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Key Takeaways
- Metal building contractors design and build pre-engineered metal building systems, and they're ranked not by revenue but by tonnage of steel erected.
- Span Construction & Engineering is the largest metal building contractor in the US for the 30th-plus year running, at 39,745 tons in 2025, up 18% year over year.
- The fastest climbers in 2026 were BARNES Buildings (up ~308% to 3,269 tons) and Freeman Building Systems (up ~213% to 2,386 tons).
- Metal building systems construction is a distinct trade from HVAC sheet metal and structural steel, though it overlaps with both.
- Data centers are an emerging driver of demand for the trade. Butler Manufacturing alone has built more than 2 million square feet of hyperscale data center space using its pre-engineered systems.
Pre-engineered metal building systems go up fast and cheap, which is why they dominate warehouses, distribution centers, data centers, manufacturing plants, and big-box retail. The trade is growing, though the pace looks different depending on which numbers you check. Metal Construction News’s (MCN) 2026 survey shows average contractor tonnage down 10% year over year (2,394 to 2,151 tons) even as square footage rose 7.3%, and the 10 largest contractors and erectors now hold just 49% of the top 100's tonnage, the most fragmented the industry has been in 15 years.
That said, the broader pre-engineered building market grew from about $22 billion to $48 billion in 2026, and data centers are a growing part of that demand. US data center construction spending jumped 138.6% year over year through November 2025, and manufacturers like Butler now run dedicated data center building programs.
The contractors that build these systems are ranked a little differently than most trades: by tonnage of metal building systems erected, not by revenue. MCN publishes two industry benchmark lists (Top Contractors and Top Erectors) every May, and comparing its 2026 ranking (2025 tonnage) to the 2025 ranking (2024 tonnage) shows who's climbing.
Metal Building Contractors vs. Metal Building Erectors
But first—what’s the difference between metal building contractors and metal building erectors? Contractors are not manufacturing the steel. Manufacturing companies fabricate the panels, frames, and trim for a pre-fab metal building. A contractor is typically an authorized builder or dealer for one of those manufacturers; it sells and design-builds the project, then usually self-performs the erection.
Erectors are hired to do one job: put the steel up. Some also furnish buildings and could land on the contractor side of a different project, but if a firm is contracted only to erect, MCN counts it as a contractor rather than splitting the numbers. That's why Steelworx shows up as a top contractor in 2025 and a top erector in 2026: same company, different contract role on different jobs.
Pre-fab metal building erection is also a narrower trade than general steel erection. A structural steel erector assembles custom, project-engineered steel, usually with heavier members, field welding, and complex connections for things like high-rises or industrial plants. A metal building erector bolts together a pre-engineered kit, tapered rigid frames, purlins, girts, and panels, all fabricated to one manufacturer's standard system and built to go up fast. It's quicker and far less customizable. That’s why the builds are typically big-box-style builds.
To start, here’s the 2026 contractor ranking (based on 2025 tonnage), alongside last year’s list to show which contractors are climbing the ranks.
Top Metal Building Contractors by Tonnage (2026)
Source: Metal Construction News, 2026 Top Metal Building Contractors (2025 tonnage). "New" means the firm wasn't in the prior year's ranked rows.
Biggest Movers From 2025 to 2026
Because a single large warehouse or distribution center build can cause a dramatic uptick in tonnage, a mid-size contractor can jump several spots in ranking within a year. Consider that when reviewing the list’s climbers and decliners.
Climbers
- BARNES Buildings & Management Group more than quadrupled its tonnage, from 801 to 3,269 tons (up roughly 308%)—the biggest jump in the top 25.
- Freeman Building Systems tripled its tonnage, from 763 to 2,386 tons (~+213%).
- Yonkers Industries went from 853 to 2,597 tons (~+205%).
- Veneklasen Construction rose from 1,050 to 2,827 tons (~+169%).
- WENCO Construction doubled, from 1,619 to 3,336 tons (~+106%).
- Span grew a modest 18%, from 33,605 to 39,745 tons.
- Lemartec climbed from 8th (5,925 tons) to 5th (8,550 tons), a ~44% increase.
Decliners
- Dunn Building Company fell hard, from 6,340 to 2,054 tons (down ~68%), dropping from the top 10.
- Sure Steel continues to hold the #2 spot, but slipped 21%, from 27,016 to 21,307 tons.
The Largest Metal Building Contractors
1. Span Construction & Engineering
HQ: Madera, CA | 2025 Tonnage: 39,745
Span, an employee-owned design-build contractor, has topped this list for more than three decades. During that time, the company has erected over 200 million square feet of metal buildings, including more than 100 million square feet for Costco, and works closely with Butler Manufacturing. Its total tonnage output in 2025 (39,745 tons) is nearly double the second-ranked firm on the list.
2. Sure Steel
HQ: South Weber, UT | 2025 Tonnage: 21,307
Sure Steel is a national specialty erector spanning metal building systems, structural steel, precast, and insulated metal panels. An AISC Advanced Certified Steel Erector with $500 million in single-project bonding capacity, it works with American Buildings, Ceco, and Varco Pruden, among others.
3. Image Building Systems
HQ: Tempe, AZ | 2025 Tonnage: 9,870
Image Building Systems designs, fabricates, and installs custom-engineered metal, steel, and fabric buildings across the Southwest. It was the first metal building assembler in Arizona and Nevada to earn IAS AC478 accreditation and has erected more than 9.7 million square feet in Arizona alone.
4. Keller, Inc.
HQ: Kaukauna, WI | 2025 Tonnage: 8,687
Founded in 1960 and 100% employee-owned, Keller is a single-source commercial design-build firm with in-house planners, architects, and builders across Wisconsin. The company is also an authorized builder for American Buildings, a Nucor-owned manufacturer of pre-engineered metal building systems.
5. Lemartec
HQ: Miami, FL | 2025 Tonnage: 8,550
Lemartec, owned by MasTec, provides EPC (engineering, procurement, and construction) and design-build services across the industrial, aviation, and energy markets. An authorized Varco Pruden builder, the company climbed from 8th to 5th, increasing its tonnage by 44% within the year.
Top Metal Building Erectors by Tonnage (2026)
Metal Construction News ranks erectors separately from contractors. Erectors specialize in putting up (erecting) the steel, often on behalf of other firms. Here are the top 15 in tonnage for 2025.
Source: Metal Construction News, 2026 Top Metal Building Erectors (2025 tonnage). Top 15 of 21.
What Metal Building Contractors Can Learn from the Leaders
The firms at the top of these lists share a few things: They partner closely with a manufacturer; they self-perform erection to control schedule; and they chase the large, repeatable projects—like warehouses, distribution centers, data centers, and factories—where tonnage adds up fast.
They also run tight back offices. Metal building work moves quickly and bills on progress, so getting pay applications out fast and collecting on time is what keeps cash flowing between big jobs. Metal building and steel contractors use Siteline's construction billing software to bill faster, protect cash flow, and pursue the GCs that pay on time. Schedule a demo to see how it would benefit your company.
Frequently Asked Questions
How is a metal building contractor different from a steel contractor?
Metal building contractors furnish and erect pre-engineered steel building systems. They buy factory-built kits of frames, panels, and trim from manufacturers like Butler or Varco Pruden and assemble them on-site. A structural steel contractor instead erects custom, project-engineered steel that's cut and often welded to spec—a slower, more customizable process.
Who is the largest metal building contractor in the US?
Span Construction & Engineering erected 39,745 tons in 2025, nearly double the next firm in the list of top metal building contractors by tonnage in the US.
How are metal building contractors ranked?
Per Metal Construction News, metal building contractors are ranked by tonnage of metal building systems erected, not revenue.
Which metal building contractors grew the most?
BARNES Buildings (~+308% in tonnage) and Freeman Building Systems (~+213%) are the two metal building contractors that saw the largest growth between 2024 and 2025.
What are affiliated manufacturers?
Affiliated manufacturers are the suppliers of the pre-engineered building system. Common companies include Butler, Varco Pruden, Nucor, or Ceco.
AIA®, G702®, and G703® are registered trademarks owned by The American Institute of Architects and ACD Operations, LLC. Siteline is not affiliated with The American Institute of Architects or ACD Operations, LLC. Users who wish to use Siteline’s software to assist in filling out AIA® forms must have or secure the AIA® forms. Siteline does not and will not provide users with the forms.
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