Molded vs Pultruded FRP Grating: Which Should You Specify?

The Difference That Actually Matters

Molded FRP grating is formed as one panel. The glass reinforcement and resin are placed in a mold, the panel cures, and the finished product is an integral grid. There is no mechanical joint running across the panel between separate bearing bars. That construction allows the grid to distribute or carry load in two directions, which is why framed openings and walkways with changing load directions often begin with molded grating.

Pultruded FRP grating is an assembly. Continuous glass reinforcement is pulled through resin and a heated die to create I, T or WT bearing bars. Holes are made along those bars, cross rods are inserted at intervals, and the bars are fixed together. The principal load path is along the bars. The assembly can be made to the ordered width and bearing-bar length, but the bars must reach supports at their ends.

That is the decision in one paragraph: look at where the panel can reach its supports, then look at the load and deflection limit. “Molded or pultruded?” is not a material-quality question, and one family is not universally stronger, cheaper or longer-lasting.

Written by our team and checked against the factory product schedules and technical records. Updated 17 October 2026. The limits of the available evidence are stated below.

The distinction is also why a page that lists only manufacturing differences is incomplete. The manufacturing process changes what happens at a cutout, what happens if the panel is rotated, how a clip is selected and what the quotation has to include. Those are the buyer’s real decision points, so they are treated separately below.

Load Direction and Support Layout

Start with the frame, not the panel. Mark every edge that actually bears, the unsupported distance between supports, the fixed height and the direction in which a long panel can be carried into the space. A large panel outline does not prove that the panel is supported in the right place.

For molded grating, the integral mesh commonly makes four-edge framing the natural arrangement. The mesh can distribute a local load into adjacent bars in more than one direction. That is an advantage on a framed walkway, but it does not remove the structural review. The panel still needs matched load and deflection data for its thickness, mesh, resin and support condition. A square mesh does not make every cut piece equivalent.

For pultruded grating, the bearing bars must run from one effective supporting edge to the opposite supporting edge. A four-sided frame is not a problem in itself, provided the bars reach the supports and the assembly is suitable for the load. The error appears when a rectangular panel is rotated to fit a space, because the bars no longer run in the direction that was selected. Mark the bearing direction on the drawing and on the delivered piece.

The useful drawing information is therefore not just “platform 3 m × 2 m”. It is the support plan, the clear span in each direction, the panel joint positions, the bearing width and the location of every opening. If those values are not shown, two factories can quote different structures while both believing they have priced the same platform.

How to Compare Spans Without Comparing Thickness

Equal thickness is the most common false comparison in this product category. A 38 mm molded panel and a 38 mm pultruded bar have different profiles, different reinforcement paths and different failure modes. Even a “25 mm pultruded” series can have several pitches and open areas, with different mass and behaviour. The thickness alone does not identify the product.

A usable span comparison needs the same information on both sides:

• The clear distance between the actual supports, using the same definition for both offers.
• The bearing-bar direction and the support condition for each candidate.
• The load type and value: uniform area, point, line, wheel or equipment load.
• The load contact area or position where the case is not uniformly distributed.
• The permitted deflection, including any absolute limit or span fraction.
• The exact molded thickness and mesh, or pultruded series, pitch and bar direction.
• The resin, surface and finished cut layout that will be delivered.

The structural answer is often controlled by deflection before the headline load value is reached. A table that lists only “maximum load” can therefore look more generous than a panel that would visibly sag beyond the project limit. Ask which load produced the listed deflection and whether the table applies to the finished panel, including cuts and openings.

For molded grating, our published load guidance identifies which thickness, mesh and support condition a data row belongs to. For pultruded grating, the proposed I, T or WT section and pitch have to match the table or calculation being used. Neither family can be approved from the weight per square metre; mass is a handling and self-weight figure.

If the project has a long clear span, pultruded grating is usually the first family to examine because the deeper directional bar can be efficient over that span. If the frame is short, heavily divided or carrying cutouts in several directions, molded grating is usually the first family to examine. “Usually” is doing real work in those sentences: the load case still decides.

Openings, Cutting and Edge Treatment

Molded grating can be cut around a pipe, equipment foot or irregular opening, and factory cutting is often preferable to site fabrication. But the phrase “molded grating can be cut in any direction” stops too early. The cut removes part of the grid, interrupts the local load path and exposes a new edge. The remaining panel has to be supported around the opening and handled safely.

For pultruded grating, the cut may remove one or more bearing bars. The remaining bar ends need a support or a designed edge arrangement; sealing the cut surface protects the laminate but does not reconnect the structural path. An opening may also change how a concentrated load is transferred into the adjacent bars. Review the opening on the assembly drawing, not after the panel is cut.

Both products can receive factory-cut pieces, drilling, piece marks and requested resin edge sealing. The difference is what the cut does to the load path. In a molded panel, the remaining grid around the opening is the starting point for the review. In a pultruded panel, the bar ends around the opening are the starting point. Neither review is finished by applying sealant.

Also separate the opening from the fixing. A clip holds the panel down; it does not create a bearing support. If a cut piece rests on a narrow frame or overhangs an opening, adding a clip does not complete the load path. The support detail has to be designed with the cutout.

Impact, Chemicals and Fire Are Separate Questions

The resin-rich molded mesh is often the preferred starting point where dropped tools or local impact are part of normal use. The dense grid can absorb local damage and distribute it into the surrounding panel. That is a useful general distinction, not a guarantee for every impact. A heavy dropped object, a damaged support or a deep cut can still require replacement.

Pultruded grating has a more directional structure and higher stiffness along the bearing bars. A local impact on a bar or cross-rod connection has to be assessed against the section and the consequence of damage. A high longitudinal modulus is not the same as a high tolerance for a point impact.

Chemical performance is not decided by the words “molded” or “pultruded”. It is decided by the resin, laminate, exposure and finished configuration. Isophthalic unsaturated polyester with alumina filler is the economical starting point in our published molded price, but it is for ordinary environments. Vinyl ester, epoxy and phenolic are separate directions, each with its own evidence and commercial scope. A resin name also does not establish a fire class, smoke result or chemical approval for every thickness and panel.

The same separation applies to fire, static, UV and barefoot use. State the standard or acceptance criterion, the concentration and temperature, the contact type and the test method. A report that applies to a material sample may not apply to the finished panel. This is why our 2024 material report is presented as material-level evidence, not as a load rating or fire approval for every product.

Surface, Color and Resin Are Configuration Choices

Molded grating has a broad surface range because the walking surface is formed with the panel. Concave, grit, inlaid grit, milled top, covered and other formats are selected according to the route, cleaning method and appearance. Pultruded grating finishes are confirmed with the bar assembly. A surface selected for one family is not automatically available on the other.

Color is a pigment choice, not a resin rating. Yellow is common where an access route should be visible; green, gray, blue and black are also used. A yellow panel does not prove fire performance, anti-static performance or slip resistance. A grit surface is a texture, not a certified slip class. Ask for the test and acceptance basis that the project actually requires.

For outdoor service, state the UV exposure and appearance expectation. For wash-down areas, include the cleaning chemicals and method. For a route used by small-wheeled trolleys or mobility equipment, describe the wheel and clear-opening requirement as well as the top finish. The same resin and surface combination can be right for a walkway and wrong for a chemically exposed platform.

Our resin selection guide sets out the exposure questions, and the surface and treatment guide separates texture, drainage and functional requirements.

Installation and Fixing: How the Wrong Fit Happens

The first installation check is before dispatch: confirm that the piece marks, dimensions, openings and bearing direction match the approved drawing. A panel can have the correct outside dimensions and still be the wrong piece if the bearing bars run the other way or a pipe opening is on the opposite side.

At fit-up, set the panels in place without fixing first. Check bearing on every intended support, the joints, the cut edges, the top face and the opening clearance. For pultruded grating, confirm that the bearing bars run the way the drawing says. For molded grating, confirm the intended top surface and keep the joint pattern consistent across adjacent panels.

M, L and C clips restrain panels and join adjacent edges. Match the clip to the panel height, bar width and support type. The clip is not a substitute for bearing, and it is not a structural repair for a damaged panel. For removable covers, the lifting method and fixing arrangement also belong to the order review.

For more detailed checks, use the installation guide, the clip guide and the cutting and sealing guide. The installation page explains why a panel that looks level can still be unsupported or incorrectly oriented.

How to Compare the Total Price

The published molded price is a useful reference because it fixes several variables at once. Our standard 38 × 38 mm molded panels are listed at USD 10.5/m² for 25 mm, USD 12.0/m² for 30 mm and USD 15.1/m² for 38 mm, ex-works, using isophthalic unsaturated polyester with alumina filler. A full 1220 × 3660 mm panel is 4.4652 m², so the 25 mm panel starts at roughly USD 46.9 before cutting, clips, packing and freight.

That price is not a universal FRP grating price. It is a molded standard-panel reference in an ordinary environment. It is not the price of vinyl ester, epoxy, phenolic, a special surface or a pultruded assembly. It also carries a service-life boundary: our experience with that economical formulation is about three years of use, with cracking possible from around one year, and it is not intended for strong corrosion. A project that needs a different resin must be quoted as a different configuration.

Pultruded grating does not have one honest area rate. The price changes with the I, T or WT series, bar height, pitch, resin, surface, panel length, cross-rod layout, openings, edge treatment, clips, packing and delivery. Two panels with the same outside size can have different bar spacing and weight. A quotation should identify the actual section and the delivered piece list so it can be compared with another offer.

The next layer is the total installed scope. Pultruded grating may reduce the number of supports or the steel below a long platform. Molded grating may make a complicated cut layout easier to fabricate and fit. Both may require clips and packing; both may need edge treatment and both can be delayed by a drawing that changes after fabrication. Compare the two options with the same support steel, installation assumptions and delivery terms.

The pricing guide explains the molded price schedule in more detail. The cutting and sealing guide explains why a simple cut, a complex opening and an edge seal belong in different lines of the quotation.

Which One Should You Specify?

Use molded grating as the first candidate when the frame supports the panel on all four edges, the route or equipment layout changes direction, the project has several irregular cutouts, or the economical standard-panel range already covers the load and span. Verify the actual mesh, thickness, resin, surface and deflection limit before approving it.

Use pultruded grating as the first candidate when the support beams run one way, the clear span is long enough that a directional bar is useful, the panel length is fixed by the platform layout, or the project needs a custom assembly with a marked bearing direction. Verify the section, pitch, bar direction, cross-rod layout and support at every bar end.

When the frame is a mixed layout, the safest response is not to guess. Prepare one drawing and ask for both families to be checked against it. That lets the supports, load, deflection, resin and delivered scope be compared without turning the decision into a slogan.

Manufacturer Experience and the Limits of the Evidence

We manufacture molded panels and pultruded bars at our works in Jingxing Mining District, Shijiazhuang, Hebei. The factory can coordinate panel production, cutting, drilling, requested edge sealing and clip supply in the same order. A standard 3 × 3 cell sample is available free of charge, with freight paid by the customer; custom resin, color or surface samples are charged.

For example, the available 2024 report, HZTC/BG-24051102 dated 17 May 2024, records appearance, Barcol hardness 45, water absorption 0.335%, oxygen index 28.5%, tensile strength 74.2 MPa and a load test at a design load of 4 kN/m² over a 600 mm span. It does not name the model, thickness, mesh or resin. It therefore supports a material-level discussion, not a claim that every molded or pultruded panel has the same capacity or fire performance.

Production normally runs 15–30 calendar days from receipt of the deposit. Export packing generally uses EPE foam and stretch film, with wooden pallets or iron supports. Trade term, packing, documents, shipment and the final piece list are stated in the quotation. The quality and documentation page explains how to read that evidence without turning a general report into a product approval.

Manufacturer pages such as Bedford’s comparison, Strongwell’s overview and Fibergrate’s older comparison are useful for understanding the general categories. Their structural values, resin systems and certifications apply to their products, not automatically to ours. Use them to frame the questions, then verify our actual configuration.

Send the support drawing and load case and we can identify which family is worth comparing before a quotation is prepared.