bars. Cross rods connect bars.
Performance Comparison
| Property | Molded | Pultruded |
|---|---|---|
| Strength Direction | Bidirectional (equal) | Unidirectional (lengthwise) |
| Load Capacity | Medium | High |
| Max Span | 1200mm (38mm) | 2000mm+ (heavy duty) |
| Surface Options | 4 types | 2 types |
| Cutting | Easy, no fraying | Requires care at bars |
| Cost | Lower | Higher |
Application Guide
Choose Molded for: Walkways, platforms, general industrial, areas requiring cutting on-site, bidirectional load areas
Choose Pultruded for: Long spans, heavy loads, truck traffic, high-load industrial platforms, weight-critical applications
Design Standards & Data Basis
All load, span and capacity values in this article are typical/indicative, derived from laboratory tests per NAAMM MBG-01 (FRP Grating Design Manual) methodology. Molded grating values apply a 5:1 factor of safety on ultimate capacity; pultruded grating values apply a 3:1 factor of safety, both measured at static ambient conditions. Impact loads are limited to 50% of stated values; long-term loads require creep adjustment per ASCE Structural Plastics Design Manual. Certified load tables, stamped engineering calculations and third-party test reports are available on request.
For structural sizing of your specific application, contact our engineering team with your load requirements, span and environmental conditions — we provide free structural calculations within 24 hours. Browse our molded grating and pultruded grating product pages for full specifications and resin options.
Typical Allowable Uniform Load (kN/m²) - Molded Grating
The table below consolidates typical allowable uniform live loads for molded isophthalic / vinyl-ester grating at a deflection limit of L/200, with a 5:1 factor of safety on ultimate capacity. Values are typical/indicative per NAAMM MBG-01; certified load tables are available on request.
| Model | Span 600 mm | Span 800 mm | Span 1000 mm | Span 1200 mm | Span 1500 mm |
|---|---|---|---|---|---|
| FG-M2538 (25 mm x 38x38) | 2.5-3.5 | 1.8-2.5 | 1.2-1.8 | 0.8-1.2 | 0.5-0.8 |
| FG-M3038 (30 mm x 38x38) | 4.0-5.0 | 2.8-3.8 | 2.0-2.8 | 1.4-2.0 | 0.9-1.4 |
| FG-M3838 (38 mm x 38x38) | 5.5-7.0 | 4.0-5.0 | 3.0-4.0 | 2.2-3.0 | 1.5-2.2 |
| FG-M3819 (38 mm x 19x19) | 6.5-8.0 | 4.8-6.0 | 3.6-4.6 | 2.6-3.5 | 1.8-2.6 |
| FG-M5038 (50 mm x 38x38) | 9-12 | 6.5-8.5 | 5.0-6.5 | 3.8-5.0 | 2.6-3.6 |
Typical/indicative values per NAAMM MBG-01; certified table on request. Ranges reflect resin system, mesh tolerance and fabrication variation. For forklift or truck traffic, use pultruded I-bar grating.
Typical Allowable Uniform Load (kN/m²) - Pultruded I-bar Grating
| Model | Span 1000 mm | Span 1500 mm | Span 2000 mm | Span 2500 mm |
|---|---|---|---|---|
| FG-P5038 (50 mm I-bar x 38 mm spacing) | 22-28 | 10-14 | 5.5-7.5 | 3.5-5.0 |
| FG-P6538 (65 mm I-bar x 38 mm spacing) | 40-50 | 20-26 | 11-15 | 7-10 |
Unidirectional strength measured along bearing bars; spans must be taken between supports along the bar direction. Typical/indicative per NAAMM MBG-01; certified table on request.
Model Naming: Thickness x Mesh Reference
ZEALL molded FRP grating is designated by panel thickness x mesh opening. The standard catalog covers four depths (25 / 30 / 38 / 50 mm) and three mesh sizes (38x38, 19x19, 50x50 mm). A typical designation is "38 mm Molded Grating x 38x38 mm mesh" (model code FG-M3838). Common references:
| Model code | Thickness | Mesh | Duty class | Typical use |
|---|---|---|---|---|
| FG-M2538 | 25 mm | 38x38 mm | Light | Drainage covers, light walkways |
| FG-M3038 | 30 mm | 38x38 mm | Medium | General walkways, ramps |
| FG-M3838 | 38 mm | 38x38 mm | Standard | Industrial platforms, standard service |
| FG-M3819 | 38 mm | 19x19 mm | Standard mini-mesh | Tool handling, heel-safe walkways |
| FG-M5038 | 50 mm | 38x38 mm | Heavy | Forklift areas, long spans |
| FG-P5038 | 50 mm I-bar | 38 mm bar spacing | Heavy pultruded | Heavy-duty platforms, truck traffic |
Typical Structural Parameters (I / S / E)
The table below gives typical flexural stiffness ranges for FRP grating profiles. Values are typical per NAAMM MBG-01 and are not a substitute for a certified mill test report. E depends on resin system (isophthalic polyester approx. 10-12 GPa; vinyl ester approx. 12-15 GPa); I and S scale with bar depth and profile shape.
| Profile | E flexural (GPa) | I (cm⁴ / m width) | S (cm³ / m width) |
|---|---|---|---|
| 25 mm molded grid | 10-12 | 2.5-4.0 | 2.0-3.2 |
| 30 mm molded grid | 10-12 | 4.5-7.0 | 3.2-4.8 |
| 38 mm molded grid | 11-13 | 8-13 | 5.0-7.5 |
| 50 mm molded grid | 11-14 | 16-26 | 8.5-13 |
| 50 mm I-bar pultruded | 12-15 | 55-85 | 22-32 |
Typical values per NAAMM MBG-01; certified values per project-specific mill test report on request.
Browse our product pages for full specifications: FRP molded grating · FRP pultruded grating.
Frequently Asked Questions
FRP (Fiberglass Reinforced Plastic) grating is a molded or pultruded fiberglass composite grid used for corrosion-resistant walkways, platforms and floorings. It combines glass fiber reinforcement with thermoset resin (polyester, vinyl ester, epoxy) for superior strength-to-weight ratio, zero rust and 20+ year service life.
