AISC vs EN 1090-2: Which Certification Your Project Actually Needs

The two certificates answer different questions

Buyers routinely treat “AISC certified” and “CE marked to EN 1090” as interchangeable proof of a good fabricator. They are not. One is a European legal requirement attached to the product you import; the other is a North American audit of how a shop runs. A supplier can hold both, either, or neither and still weld competently — what changes is what you can legally do with the steel once it lands, and what a third-party inspector will accept.

The practical question is not “which is better” but “which one does my project actually require, and does the certificate in front of me cover the work I am buying”.

What CE marking under EN 1090-1 actually certifies

Under the EU Construction Products Regulation (Regulation No 305/2011), structural steel components placed on the European market must carry CE marking supported by a Declaration of Performance. The certificate behind that marking is a Factory Production Control certificate — it attests that the manufacturing plant’s internal control system was assessed by a notified body and found conforming to Annex ZA of EN 1090-1.

Read that carefully: it certifies the factory’s control system, under system 2+, not any individual beam. It says the shop is capable of consistently producing to a declared performance. It does not by itself say the members you receive were fabricated correctly — that is what the Declaration of Performance, the inspection records and the Manufacturing Data Report are for.

Our own certificate is a useful worked example. Certificate 2787-CPR-01627 covers steel structures and components to EN 1090-2, execution class EXC2, declaration methods 3a) and 3b) per table A1 of EN 1090-1:2009+A1:2011, under system 2+. The assessed manufacturing processes are listed explicitly: cutting, drilling, welding, NDT, assembly and corrosion protection. It was first issued on 06.02.2026 and runs to 05.02.2029.

Every one of those fields matters to you. The certificate number identifies the document; the four-digit prefix identifies the notified body; the process list tells you what the audit actually covered; the execution class tells you the ceiling of what the shop is certified to fabricate.

How your execution class is decided — and why EXC2 covers most industrial buildings

Execution class is one of the most misunderstood items in a steel tender. Buyers ask suppliers “are you EXC3 certified?” as though it were a rank. It is not a rank, and it is not the fabricator’s decision.

EXC is assigned by the designer, derived from three inputs set out in EN 1990 Annex B and EN 1090-2 Annex B: consequence class (CC1–CC3, how bad the failure is), service category (SC1 predominantly static, SC2 fatigue or seismic), and production category (PC1 non-welded or low-strength, PC2 welded high-strength or complex). Those combine into EXC1 through EXC4.

In practice, single-storey portal frame workshops, warehouses, logistics sheds and the great majority of light-to-medium industrial buildings land in EXC2. EXC3 appears when the structure is in a higher consequence class or carries fatigue loading — stadium roofs, long-span public assembly structures, crane runway girders under heavy cyclic duty, bridges. EXC4 is reserved for exceptional-consequence structures and is rare in commercial building work.

The correct sequence is: your engineer states the required EXC in the design documents, and you then confirm the fabricator’s certificate covers at least that class. Asking a shop to self-declare a class without a design basis inverts the process, and a fabricator who volunteers “we can do EXC3” without asking about your consequence class is telling you something about their engineering discipline.

What AISC certification covers that CE marking does not

AISC certification is a different instrument entirely. It audits a fabrication shop against AISC’s Certification Standard for Steel Building Structures — management responsibility, document control, personnel qualification, calibration, material traceability, welding procedure control, inspection. It is a quality-management audit conducted on the shop floor.

It carries no legal standing in the EU: an AISC certificate does not permit CE marking, and no volume of AISC audits substitutes for a notified body assessment under the CPR. Conversely, a specification written to AISC 360 with AISC certification required cannot be satisfied by an EN 1090 certificate alone.

Where both matter is on projects with mixed design basis — a US or Gulf engineering firm designing to AISC 360 for a site inside the EU, or a European EPC exporting a plant to a jurisdiction that references US codes. Holding both means the shop has been examined twice, under two different philosophies, and can produce documentation in the format each inspector expects.

How to verify a supplier’s certificate in ten minutes

Certificates circulate as JPEGs and are trivially easy to misrepresent. Four checks catch nearly everything:

• Match the legal entity and the plant address. Group certificates are common. The certificate must name the factory that will cut your steel, at the address where it will be cut — not a sister company, not a head office.
• Check the execution class against your design requirement. A valid EXC2 certificate is worthless to you if your engineer specified EXC3.
• Check the validity dates and ask for the Document of validity. An EN 1090-1 FPC certificate is issued with a separate validity document as an inseparable part; a certificate presented without it is incomplete, and surveillance audits under system 2+ can suspend it between issue and expiry.
• Check the process scope and the welding annex. The certificate lists which processes were assessed. If welding is central to your scope, the welding annex should reference the welding coordination personnel and the standards the shop is qualified under.

Two of these you can run against the scanned certificate itself. The other two need a direct answer from the supplier — and how quickly a supplier answers is information in itself.

What a compliant document package looks like at delivery

Certification is the start of the paper trail, not the end. For a CE-marked structural steel consignment, expect the Declaration of Performance referencing the harmonised standard, the FPC certificate with its validity document, mill test certificates for every heat used, welding procedure specifications with their qualification records, welder or operator qualification certificates, NDT reports with the technician’s qualification level, and coating thickness measurement records against the specified system.

Approval delays on imported steel are far more often documentary than technical. If your inspector receives that package complete on the first visit, the release conversation is short. If it arrives in pieces over three weeks, the structure sits in the yard while the paperwork catches up — which is the same cost as a fabrication delay, dressed differently.

For how these requirements feed into the price you are quoted, see our breakdown of what actually drives the cost of a portal frame workshop.