Technical Guide · Load Tables
Two Loads, One Limit
A load/span table is not a single number. It is a matrix: rows are grating types/thicknesses, columns are spans, and the cell value is the load the panel will carry at a chosen deflection limit. Three things decide the number you read:
- Uniform load (kN/m² or psf): load spread over the whole panel — pedestrians, equipment decks. Check the uniform-load table.
- Concentrated load (kN or lb): a foot, wheel or pump base on a small patch — check the concentrated-load table separately; it often governs.
- Deflection limit: the same panel carries less load at L/200 than at L/100. Always read the table for YOUR chosen limit.
Indicative Molded Example
Maximum uniform load (kN/m²) at the stated clear span and deflection limit. Values indicative; use ZeAllgrate tables for final design.
| Panel / Thickness | Span 0.9 m @ L/200 | Span 1.2 m @ L/200 | Span 1.5 m @ L/200 | Span 1.2 m @ L/150 |
|---|---|---|---|---|
| Molded 25 mm | ~5.0 | ~2.4 | ~1.4 | ~3.2 |
| Molded 30 mm | ~7.0 | ~3.6 | ~2.1 | ~4.8 |
| Molded 38 mm | ~10.5 | ~5.5 | ~3.3 | ~7.3 |
| Molded 50 mm | ~16.0 | ~9.0 | ~5.5 | ~12.0 |
| Pultruded I-60 | ~12.0 | ~6.5 | ~4.0 | ~8.8 |
Indicative values from industry load-span tables. The same panel carries more load at a longer allowable deflection (L/150 > L/200). Read the row for your thickness and the column for your span AND deflection limit.
Choose a Panel for a 1.2 m Walkway, 5 kN/m², L/200
Step 1 — find the column: clear span 1.2 m, deflection limit L/200 → read the "1.2 m @ L/200" column.
Step 2 Compare required load 5 kN/m² against each row in that column:
25 mm → 2.4 (< 5, fails)
30 mm → 3.6 (< 5, fails)
38 mm → 5.5 (> 5, passes) ← select
50 mm → 9.0 (over-specified, heavier/costlier)
Step 3 Check concentrated load too:
If a 7.3 kN foot load applies, read the concentrated-load
table for 38 mm at 1.2 m; select the next thickness if it fails.
Step 4 Confirm deflection:
38 mm at 1.2 m / 5 kN/m² ≈ 7.5 mm vs. L/200 = 6 mm →
L/200 requires the next size (50 mm). For L/150, 38 mm passes.Result: at L/150, a 38 mm molded panel works; at the stricter L/200, upsizing to 50 mm is required. This is why the deflection limit, not just the span, decides the row.
Common Mistakes
| Mistake | Consequence | Fix |
|---|---|---|
| Reading the L/100 value for an L/200 job | Panel deflects too much / feels bouncy | Always read the column for YOUR deflection limit |
| Ignoring concentrated load | A foot/wheel punches through the bar | Check the concentrated table separately |
| Pultruded bars parallel to span | Panel carries load on the weak axis | Orient bars across the short span |
| Interpolating between thicknesses | Unconservative, uncertified value | Use the next-larger certified row |
| Using a metric table at imperial span | Span mismatch, wrong load | Keep units consistent |
A 7.3 kN Foot on a 1.2 m Span
Equipment feet, wheels and drum bases are point loads; check the concentrated-load table separately from the uniform table.
Given: a 7.3 kN pump foot over a 100 x 100 mm patch on a 38 mm molded panel at 1.2 m span. Step 1 Find the concentrated-load row for 38 mm at 1.2 m. Step 2 Compare 7.3 kN to the table value (indicative ~4-6 kN for 38 mm). Step 3 If below, OK; if above, upsize to 50 mm or add a local pad under the foot. Step 4 Confirm the patch does not sit over a cut-out or unsupported edge.
Concentrated loads are where uniform-load tables mislead. A panel that passes 5 kN/m2 uniformly can still fail a single foot. Always check the concentrated row for any equipment, drum or wheel.
Keep kN, mm and psf Straight
Mixed units are a quiet source of error. Manufacturer tables may be published in metric (kN/m2, mm) or imperial (psf, inch). 5 kN/m2 is roughly 105 psf; a 1.2 m span is about 47 inches. Convert before you read the table, not after. Also note whether a table lists "maximum recommended" load (with the safety factor already applied) or "ultimate" load (failure load). ZeAllgrate tables quote recommended working load at a stated deflection limit, so you do not need to apply another factor. Finally, confirm whether the span quoted is clear span or centre-to-centre of support; they differ by the support width and shift the selected thickness.
References
- Industry load-span tables (manufacturer data) — uniform and concentrated load data. Manufacturer technical data available upon request.
- Industry molded grating engineering guide (manufacturer PDF) — deflection limits and safety factors. Manufacturer technical data available upon request.
- ZeAllgrate — Guidelines for the Engineer/Designer (ACMA) — load-table usage. ZeAllgrate.
- OSHA 29 CFR 1910.23; ASCE/SEI 7 live loads.
Worked Example: Reading Your Own Deck
Take a 38 mm molded panel on a 600 mm clear span with a required deflection limit of L/200. The table row for 38 mm molded at 600 mm span shows, say, a uniform capacity of 15 kN/m² at L/200 — meaning the panel satisfies a 5 kN/m² pedestrian load with a large margin, and would also carry typical light equipment deck loads. Repeat the read for the concentrated case: a 1.5 kN point load at the same span at L/200 governs the panel size more than the uniform case in many decks — which is why the tables are read in both columns before finalising a section.
Deflection Limits and Codes
- L/200 — the common process-plant default for walkways; comfortable underfoot and conservative for equipment.
- L/150 — accepted in many industrial platforms where some movement is tolerable.
- L/100 — maximum permitted in most codes; used where the walkway is not underfoot-sensitive.
- Special limits — vibration-sensitive areas (some cleanrooms, inspection platforms) may specify L/240 or tighter.
Your project code may state the limit directly; where it does not, L/200 is the safe default for walkways and L/150 for infrequently walked platforms.
Common Reading Mistakes
- Reading the uniform column for a concentrated load — they are separate tables and the concentrated case often governs.
- Using the nominal span instead of the clear span between supports.
- Ignoring the deflection limit and reading the highest number in the cell range.
- Applying a pultruded table value to a molded panel (or vice versa) — the constructions differ by roughly a factor of two in stiffness.
- Forgetting the safety factor applied by the supplier — confirm whether table values are ultimate or working loads.
- Reading the uniform column for a concentrated load — they are separate tables and the concentrated case often governs.
- Using the nominal span instead of the clear span between supports.
- Ignoring the deflection limit and reading the highest number in the cell range.
- Applying a pultruded table value to a molded panel (or vice versa) — the constructions differ by roughly a factor of two in stiffness.
- Forgetting the safety factor applied by the supplier — confirm whether table values are ultimate or working loads.
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