Technical Guide · Terminology
Fourteen Terms Every Specifier Should Know
A quick reference to the words used across ZeAllgrate datasheets, load tables and specifications.
| Term | Plain-English Meaning |
|---|---|
| Bearing bar | The primary load-carrying bar of a pultruded panel; runs across the span. In molded panels, the deeper of the two bar directions. |
| Cross-rod / tie rod | Steel or FRP rod threaded through holes in pultruded bearing bars to tie them into a panel; distributes concentrated load across bars. |
| Mesh / grid opening | The clear opening between bars, e.g. 38 × 38 mm (1½ × 1½ in). Smaller mesh stops debris and feet; larger mesh drains faster. |
| Molded grating | Compression-molded panel with bi-directional continuous mat/roving; roughly 33% glass; equal strength in both axes. |
| Pultruded grating | Continuous pultrusion of aligned rovings into I/T bars, tied by cross-rods; ~70% glass; stiff and uni-directional. |
| Resin matrix | The polymer (polyester, vinyl ester, phenolic) that binds the glass and sets chemical, heat and fire performance. |
| C-glass / surfacing veil | A thin, resin-rich surface layer that covers the outermost glass and prevents fiber bloom under chemical attack. |
| Grit top | Embedded silica/carborundum aggregate on the walking face for wet-surface slip resistance. |
| Barcol hardness | Indentation hardness of the cured resin surface; a quick factory check of cure degree (≥ 40 polyester / ≥ 35 VE). |
| FOS / safety factor | Ratio of ultimate strength to allowable working stress; typically 4:1 molded, 5:1 pultruded, per ZeAllgrate practice. |
| Deflection limit | Maximum allowable midspan sag, e.g. L/200 = span divided by 200; serviceability criterion that usually governs FRP. |
| Clip (G-clip / wedge) | Stainless or FRP fastener that holds the panel bar to the support angle; SS304/316 in corrosive service. |
| C-veil edge banding | FRP flat bar or resin sealer applied to cut edges to restore the resin-rich barrier. |
| NPV / LCC | Net present value / lifecycle cost; the 25-year discounted comparison used to choose FRP over metal. |
Definitions aligned with ZeAllgrate Guidelines and industry manufacturer catalogs.
What You Are Actually Looking At
Molded and pultruded panels use the same vocabulary but build load differently.
Molded panel
A compression-molded grid where continuous roving and mat lay in both directions. There is no single "bearing bar"; the panel is bi-directional. Glass content is roughly 33% by weight. Choose it for moderate loads, short spans, impact and wet/corrosive duty.
Pultruded panel
A set of continuous I/T-shaped bars pulled through a die (~70% glass), tied by cross-rods. Load travels along the bars only. Choose it for long spans, heavy loads and where stiffness matters most. Orient the bars across the short span.
Resin · Glass · Surface
When you specify a panel, three things are actually being chosen.
- Resin matrix — decides chemical resistance, heat limit and fire behavior (see the resin comparison guide).
- Glass form & content — decides strength, stiffness and impact; bi-directional mat (molded) vs. aligned roving (pultruded).
- Surface finish — decides slip resistance and cleanability (concave, convex, grit, micro-mesh; see the surface guide).
What the Code Actually Says
Manufacturer part numbers pack the key selection choices into one string. A typical molded code reads THICKNESS-MESH-RESIN-SURFACE, e.g. 38-38-ISO-GRIT.
| Code Segment | Example | Meaning |
|---|---|---|
| Thickness | 38 | Panel depth in mm (25/30/38/50) |
| Mesh opening | 38 | Clear opening between bars, mm |
| Resin | ISO / VE / NVE / PH | Isophthalic / vinyl ester / novolac / phenolic |
| Surface | GRIT / CONV / CONC | Grit-top / convex / concave |
| Color | GRY / GRN / YEL | Gray / green / yellow (optional suffix) |
Read the code before you read the price: thickness sets span, resin sets chemistry, surface sets slip.
Common Language, Fewer Mistakes
Grating projects go wrong most often when two people use the same word to mean different things. A contractor who hears "38 mm panel" may assume molded 38 mm at a 38 mm mesh, while the engineer meant a pultruded 38 mm deep bar at a different spacing. A clip called "G-clip" by one supplier is a wedge by another, and "Class A" on a brochure is not the same as an E84 Class A report for the batch. Using the terms in this guide - and writing thickness, mesh, resin, surface and clip type into every drawing - removes that ambiguity before the panel is ordered. When in doubt, ask for a sample marked with the part number; the part number encodes the vocabulary.
References
- Industry molded grating engineering guide (manufacturer PDF) — terminology and panel anatomy. Manufacturer technical data available upon request.
- Industry pultruded grating metric design manual (manufacturer PDF) — bar and hardware terminology. Manufacturer technical data available upon request.
- ZeAllgrate — Guidelines for the Engineer/Designer (ACMA) — standard definitions.
Resin and Surface Terms
| Term | Plain-English Meaning |
|---|---|
| Gel coat | Thin resin-rich surface layer on molded panels; the first line of defence against chemical splash and UV. |
| Grit-top | Silica/ceramic grit bonded into the walking surface at manufacture; the highest-wet-COF finish. |
| Concave / convex surface | Molded-in texture profiles; concave cells drain, convex domes shed water and give firm footing. |
| Isophthalic / vinyl ester / phenolic | The three resin families in order of chemical resistance and cost; see the resin comparison guide. |
Load and Testing Terms
| Term | Plain-English Meaning |
|---|---|
| Uniform load | Load spread over the whole panel area (kN/m² or psf); the pedestrian/deck design load. |
| Concentrated load | Load applied to a small patch (kN or lb); a wheel, pump base or dropped load; often the governing case. |
| Clear span | The unsupported distance between bearing supports — the span the load table refers to. |
| Deflection limit | The permitted sag under load, usually stated as a fraction of span (L/200, L/150, L/100). |
| Barcol hardness | A surface hardness reading used as a cure check on production panels. |
| E84 flame spread | The ASTM E84 tunnel-test result (flame spread + smoke indices) used for fire classification. |
| COF | Coefficient of friction — the slip-resistance number for the walking surface, reported dry and wet. |
Structural Terms
Bearing bar and cross-rod describe the pultruded construction: bearing bars carry the load across the span, and cross-rods (steel or FRP) tie the bars into a panel and distribute concentrated loads. Mesh / grid opening is the clear space between bars — 38 × 38 mm standard, 25 × 100 mm and 19 mm mini-mesh variants for different drainage and foot-traffic needs. Getting these terms exact is what keeps a specification unambiguous between the engineer, the fabricator and the site crew.
Bearing bar and cross-rod describe the pultruded construction: bearing bars carry the load across the span, and cross-rods (steel or FRP) tie the bars into a panel and distribute concentrated loads. Mesh / grid opening is the clear space between bars — 38 × 38 mm standard, 25 × 100 mm and 19 mm mini-mesh variants for different drainage and foot-traffic needs. Getting these terms exact is what keeps a specification unambiguous between the engineer, the fabricator and the site crew.Confused by a Specification Term?
Email sales@izeall.com with the term or datasheet line — our engineers will explain it against your project.