On every steel project there is a procurement decision the owner either makes deliberately or makes by default: buy the steel as one integrated package, or split engineering, detailing, and fabrication across multiple contracts and let the GC coordinate. The choice changes total cost, schedule, change-order volume, and who owns the warranty when something goes wrong. Here's a frank side-by-side.
The two procurement models
Multi-vendor (the default on most public bids)
- Owner contracts a structural engineer (SER) for design
- GC tenders fabrication to multiple AISC-certified shops
- Winning fabricator subcontracts detailing
- If delegated connection design is required, fabricator hires a connection engineer
- Coatings and erection often separately tendered
- GC coordinates RFIs and change orders across all parties
Single-source (one provider, one contract)
- One firm holds structural engineering, connection design, detailing, and managed fabrication under one contract
- Fabrication runs through a vetted network of AISC-certified partner shops
- Coatings, delivery, and (optionally) erection bundled or tightly managed
- One PE/SE stamp covers structural drawings and connection design
- One warranty path; one project manager owns the schedule
Cost comparison
Treat these as planning numbers for a typical 200-ton commercial building project. Real bids will vary with location, mill pricing, and connection complexity.
Multi-vendor breakdown
- SER design fee: 1.5–2.5% of construction cost
- Fabricator bid markup (covers GC coordination risk, schedule risk, RFI cycles): 12–18%
- Detailing subcontract: $35–55/hour, 800–1,500 hours typical
- Connection design subcontract: $150–250/hour, 60–120 hours typical
- Change orders from RFI gaps: typically 3–6% of contract value
Single-source breakdown
- Engineering + detailing + connection design billed as one engineering package, no double markup
- Managed fabrication markup over partner-shop pass-through cost: 8–12%
- Change orders: typically 1–2% of contract value (RFIs resolved internally)
- Schedule recovery: 2–4 weeks on a typical project
Net delivered cost is usually within 3–7% of multi-vendor. The real savings are in schedule and change-order avoidance, not the line-item bid sheet.
Schedule comparison
Where single-source consistently wins is the front-end overlap. A single-source provider can place mill orders before the structural drawings are 100% complete because the same firm controls both — no contractual barrier between "design done" and "fabrication started." On multi-vendor projects, the fabricator can't order steel until the SER releases the drawings, the GC awards fabrication, and the fabricator's detailer completes the ABM.
| Phase | Multi-vendor | Single-source |
|---|---|---|
| Design → tender → award | 6–10 weeks | 0 (already contracted) |
| Detailing start to first submittal | 6–10 weeks | 4–7 weeks |
| SER review cycle | 10 business days × 2–3 rounds | 10 business days × 1–2 rounds |
| Mill order to delivery | 6–12 weeks | 6–12 weeks (placed earlier) |
Risk and warranty comparison
On a multi-vendor project, when a connection fails inspection or a beam is fabricated to the wrong length, the GC arbitrates between the SER, the connection engineer, the detailer, and the fabricator to assign cost. Each party has separate insurance and separate contractual carve-outs.
On a single-source project, the provider owns the issue end-to-end. AISC 303 §4.5 still governs — the fabricator is responsible for dimensional accuracy of the shop drawings — but there is no contractual gap between SER and fabricator's engineer because they are the same firm.
When multi-vendor is the right call
- Public bid environments with mandatory competitive tendering
- Projects above 1,500 tons where competitive fabrication bids drive meaningful savings
- Owners with a long-standing in-house SER they prefer to use
- Specialty fabrication (CMF bridges, hot-dip galvanizing at scale, blast-resistant) where a specific shop is the only viable bidder
When single-source wins
- Schedule-driven projects (data centers, industrial expansions, hospital build-outs)
- Misc steel and equipment supports where the engineering is small relative to the fabrication
- Projects with significant delegated connection design (SCBF, SMF, EBF in SDC D–F)
- HCAI hospital projects where SER + AISC-certified fabrication + special inspection need tight coordination
- Out-of-state projects where the owner doesn't have local fabricator relationships
How PANACHE ENGINEERING delivers single-source
We provide engineering design, PE-stamped delegated connection design, AISC 303 shop drawings, and managed fabrication through a vetted nationwide network of AISC Certified partner shops with AWS D1.1 certified welders. One contract, one PE/SE stamp, one warranty. See our structural steel fabrication services page, read our companion guides on AISC Certified Fabricator endorsements and the AISC 303 shop drawing workflow, or contact our team with your S-sheets and a tonnage estimate for a fixed-fee single-source quote in 48 hours.