---
title: "Fiberglass Trench Covers & Drain Grates: Loads & Sizes"
description: "Fiberglass trench grating, trench covers and drain grates: match the load class to foot, cart or vehicle traffic, size covers to the trench, see US prices."
url: https://www.strongrate.us/applications/trench-covers-and-drain-grates/
markdown: https://www.strongrate.us/applications/trench-covers-and-drain-grates.md
published: 2026-10-16
updated: 2026-10-17
---

[Home](https://www.strongrate.us/) › [Fiberglass grating](https://www.strongrate.us/fiberglass-grating/) › [Trench covers & drain grates](https://www.strongrate.us/applications/trench-covers-and-drain-grates/)

# Fiberglass Trench Grating: Trench Covers and Drain Grates

_Updated Oct 17, 2026_

Choose fiberglass trench grating by the heaviest traffic that crosses it: pedestrian grating sized from a load table where only people walk, and heavy-duty grating with a wheel-load rating where carts, cars or forklifts cross. US suppliers rate heavy-duty FRP grating up to AASHTO H-20; Strongrate’s catalog gives wheel-load spans for its HI high-load pultruded grating.

## Which load class does fiberglass trench grating need?

Where only people cross, size the grating from a load table at the trench’s clear span. US guide specifications set walkway criteria from a 60 psf (2.9 kPa) uniform load with a maximum 1/4" (6.4 mm) deflection to 100 psf (4.8 kPa) uniform or a 300 lb (1.3 kN) concentrated load at 3/8" (9.5 mm) or L/120, whichever is less. Makers advise halving tabulated capacities for impact or dynamic loads, such as carts and hand trucks.

Where wheels cross, use heavy-duty grating with a published wheel-load rating. US suppliers rate high-load molded and deep pultruded FRP grating for vehicle traffic up to AASHTO H-20 loading, and one maker’s heavy-duty span table is based on the wheel loads below with 0.25" (6.4 mm) deflection.

**Fiberglass trench grating wheel loads in one US maker’s heavy-duty span table (Bedford), with what Strongrate’s catalog covers**

| Design wheel | Wheel load, lb (kN) | Strongrate catalog |
| --- | ---: | --- |
| Automobile wheel | 2,220 lb (9.9 kN) [note 1] | Automobile wheel: spans per HI type [note 2] |
| 5-ton forklift wheel | 13,480 lb (60.0 kN) [note 1] | 1-, 3- and 5-ton forklift wheels: spans per HI type [note 2] |
| AASHTO truck wheel (H-20) | 20,800 lb (92.5 kN) [note 1] | AASHTO truck wheel: spans per HI type [note 2] |

_Strongrate’s catalog bases its HI spans on 1/4" (6.4 mm) deflection and a safety factor of 3.0. Where wheels cross, the span is confirmed in your quote and needs your engineer’s review._

Notes:

1. Another maker’s method, not Strongrate data.
2. Values as printed in the factory catalog (2023); confirmed in your quote and submittal drawings.

Typical heavy-duty (HLC) molded grating from US makers has a 1" × 2" (25 × 51 mm) mesh with 48–51% open area, and weighs about 6.0–6.2 lb/ft² (29.3–30.3 kg/m²) at 1-1/2" (38 mm) depth and 8.4 lb/ft² (41.0 kg/m²) at 2" (51 mm). Strongrate’s catalog lists heavy-duty 1-1/2" × 1-1/2" (38 × 38 mm) molded grating at 2" (50 mm), 2-3/8" (60 mm), 2-9/16" (65 mm) deep, weighing 8.2–10.7 lb/ft² (40.0–52.0 kg/m²), and a 1" × 2" (25 × 51 mm) mesh at 1-1/2" (38 mm), 2" (50 mm) deep; it gives these static deflection tables only, not wheel-load ratings.

For wheel loads the catalog points to its HI high-load pultruded I-bar grating, 10 types from 1" (25 mm) to 3" (76 mm) deep and 4.3–15.1 lb/ft² (21.0–73.6 kg/m²). Their deflection tables are on [fiberglass grating load tables](https://www.strongrate.us/resources/fiberglass-grating-load-tables/) and the product family on [pultruded fiberglass grating](https://www.strongrate.us/pultruded-fiberglass-grating/).

**Strongrate HI high-load pultruded grating for vehicle areas: catalog data**

| Type | Bar shape | Depth | Bearing-bar centers | Cross-bar centers | Open area | Weight |
| --- | --- | --- | --- | --- | ---: | ---: |
| HI-4710 [note 1] | I-bar, high load | 1" (25 mm) [note 1] | 1.19" (30.2 mm) [note 1] | 6" (152 mm) [note 1] | 47% [note 1] | 5.7 lb/ft² (27.6 kg/m²) [note 1] |
| HI-4715 [note 1] | I-bar, high load | 1-1/2" (38 mm) [note 1] | 1.19" (30.2 mm) [note 1] | 6" (152 mm) [note 1] | 47% [note 1] | 8.2 lb/ft² (40.0 kg/m²) [note 1] |
| HI-4720 [note 1] | I-bar, high load | 2" (50 mm) [note 1] | 1.19" (30.2 mm) [note 1] | 6" (152 mm) [note 1] | 47% [note 1] | 11.2 lb/ft² (54.5 kg/m²) [note 1] |
| HI-4725 [note 1] | I-bar, high load | 2-1/2" (64 mm) [note 1] | 1.19" (30.2 mm) [note 1] | 6" (152 mm) [note 1] | 47% [note 1] | 12.6 lb/ft² (61.6 kg/m²) [note 1] |
| HI-4730 [note 1] | I-bar, high load | 3" (76 mm) [note 1] | 1.19" (30.2 mm) [note 1] | 6" (152 mm) [note 1] | 47% [note 1] | 15.1 lb/ft² (73.6 kg/m²) [note 1] |
| HI-5810 [note 1] | I-bar, high load | 1" (25 mm) [note 1] | 1.50" (38.1 mm) [note 1] | 6" (152 mm) [note 1] | 58% [note 1] | 4.3 lb/ft² (21.0 kg/m²) [note 1] |
| HI-5815 [note 1] | I-bar, high load | 1-1/2" (38 mm) [note 1] | 1.50" (38.1 mm) [note 1] | 6" (152 mm) [note 1] | 58% [note 1] | 6.5 lb/ft² (31.8 kg/m²) [note 1] |
| HI-5820 [note 1] | I-bar, high load | 2" (50 mm) [note 1] | 1.50" (38.1 mm) [note 1] | 6" (152 mm) [note 1] | 58% [note 1] | 8.7 lb/ft² (42.5 kg/m²) [note 1] |
| HI-5825 [note 1] | I-bar, high load | 2-1/2" (64 mm) [note 1] | 1.50" (38.1 mm) [note 1] | 6" (152 mm) [note 1] | 58% [note 1] | 10.0 lb/ft² (48.9 kg/m²) [note 1] |
| HI-5830 [note 1] | I-bar, high load | 3" (76 mm) [note 1] | 1.50" (38.1 mm) [note 1] | 6" (152 mm) [note 1] | 58% [note 1] | 12.0 lb/ft² (58.6 kg/m²) [note 1] |

_As printed in Strongrate’s 2023 product catalog; confirmed in your quote and submittal drawings. Weights and open areas are from the catalog’s summary table; some of its detail cards print different values._

Notes:

1. Values as printed in the factory catalog (2023).

## How do I size a trench cover to the trench?

The grating spans across the trench, so its clear span is the trench width between the supporting ledges. Give each edge at least 1-1/2" (38 mm) of bearing on its support, per Bedford’s fastener guidance. Molded grating is cast as one piece with strength in both directions. Pultruded grating is built from bearing bars joined by cross rods, and on stock panels the bearing bars run parallel to the panel length, so cut pultruded covers with the bars spanning across the trench.

**Panel sizes for cutting fiberglass trench covers: industry norms and Strongrate’s catalog**

| Grating | Common US panel sizes, ft (mm) | Strongrate catalog sizes |
| --- | --- | --- |
| Molded | 3 ft × 10 ft, 4 ft × 8 ft, 4 ft × 12 ft and 5 ft × 10 ft (915 × 3050, 1220 × 2440, 1220 × 3660 and 1525 × 3050 mm) [note 1] | 5 ft × 13.12 ft (1524 × 4000 mm); 4 ft × 12 ft (1220 × 3660 mm); 4 ft × 8 ft (1220 × 2440 mm); 3 ft × 10 ft (921 × 3050 mm) (1-1/2" square mesh; other meshes vary) [note 2] |
| Heavy-duty molded | 4 ft × 6 ft (1220 × 1830 mm) [note 1] | 1-1/2" heavy duty: 4 ft × 12 ft (1220 × 3660 mm); 4 ft × 8 ft (1220 × 2440 mm); 3 ft × 10 ft (921 × 3050 mm). 1" × 2" (25 × 51 mm) mesh: 4 ft × 6 ft (1220 × 1830 mm); 4 ft × 12 ft (1220 × 3660 mm) [notes 2, 3] |
| Pultruded | 3, 4 or 5 ft (915, 1220 or 1525 mm) wide, up to 20 ft (6.10 m) long [note 1] | Up to 5 ft × 20 ft (1524 × 6100 mm) [note 2] |

_Strongrate sizes are as printed in its 2023 catalog. All meshes and depths: [fiberglass grating sizes, weight and open area](https://www.strongrate.us/resources/fiberglass-grating-sizes-weight-and-open-area/)._

Notes:

1. Strongrate sizes are stated in your quote.
2. Values as printed in the factory catalog (2023); confirmed in your quote and submittal drawings.
3. Deflections as printed in the factory catalog (2023), static loads at ambient temperature; confirm for your span in the submittal before final design.

Covers are cut with carbide or diamond tooling, and guide specifications require every cut edge to be sealed with resin. One US supplier states that openings up to 10" (254 mm) can be cut in molded grating without added support, depending on depth; confirm with the load table and an engineer. Step-by-step: [how to cut fiberglass grating](https://www.strongrate.us/resources/how-to-cut-fiberglass-grating/).

## What frames and hold-downs do fiberglass trench covers need?

Covers bear on a ledge or embedded frame along both edges of the trench. Strongrate’s catalog lists embedded angles among its pultruded structural shapes. Fasten covers with hold-down clips: US guide specifications call for Type 316 stainless steel clips spaced no more than 4 ft (1.22 m) apart, with at least four per piece of grating. See [fiberglass grating clips](https://www.strongrate.us/accessories/fiberglass-grating-clips/) and [how to install fiberglass grating](https://www.strongrate.us/resources/how-to-install-fiberglass-grating/).

Where the trench must be closed to debris or spills, use covered (solid-top) grating. Bonding a gritted cover plate, typically 1/8" (3.2 mm) or 1/4" (6.4 mm) thick, makes open grating roughly 30–50% stiffer, according to US supplier literature. Strongrate’s catalog lists solid covers with a checker or grit finish for molded and pultruded grating.

## Where is fiberglass used for drain grates and cable trenches?

Fiberglass is non-conductive, and suppliers market fiberglass plate and grating for electrical flooring; for a cable trench cover, choose the load class as above. A US distributor recommends molded grating for trench covers, general flooring and chemical plants. Pool and spa drain grates are a separate case: they fall under the Virginia Graeme Baker Act, and US makers certify such grating to ASME A112.19.8a-2008. Strongrate has no documented VGBA certification, so do not use it for pool or spa drains.

## What do fiberglass trench covers cost?

Strongrate quotes trench covers per project in USD, with the Incoterm and quote date. For scale, a US home-improvement retailer listed a 2 ft × 2 ft (610 × 610 mm) gritted molded panel, 1" (25 mm) deep, at $48.19, about $12.05 per sq ft, on Oct 15, 2026, and published FRP price guides (2025 or undated, read Oct 15, 2026) put heavy-duty grating at up to $45 per sq ft. These are market benchmarks, not Strongrate prices. See [fiberglass grating price per square foot](https://www.strongrate.us/pricing/fiberglass-grating-price/).

Strongrate grating is made in Nantong, China, so it does not qualify for federally assisted water and wastewater projects covered by Build America, Buy America (BABA), such as State Revolving Fund work; privately funded plants are not subject to BABA. See [Buy America (BABA) and imported FRP grating](https://www.strongrate.us/buy-direct/buy-america-baba/).

## Frequently asked questions

### Can fiberglass trench grating take forklift traffic?

Only heavy-duty grating rated for the forklift’s wheel load at your span; one US maker designs its heavy-duty table to a 13,480 lb (60.0 kN) 5-ton forklift wheel. Strongrate’s catalog gives HI high-load pultruded spans for 1-, 3- and 5-ton forklift wheels, confirmed in your quote; your engineer should review the span. Send the wheel load and tire size with a [quote request](https://www.strongrate.us/request-quote/).

### Should trench covers be molded or pultruded grating?

A US distributor recommends molded grating for trench covers, and molded has strength in both directions. Pultruded grating is marketed as about twice as stiff and spans farther, but its bearing bars must run across the trench. Compare them in [molded vs pultruded grating](https://www.strongrate.us/compare/molded-vs-pultruded-fiberglass-grating/).

### What should I send for a trench cover quote?

Trench width and length, the traffic that crosses it (foot, cart or vehicle, with wheel load and tire width), open or covered top, surface, resin, the ledge or frame detail, quantity and delivery ZIP code. Send it through [request a quote](https://www.strongrate.us/request-quote/).

## Related pages
- [Fiberglass grating](https://www.strongrate.us/fiberglass-grating/): What fiberglass (FRP) grating is, how molded and pultruded types differ, standard panel sizes and price ranges, and the grating options Strongrate makes.
- [Car wash grating](https://www.strongrate.us/applications/car-wash-grating/): Fiberglass grating for car wash pits, trench drains and bays: where wheel loads need heavy-duty grating, surface and resin choices, how to estimate quantity, and a dated US price benchmark.
- [Fiberglass dock and marina grating](https://www.strongrate.us/applications/dock-and-marina-grating/): Fiberglass grating for docks, piers and marinas: resin and UV choices for salt water, barefoot-friendly surfaces, open area, panel sizes and weights, load tables, certificates and price benchmarks.
- [2" molded fiberglass grating](https://www.strongrate.us/molded-fiberglass-grating/2-inch-square-mesh/): When to specify 2-inch-deep molded fiberglass grating with a 2-inch square mesh: Strongrate catalog weight, open area, panel sizes and deflection tables, and how to order it.
- [Fiberglass grating load tables](https://www.strongrate.us/resources/fiberglass-grating-load-tables/): The load tables in Strongrate’s catalog for each product, and how to read fiberglass grating load tables: uniform and line loads by span, deflection limits and safety factors.

**Request a quote:** https://www.strongrate.us/request-quote/ · Order a sample: https://www.strongrate.us/samples/ — Send trench width, length, traffic and wheel loads for a trench cover quote. Quotes within 1 business day (US Central time); the reply confirms routing and next steps.

## Sources
- [Grating Pacific, high load capacity grating; Direct Metals heavy-duty grating page](https://gratingpacific.com/product/high-load-capacity-grating/) (accessed Oct 15, 2026)
- [Bedford PROGrate heavy-duty pultruded grating (allowable-span basis and wheel loads)](https://bedfordreinforced.com/products/proseries/prograte/prograte-heavy-duty-pultruded-grating/) (accessed Oct 15, 2026)
- [Strongwell Section 06 74 13 pultruded spec (revised Nov 2024); Fibergrate molded guide spec (walkway design loads)](https://www.strongwell.com/wp-content/uploads/2014/10/StrongwellSpecs-FRP-Pultruded-Grating-and-Treads.pdf) (accessed Oct 15, 2026)
- [Grating Pacific, Industrial Pultruded FRP Load Tables (impact loads)](https://gratingpacific.com/wp-content/uploads/2019/10/Industrial-Pultruded-FRP-Load-Tables-1.pdf) (accessed Oct 15, 2026)
- [Fibergrate details PDF; Strongwell DURAGRATE; Bedford catalog (heavy-duty molded grating)](https://www.fibergrate.com/media/181504/molded-frp-grating-details-and-options.pdf) (accessed Oct 15, 2026)
- [Strongrate website page titles (search index): heavy-duty molded, heavy-duty pultruded and cover grating; structural shapes](http://www.strongrate.com/product-heavy-duty-frp-grating.html) (accessed Oct 15, 2026)
- Strongrate product catalog “Your Best FRP Solution” (image PDF, Sep 2023), supplied by the site owner (accessed Oct 17, 2026)
- [Bedford PROGrid and PROGrate Grating Catalog 2025 (minimum bearing; pool drain grating)](https://bedfordreinforced.com/wp-content/uploads/2026/03/2118-2025-Bedford-Grating-Catalog-Whole_LR.pdf) (accessed Oct 15, 2026)
- [Fibergrate FAQ (molded and pultruded construction)](https://www.fibergrate.com/resource-center/faq/) (accessed Oct 15, 2026)
- [McNichols pultruded grating spec page (MS-I-6010)](https://www.mcnichols.com/fiberglass-grating/pultruded/fiberglass-fg-f1i60ysc) (accessed Oct 15, 2026)
- [Fibergrate molded FRP products brochure; McNichols molded catalog (panel sizes, resin systems)](https://www.fibergrate.com/media/166803/molded-frp-products-brochure.pdf) (accessed Oct 15, 2026)
- [DNV Type Approval Certificate TAF0000191 Rev. 1 (resins of the six listed models)](https://www.shipserv.com/Shipserv/pages/profiles/261792/certifications/20241010142426209-DNV-GL-Certificate-GRATINGS-Strongrate.pdf) (accessed Oct 15, 2026)
- [Strongwell grating page (pultruded panel sizes)](https://www.strongwell.com/products/grating/) (accessed Oct 15, 2026)
- [Fibergrate molded grating guide specification (cutting, sealing and hold-down clips)](https://www.fibergrate.com/media/180193/fibergrate-frp-molded-grating-specs.pdf) (accessed Oct 15, 2026)
- [American Grating molded FRP grating page (openings without added support)](https://www.americangrating.com/molded-frp-grating.aspx) (accessed Oct 15, 2026)
- [Direct Metals covered grating page; Strongwell DURAGRATE brochure](https://www.directmetals.com/products/fiberglass-grating/fiberglass-covered-grating/) (accessed Oct 15, 2026)
- [Direct Metals product applications (electrical flooring)](https://www.directmetals.com/resources/product-applications/) (accessed Oct 15, 2026)
- [Direct Metals blog, Pultruded vs molded fiberglass grating (Jan 15, 2026)](https://www.directmetals.com/blog/pultruded-fiberglass-grating-vs-molded-fiberglass-grating-which-is-right-for-your-needs/) (accessed Oct 15, 2026)
- [Fibergrate pultruded grating page (stiffness compared with molded)](https://www.fibergrate.com/products/pultruded-grating/) (accessed Oct 15, 2026)
- [EPA, Build America, Buy America (CWSRF page)](https://www.epa.gov/cwsrf/build-america-buy-america-baba) (accessed Oct 15, 2026)
- [EPA, Build America, Buy America FAQs for manufacturers (Jun 2025)](https://www.epa.gov/system/files/documents/2025-06/baba-faqs-for-manufacturers.pdf) (accessed Oct 15, 2026)
- US home-improvement retailer product listing (2 ft × 2 ft molded panel) (accessed Oct 15, 2026)
- [FRP vendor price guides (GTO FRP 2025 guide; Income Pultrusion guide, undated)](https://incomepultrusion.com/frp-grating-price-guide/) (accessed Oct 15, 2026)

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Fiberglass (FRP) grating made by NANTONG STRONGRATE CO.,LTD in Nantong, China. Products ship from China. Made in Nantong, China · Ships from China · HTS 3925.90.