When choosing a structural steel subcontractor, check four things above all: BS EN 1090-1 certification at the right execution class, relevant commercial experience, the capacity to hit your programme, and whether they can take detailing, fabrication and erection as one accountable package.
Certification and execution class
This is the non-negotiable. A structural steel subcontractor must hold BS EN 1090-1 certification with factory production control, and be able to fabricate at the execution class your project needs. Confirm their certificate covers the execution class your project needs. Their steelwork should carry CE or UKCA marking.
Relevant experience and capacity
Residential and commercial steel are not the same discipline. Look for experience in your sector and at your scale, and ask plainly about capacity: can they take your tonnage and hit your programme, or are they already committed? A capable fabricator who can't start for months is the wrong fabricator for a live job.
Detailing and erection capability
Find out what they do in-house and what they sublet. A subcontractor who handles detailing, fabrication and erection under one roof gives you a single point of accountability from drawings to erected frame, rather than a chain of suppliers pointing at each other when something slips.
Health, safety and track record
Steel erection is high-risk work. Check their safety record and any SSIP-recognised accreditation (such as CHAS), ask for references on comparable projects, and confirm they work to documented method statements and lift plans. A strong track record on similar jobs tells you more than any brochure.
The checklist
- BS EN 1090-1 certified with FPC, at the execution class you need
- CE or UKCA marked steelwork
- Relevant commercial-sector experience at your scale
- Genuine capacity against your programme
- Detailing, fabrication and erection capability and how much is in-house
- SSIP-recognised safety accreditation and method-statement discipline
- References on comparable projects
If you're shortlisting for a live package, send us the drawings and we'll show you exactly where we sit against this list.
Common questions
- What certification should a steel subcontractor have?
- BS EN 1090-1 certification with factory production control, at the execution class your project requires (EXC2 for most general building work), and CE or UKCA marking on the steelwork. This is the baseline for any commercial steel package.
- Should detailing, fabrication and erection be one subcontractor?
- It's usually the stronger arrangement. One accountable team across detailing, fabrication and erection keeps the package on a single programme and removes the gaps that appear when separate suppliers hand work between each other.
- What questions should I ask a steel subcontractor?
- Ask about their execution-class capability, current capacity against your programme, what they do in-house versus sublet, their safety accreditation and method-statement discipline, and references on comparable projects.