Steel bid packages use three words that sound interchangeable and are not: fabricator, erector, and single-source. Which one you award shapes how many contracts you manage, where the risk sits, and how tightly your frame tracks the schedule. Here is what each role does and when each makes sense.
The three roles, defined
The clearest way to see the difference is to follow the steel from drawing to standing frame.
| Role | Where they work | What they own |
|---|---|---|
| Fabricator | The shop | Turning drawings into finished members: cut, drill, weld, coat |
| Erector | The field | Rigging, craning, setting, plumbing, and connecting steel on site |
| Single-source | Shop and field | Both halves under one contract, from shop drawings to final bolt-up |
A fabricator takes the structural engineer’s design and the detailer’s shop drawings and produces steel members: beams, columns, braces, and connections, cut to length, drilled, welded, and coated, then shipped to the site. A fabricator is measured on accuracy and on-time delivery.
An erector receives that steel and stands it. Erection is crane and rigging work: setting members, plumbing the frame, and making the field connections by bolt or weld, in a safe and engineered sequence. An erector is measured on field safety, productivity, and sequence.
A single-source subcontractor does both, with its own crews, under one contract. TMG | Tri-State Metal Group is built this way: the shop and the field are the same company, so the fabrication and erection are planned together from day one.
When each is used
- Fabricator only. You buy fabrication when erection is self-performed by your own forces or by a separate specialist you already trust, and you only need steel delivered to the site.
- Erector only. You hire erection alone when the steel is being supplied by others, for example an owner-furnished or design-build package where fabrication is already contracted.
- Single-source. You award both to one team when you want fabrication sequenced to the erection plan, one accountable party on the critical path, and no seam to manage between shop and field. This is the common choice on schedule-driven commercial work like data centers, hotels, and malls.
Why the split creates a seam
When two companies own the two halves, the gap between them becomes yours to manage. A separate fabricator ships to its own shop efficiency, not to your erection sequence, so steel can arrive in the wrong order. When a connection does not fit, the fabricator points at the erector’s layout and the erector points at the shop’s dimensions, and the RFI clock runs while you referee. Two companies also means two quality chains and two welding programs to reconcile. Because steel sits upstream of every following trade, each of those gaps multiplies on the critical path.
The single-source advantage
Single-source closes the seam by design. Because the shop and the field answer to the same team, fabrication is built around the erection plan, deliveries match the sequence, and a field change is adjusted in the shop by the same company, often the same day. One contract, one schedule, one QA/QC chain, one party accountable from the first shop drawing to the last bolt-up. For a deeper comparison of the two models on schedule and cost, see single-source vs. splitting fabrication and erection.
When splitting can still make sense
Splitting is not automatically wrong. If you self-perform erection with your own union crews, or a project’s fabrication and erection genuinely belong to different specialists, two contracts can be the right structure. The discipline is to price the coordination rather than assume it is free, and to know exactly who owns fit-up, sequence, and weld quality across the handoff.
If you want one team accountable for the whole steel package, that is what single-source means, and it is how TMG is built. Bring your drawings to a scope review and we will show you where the shop and the field line up.