Structural Steel Lead Times: Why Owners Must Challenge Their Engineers

Structural steel has always been a long lead item, but in the US it is now a constrained commodity, much like transformers and switchgear. Tariffs and import restrictions have pushed almost every project to compete for the same limited domestic mill capacity, at the same time as an AI-driven construction boom has lifted demand.

For megaprojects, the question used to be if owners should buy steel as a long lead item before the EPC, EPCM or CM contractor was appointed. Now the question is not if, but how to balance ordering early enough to avoid a schedule impact against the risk of ordering the wrong types and quantities of steel.

This article explains how steel is bought, how the market has shifted, and why owners need to push their engineers to define structural steel packages far earlier than the traditional design sequence would.

How Structural Steel Is Ordered

Structural steel (the beams, columns and braces that form a building's frame) starts at a steel mill, where it is rolled in scheduled production runs. Mills only roll each product size at set times, so the buyer is really booking a slot in the mill's calendar. Steel then goes to a fabricator, who cuts, drills and welds it into pieces ready to be erected on site.

Megaprojects usually take one of two routes to procure steel:

• Through a fabricator (the common route). The project books capacity with a fabricator, and the fabricator orders from the mill. Mills prefer this because fabricators usually have better-defined quantities and requirements, which makes the mill's dealings with its customers simpler.
• Directly from the mill. The project books mill runs itself and then passes the steel to a fabricator. The attraction is twofold: slots can be secured well before the design is mature enough to give accurate quantities, and the project avoids some of the fabricator's mark-up.

A third source, stockists (also called service centers), holds inventory from many mills and sells steel off the shelf. They are useful for small or urgent quantities but cannot supply the tonnages a megaproject needs. For projects of that scale the real choice is only between procuring through the fabricator or directly from the mill.

The risk with the direct route is the quantity itself. An early order is only as good as the preliminary design behind it. If sizes, grades or tonnages change later, the project is left with the wrong steel, or has to reorder at the back of a much longer queue.

Who Makes Structural Steel, and How Much

Three companies are the main US producers of wide-flange beams, and together they shipped about 6.1 million tonnes of structural steel in 2025. Gerdau shipped 2.59 million tonnes of shapes in North America (including its Canadian mills), Nucor shipped 2.11 million tonnes, and Steel Dynamics shipped 1.44 million tonnes (once approximately 235,000 tonnes of rail are excluded).

Imports topped this up. In 2025 the US imported up to an estimated 2.7 million tonnes of structural steel products, about 31% of total supply. That comprised 743,000 tonnes of heavy structural shapes, 1.35 million tonnes of plate and 82,000 tonnes of steel piling, plus an estimated 530,000 tonnes of fabricated beams. Plate is used well beyond structural steel; excluding it, imports were about 1.35 million tonnes — approximately 18% of supply.

Imports now face higher tariffs, and the rate depends on the type of product and country of origin — typically between 25% and 50%. Projects seeking to avoid these tariffs are turning to US domestic mills, and mills such as Steel Dynamics are already reporting longer backlogs and lead times as a result.

According to GPS estimates using multiple sources, US domestic production increased by approximately 6% in the first half of 2026 compared to a year earlier. This is unlikely to be enough to cover the additional demand driven by the AI construction boom and by projects seeking to avoid import tariffs. The race to secure domestic production capacity is on — and those who can define their requirements early and book mill slots months or years in advance will be the winners.

Why Steel Is Harder to Buy Early Than Electrical Equipment

Some may draw parallels between steel and electrical equipment, but these are fundamentally different commodities that depend on different design data. Transformers and switchgear are also scarce, but they can be reserved early: key decisions such as loads and performance ratings can be made with confidence long before the design is complete. A project can book a slot for a transformer of a given rating and refine the design later.

Structural steel does not work that way. The types, sizes and quantities of beams, columns and braces only emerge as the design progresses, because they depend on the layout, the loads and the equipment each building must carry. Until then, an order is a guess.

On the face of it there are two options: book capacity early and be confident that quantities and profiles are right, or accept delays. In practice there is only one, because construction is a schedule-driven industry. For all its cost consciousness, the industry will not accept late delivery when a megaproject's revenue or strategic value depends on a date.

What Owners Should Challenge Their Engineers to Do

This is a challenge owners need to put to their engineering firms. The default design sequence optimises for the lowest steel tonnage and the most complete information — the opposite of what a constrained market needs. Four challenges stand out.

1. Measure design maturity locally, not just overall. A project reported as 30% designed may have some areas at 90% and others at 0%. Ask engineers to track progress at asset level and also by building and area. Once the areas that drive structural steel are visible, they can be advanced deliberately and reach sufficient maturity early.
2. Treat structural sizing as critical path design. Owners already push engineers to size and define electrical systems early. The same discipline should apply to structures. Identify the areas with the greatest influence on steel packages and move them ahead of everything else.
3. Do not optimise; oversize. For electrical loads, engineers set healthy margins to allow for later growth. Owners should ask for a similar approach to steel: either oversize the structure, or freeze the design early enough to place orders. A little extra steel costs far less than months of delay, and a lean design that is not ready on time delivers no saving.
4. Design around your steel orders. Once the critical packages are ordered, less critical areas can be designed around the steel already booked. This limits reorders, keeps mill orders simple, and avoids joining the back of the queue again for each change.

These are starting points. Engineers will have other ideas that fit their project's engineering, schedule and supply chain circumstances, and owners should invite them. The test is whether the proposal gets steel on order earlier without relying on the traditional design sequence.

The Risk of Changing the Sequence

Changing the design sequence is not risk-free. Freezing structures early means committing before other disciplines have finished, and a late change to equipment loads, layouts or process requirements can invalidate steel that is already on order. Oversizing adds cost and weight, and can ripple into foundations.

Engineering firms therefore need a robust way to identify, manage and mitigate the risks of adapting the design process to market conditions. That means agreeing which loads and layouts are frozen, who owns changes to them, how much margin is carried and how it is released, and what happens to steel that proves surplus. Owners should ask to see this risk plan alongside the schedule — not after the first order is placed.