Molded vs Pultruded FRP Grating

Two manufacturing methods, two strength patterns - and a clear way to pick between them.

Two Ways to Make FRP Grating

Both types are made from E-glass fiberglass reinforcement and thermoset resin, and both share the basic advantages of the material: corrosion resistance, high strength-to-weight ratio, slip resistance and low maintenance. The difference is how the fiberglass is laid and how the panel carries load.

Molded grating is cast in a one-piece mold: continuous fiberglass strands are laid in both directions and bound with resin, so the finished panel carries load bi-directionally - along and across the panel.

Pultruded grating is assembled: the load-bearing bars are made by pulling continuous fiberglass rovings through a resin bath and a heated die, then joined with cross rods. The fiber runs along the bar, so strength is concentrated in one direction - the direction you span.

Molded vs Pultruded: Side by Side

	Molded grating	Pultruded grating
Construction	Cast in one piece; fiberglass strands run in both directions	Load bars pulled through a heated die, joined with cross rods
Load direction	Bi-directional - carries load both ways	Unidirectional - strongest along the load bars
Typical open area	40% to 78% depending on mesh	12% to 50% depending on bar spacing
Typical panel	Up to 1220 x 4000 mm; some meshes also 1524 x 4000 mm and 915 x 3050 mm	1220 or 915 mm wide, 3050 or 6100 mm long
Weight range	About 14.6 to 23.7 kg/m² for standard panels; heavy-duty mesh 42 kg/m²	About 14.5 to 70.4 kg/m² depending on depth and bar thickness
Typical use	Walkways, platforms, stair treads, trench covers, general industrial flooring	Long spans, heavy concentrated loads, cooling towers, high-load structures

How to Choose

Load in both directions, moderate spans, standard panels: molded grating such as 19*19H30 or 38*38H30.
Long spans or heavy concentrated loads: pultruded grating - the I, T and HL bar series - where load runs along the bars.
Maximum open area for drainage, snow or vision: molded 50*50H50 with 78% open area.
Very heavy loads on closely spaced supports: heavy-duty molded 38*38H50 at 42 kg/m².
Mixed layouts: pultruded grating for the main spans with molded grating for infill bays and walkways is a common combination.
Corrosive environments: either type works; the resin system decides the chemical and temperature fit.

The final choice is usually decided by the deflection limit for your span, not by a general rule: compare the load tables of each candidate against the same working load.

See our FRP grating load capacity guide for how to read those tables, and the specifications guide for mesh, thickness and panel sizes.

Our Ranges

Molded: 19*19H30 (40% open area, 19.1 kg/m²), 38*38H30 (68%, 14.6 kg/m²),

50*50H50 (78%, 23.7 kg/m²) and 38*152H38 with load-bearing bars running lengthwise (67%, 15.92 kg/m²).

Pultruded: I-4010 (25 mm bearing bar, 50% open area), T-1210 and T-1215 (12% open area, closed-type surface),

T-5020 and the heavy HL-4020 (70.37 kg/m²).

Browse the full FRP grating range, or see the pultruded product family on our pultruded gratings page.

Tell us your span, load and environment and we will recommend the type and panel size - contact us at admin@greenlogy.cn.

Frequently Asked Questions

What is the difference between molded and pultruded FRP grating?

Molded grating is cast in one piece with fiberglass strands running in both directions, so it carries load bi-directionally.

Pultruded grating is assembled from load bars made by pulling continuous fiberglass through a heated die, giving very high strength along the bar direction. Molded suits general walkways and platforms; pultruded suits long spans and heavy concentrated loads.

Which type is stronger?

They are strong in different ways. Molded panels carry load in both directions; pultruded bars carry much higher load along a single direction and span further before deflecting too much.

For a given span and load the choice is normally decided by the deflection limit, so compare the load tables of each type.

Which one resists corrosion better?

Both are made with corrosion-resistant thermoset resin and E-glass reinforcement, and neither rusts. The deciding factor is the resin system rather than the manufacturing method: orthophthalic, isophthalic, vinyl ester and phenolic systems each suit different chemicals and temperatures.

Can the two types be combined in one platform?

Yes. A common design uses pultruded grating for the main load-bearing spans and molded grating for infill bays, walkways and stair treads. Send us your platform drawing and we can advise on a mixed layout.

How do I choose between them for my project?

Send us the span, the working load and the environment. As a rule of thumb, spans up to about 900 mm with moderate loads suit molded panels such as 19*19H30 or 38*38H30, while longer spans and heavy loads point to the pultruded I, T or HL series.

We will recommend the type and panel size for your case.