Direct Answer
Structural steel is priced by the ton, with hot-rolled sections (W-shapes, channels, angles) priced per the service center's price list plus freight, and with market fluctuations tied to global steel supply, scrap prices, and mill production costs. Plate and bar are separately priced, often at a premium over structural shapes. Fabricated steel (material plus labor) is priced per ton of finished structure.
Full Explanation
The steel price chain: steel mills set pricing based on raw material (scrap or iron ore) and rolling costs. Service centers buy from mills and mark up based on inventory, processing, and delivery. Fabricators buy from service centers (or directly from mills on large orders) and add fabrication labor, overhead, and profit. The spot market price for W-shapes has historically ranged from $500–$1,200/ton; market spikes (as seen in 2021) can exceed $2,000/ton temporarily. For bids with long lead times, consider using index-based pricing clauses that allow material cost adjustment if prices move more than a defined threshold.
What This Means for Your Shop
Lock in material pricing as close to contract signing as possible. If there's a significant gap between bid date and purchase date (>60 days), your bid-to-buy risk is real. Escalation clauses in your subcontract protect you from absorbing mill price increases on multi-year projects.
Common Mistakes
Bidding a 12-month project at current steel prices without an escalation provision, then watching prices increase 20% between bid and purchase. This is a margin-eliminating event.
Recommended Process
For projects longer than 6 months, include a steel price escalation clause tied to the Metals Service Center Institute (MSCI) or CRU index. Request from the owner that structural steel be owner-furnished (they buy the steel, you fabricate) on large, long-duration projects.