Metal or Fiberglass Grating: How to Actually Choose (A Buyer's Guide from a Non-Engineer)

I'm not an engineer. I'm the person engineers send to "figure out what grating we need" — which is a polite way of saying it's my problem now.

I manage purchasing for a mid-sized manufacturing company. Roughly $200k in annual orders across about 15 vendors. Grating is one of those recurring items nobody thinks about until it becomes a problem. After five years of ordering metal products, I've learned there's no universal answer. The right grating depends entirely on your situation.

Here's how I break it down.

Three Scenarios, Three Answers

Most grating decisions fall into one of three scenarios:

1. Corrosive or chemical exposure → fiberglass grating
2. Heavy loads and forklift traffic → welded steel grating
3. Light duty, guards, or aesthetics → perforated metal or wire mesh

Let me walk through each one, including the things I wish someone had told me before I placed my first order.

Scenario A: Chemicals or Salt? Go Fiberglass

If your grating lives near chemicals, salt water, or a washdown station that never completely dries, skip steel entirely. Steel will eventually rust, and painted steel is just steel with a delayed reaction.

We learned this the hard way in 2021. I ordered steel grating for a washdown area at our plant. It looked fine for about eight months. Then rust started climbing up from the cut edges. By month fourteen, we were replacing sections. Total cost—materials plus labor plus the production time we lost—came out to more than fiberglass would've cost us upfront. That's a mistake I haven't repeated.

What to look for in fiberglass grating

McNichols has a serious fiberglass selection, and their mcnichols grating catalog PDF is the best place to start. It shows all the product lines with load tables side by side, which is rare. Most suppliers make you dig through separate pages for each product.

The McNichols Eco Mesh line is the one I'd point you to first. Eco Mesh is a molded fiberglass product that's lighter than pultruded fiberglass, and the construction gives it a nice balance of strength and open area. We've used it on two projects: a catwalk over a chemical sump area and a platform in our washdown bay. Both have held up well with zero signs of corrosion, and that includes constant overspray from the washdown guns.

The smaller open area of Eco Mesh is worth noting. It's about 40% open, compared to the 60% you get from some pultruded gratings. That means more chip protection if you're using it as a walkway, but it also means more dust can collect on top. For most indoor applications that's fine. For a cleanroom or food processing area, talk to a sanitary design consultant first.

Full honesty: I don't understand the fiberglass chemical compatibility charts as well as I'd like. I can read them, but the difference between "suitable for continuous immersion" and "splash only" is a judgment call I always verify with a supplier engineer. My best guess is the technical difference comes down to resin systems, but I've never fully kept it straight. If someone has a clear explanation, I'd genuinely like to hear it.

Scenario B: Forklifts and Heavy Loads? Steel, Galvanized

For loading docks, manufacturing floors, and anywhere heavy equipment regularly rolls across, welded steel grating is the answer. There's not much debate on this one.

Our dock area is where this played out. The original spec—written before my time and before I knew better—was steel grating with relatively wide bearing bar spacing. It flexed noticeably every time the forklift crossed it. The gap was big enough that on one delivery, a pallet jack wheel caught between two bars and the driver had a near-miss.

Replacing it was my first major grating purchase. I had quotes from three suppliers, and the numbers said go with the cheapest one. My gut said the narrower spacing on the McNichols product was worth the extra cost. I went with the numbers. Within six months, I knew I'd made the wrong call.

We ended up replacing that first replacement with McNichols welded steel grating: 1-3/16 inch bearing bar spacing, 2-1/4 inch depth, galvanized. That order went in back in March 2024, and it's been exactly what I should have bought the first time. No flex. No rust. No drama.

If you're in this scenario, do yourself two favors:

1. Pick the full bearing bar, not the light version. The price difference is smaller than you think, and the deflection difference is huge.
2. Get galvanized, not painted. Painted grating looks fine for about a year, then it doesn't. Galvanized costs more but it's the buy-once answer.

One more thing about McNichols as a supplier. On a different project, their engineer told me, "You don't need the heavier bearing bar for this application—it's overkill." That saved us roughly 15% on material, and it cost them margin on that transaction. I've trusted their quotes ever since.

Scenario C: Light Duty, Guards, or Visual Appeal? Perforated or Mesh

Here's the one that surprises people: not every "grating" need actually requires a grating.

If you're building a maintenance walkway that gets used twice a month, a machine guard, or a decorative screen, you probably don't need structural grating. Perforated metal or wire mesh is cheaper, lighter, and looks dramatically better in spaces that humans actually see.

We used McNichols' perforated metal panels for the mezzanine rail infill in our office-adjacent area. The engineers originally specified flat bar grating. I pushed back, mostly because I knew what flat bar grating looks like, and it's not what you want in a building where you host client tours.

The perforated panels with 1/4-inch round holes look like a deliberate architectural choice. Same safety function, at roughly 40% of the grating cost. That's based on quotes I received in March 2024—metal prices move around, so I'd verify current pricing through the McNichols catalog.

Eco Mesh deserves another mention here. It sits in that middle zone between heavy structural grating and decorative metal. If you want drainage and safety but don't want the industrial prison-yard look, Eco Mesh is a comfortable compromise. It's also lighter to handle, so installation is faster. Our maintenance crew thanked me for that.

How to Know Which Scenario You're In

Here's a three-question check:

1. Will it touch chemicals or salt? Yes → fiberglass (Scenario A)
2. Will heavy equipment drive across it? Yes → welded steel, galvanized (Scenario B)
3. Is it primarily for access, guarding, or looks? Yes → perforated or mesh (Scenario C)

That covers roughly 90% of the decisions I deal with. The remaining 10% is hybrid cases: chemical resistance plus heavy loads, or cleanroom requirements plus structural strength. When you're in that territory, talk to an engineer or a supplier engineer (McNichols has them and they're generally straight shooters). A blog post won't save you.

Whatever you end up buying, the catalog PDF is probably the single most useful artifact before you order. It has the load tables, the span charts, and the corrosion guide all in one place. When your plant engineer asks you, "What's the safe uniform load on this?" you'll want to be able to answer that without guessing.

Guessing is exactly how I got here—and how I ended up on a first-name basis with the local steel service center. Learn from my mistakes.