NMFC Class 50 — Building Materials
Steel products are extremely dense and almost always qualify for freight class 50, the lowest (cheapest) class.
Typical class: 50 · Density: 50–200 lbs/cu ft
Shipment Dimensions (inches)
| Class | Density (lbs/cu ft) | Description |
|---|---|---|
| 50 | 50+ | Heaviest, most dense freight |
| 55 | 35–50 | Very dense freight |
| 60 | 30–35 | Dense freight |
| 65 | 22.5–30 | Moderately dense |
| 70 | 15–22.5 | Average density |
| 77.5 | 13.5–15 | Slightly below average |
| 85 | 12–13.5 | Below average density |
| 92.5 | 10.5–12 | Light freight |
| 100 | 9–10.5 | Light freight |
| 110 | 8–9 | Light, bulky freight |
| 125 | 7–8 | Bulky freight |
| 150 | 6–7 | Very bulky freight |
| 175 | 5–6 | Very light, bulky |
| 200 | 4–5 | Extremely light |
| 250 | 3–4 | Extremely light, high value |
| 300 | 2–3 | Low density, high handling |
| 400 | 1–2 | Very low density |
| 500 | 0–1 | Lowest density, highest cost |
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NMFC Class 50 — packaging, handling, and freight class details
Steel and metal products are the densest common freight commodity and consistently qualify for Class 50 — the lowest available freight class. Steel service centers, mills like Nucor and Commercial Metals Company, and steel distributors ship structural steel, flat-rolled coil, sheet metal, reinforcing bar, tube and pipe, and miscellaneous steel mill products daily through every major industrial corridor in the country. The construction and manufacturing sectors drive steel demand, making steel freight volume a reliable economic indicator.
The density story with steel is extreme. Structural steel channels weighing 50–80 lbs per foot, steel coil weighing 20,000–40,000 lbs per coil, reinforcing bar bundles — all these materials exceed 100 lbs/cuft at minimum. Class 50 is always appropriate. The consequence is very low per-hundredweight rates, but because payloads are weight-limited rather than cube-limited, carriers still earn well on heavy steel loads.
Flatbed is the only practical equipment for most steel freight. Long structural shapes, wide sheet metal bundles, and heavy coils cannot fit in dry van trailers and require the side-loading access of a flatbed or step-deck. Steel coil requires specialized coil racks or cradles on the trailer to prevent rolling. Tie-down requirements for steel are strict — FMCSA cargo securement rules specify tie-down multipliers based on piece weight, and steel loads require more tie-downs per ton than lighter freight.
Rust and corrosion protection matters for steel deliveries to job sites where the material may sit outdoors. Some steel is shipped bare and expected to develop a protective oxide layer; other steel (galvanized, coated, or finished) must be protected with appropriate wrapping. When accepting coated or painted steel, check for existing surface damage before signing the BOL. Rate context: steel freight pays at Class 50 rates — low per hundredweight, but heavy payloads make the math work. Consistent flatbed steel lanes are bread-and-butter work for many owner-operators.
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