How to Compare Structural Steel Subcontractor Bids (Without Getting Fooled by the Lowest Number)
The lowest total isn't the same as the best value. Here's a systematic, line-by-line method for evaluating competing structural steel bids so you catch scope gaps before award, not after.
Why Steel Bids Are Hard to Compare
Structural steel bids come back looking deceptively comparable — a lump-sum number on each proposal, sometimes with a one-page scope summary. The problem is what's hiding underneath that lump sum: different bidders make different assumptions about what's included in supply versus erection, whether fireproofing and painting are separately priced or bundled, whether threshold building inspection costs are carried, and how much contingency is baked into (or excluded from) the number. Two bids that look $50,000 apart on the surface can represent two entirely different scopes of work.
This is precisely the problem a well-structured BOQ solves at the tender stage — by forcing every bidder to price against the identical, itemized scope. But even with a good BOQ issued, it's the owner or GC's job to verify that every bidder actually priced every line, rather than silently excluding items they assumed were someone else's scope.
It's also worth naming why this problem is worse for structural steel specifically than for many other trades. Steel pricing involves several genuinely separable cost layers — mill material, fabrication labor, shop overhead, transport, erection labor, crane time, and connection installation — each of which a bidder can choose to bundle or itemize differently. A drywall or painting bid, by contrast, usually has far fewer moving cost layers to obscure. The more layers a scope has, the more places a bidder has to quietly shift cost around, which is exactly why steel bids reward the kind of disciplined, line-by-line comparison this guide walks through.
A Line-by-Line Comparison Method
Rather than comparing bottom-line totals, build a comparison matrix with every BOQ section as a row and every bidder as a column. This single step — forcing yourself to look at Section A versus Section A, Section B versus Section B, rather than total versus total — is where most genuine scope gaps first become visible, well before any deeper investigation is needed.
| BOQ Section | Bidder A | Bidder B | Bidder C |
|---|---|---|---|
| A. Supply of Structural Steel | $3,650,000 | $3,590,000 | $3,890,000 |
| B. Erection at Site | $610,000 | $705,000 | $598,000 |
| C. Connections, Fasteners & Welding | $195,000 | Not itemized | $212,000 |
| D. Surface Protection | $1,140,000 | $980,000 | $1,205,000 |
| G. Testing, Inspection & QC | $125,000 | Not itemized | $131,000 |
Start With a BOQ Bidders Can't Wiggle Out Of
Our 8-section, 60-item template gives you the itemized structure needed to force apples-to-apples bids from every subcontractor.
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A number that comes in meaningfully below its competitors deserves a closer look before it gets treated as good news. Sometimes it genuinely reflects a bidder's efficiency or current market advantage — but often enough, it reflects a specific, identifiable gap that a careful reviewer can spot with the right questions.
Missing Sections
If a bid doesn't itemize testing/QC or surface protection separately, ask directly whether it's included, excluded, or forgotten — "not itemized" is not the same as "included."
Unusually Low Erection Cost
Erection cost is dominated by crane time and labor; a number dramatically below competitors often signals an unrealistic schedule assumption or missing safety/mobilization cost.
No Rate Back-Up Offered
A bidder unwilling to show how they built a key rate may be quoting from gut feel rather than a real cost build-up — a risk factor in itself.
Vague Exclusions List
"Excludes miscellaneous items as required" is not a real exclusion — ask for a specific, itemized exclusions list before comparing numbers.
Normalizing Scope Before Comparing
Before the comparison matrix means anything, normalize scope across bidders: confirm identical steel grades and code references, identical fireproofing rating requirements, identical bolt grades, and identical crane/mobilization assumptions. If one bidder assumed a shorter erection schedule requiring two cranes running simultaneously and another assumed a single-crane sequential erection, their Section B numbers aren't comparable until that assumption is called out and reconciled.
A practical way to force this normalization is to require every bidder to submit their proposal against your own issued BOQ line numbering, rather than accepting a bidder's own reformatted proposal layout. When Bidder B's "Section B" doesn't map cleanly to your Section B, you've already lost the ability to compare cleanly — and you're now relying on that bidder's own narrative description of what's included, which is precisely the scenario a good BOQ is designed to prevent.
Using the RFI Process Before Award
Once your comparison matrix surfaces a gap — a missing section, an unusually low number, a vague exclusion — the right next step is a formal, written clarification request to that specific bidder, not an informal phone call that leaves no paper trail. A written RFI (Request for Information) sent to all bidders equally, asking each to confirm or clarify a specific line item, keeps the process fair and creates a documented record of exactly what each bidder committed to before award. This matters enormously if a dispute arises later over whether a scope item was included — a documented pre-award clarification is far stronger evidence than a recollection of an informal conversation.
Build enough time into your tender schedule for at least one clarification round before the award decision. Bidders who receive a specific, well-targeted clarification request and respond with a clear, complete answer are demonstrating exactly the kind of responsiveness and transparency you want from a contractor once the project is underway; bidders who respond evasively or push back on providing clarity are showing you that same behavior pattern before you're contractually committed to them.
When to Ask for Rate Back-Up
For your highest-value line items — typically supply and erection of primary members, and any provisional or unusual item — it's reasonable and standard practice to request a rate analysis showing the material, labor, overhead and profit build-up behind the number. A bidder confident in their pricing will produce this without pushback; reluctance is itself informative. This is exactly the visible-rate-analysis discipline described in standard quantity-surveying methodology.
When you review the rate back-up you receive, look specifically at the material cost basis (is it current, or is it a stale quote from months earlier), the labor productivity assumption (does it match realistic crew output for your site conditions), and the overhead and profit percentage (is it in a normal range for the market, or unusually thin in a way that might signal a bidder under pressure to win work regardless of margin). Any one of these being off doesn't necessarily disqualify a bid, but it should factor into your overall risk assessment of that bidder.
Rate Analysis, Built In
Our template includes live rate-analysis blocks for 3 key items — a working example of exactly the back-up detail you should expect bidders to be able to produce.
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Once scope is normalized and pricing has been scrutinized line-by-line, the final layer of diligence is assessing the bidder as an organization you're prepared to work with for the duration of the project, not just as a number on a page. Price comparison is necessary but not sufficient. Also weigh: AISC fabricator/erector certification status, bonding capacity relative to contract value, safety record (EMR/experience modification rate), current backlog and schedule availability, and references from comparable recently completed projects. A bid that's 3% higher from a certified fabricator with strong safety metrics and available capacity often represents lower total project risk than the absolute lowest number from an unproven or overcommitted shop, particularly on a schedule-sensitive project where a missed milestone cascades into costly downstream delay claims from other trades. Weighing these factors alongside price, rather than as an afterthought once price has already decided the outcome, is what separates disciplined bid evaluation from a simple lowest-number selection process.
References deserve more diligence than they typically get. Rather than accepting a generic reference list, ask each bidder for a project of comparable size and complexity completed within roughly the last two years, and actually call the reference — asking specifically about schedule performance, change order frequency, and responsiveness to field issues, not just "were you satisfied." A bidder's most recent, most comparable project tells you far more about what to expect than an older project completed under different market conditions and a different project team.
Frequently Asked Questions
No — but never accept it without understanding exactly why it's lower. Sometimes it reflects genuine efficiency; sometimes it reflects a scope gap that surfaces as a costly change order after award.
Focused detail on your highest-value or highest-risk items is standard and reasonable; asking for a full rate analysis on every single line item is usually excessive and can slow the tender process unnecessarily.
Comparing lump-sum totals without first normalizing scope assumptions — different fireproofing ratings, different crane strategies, or different inspection scope hidden inside an otherwise similar-looking number.
It reduces the risk significantly by forcing itemized pricing, but doesn't eliminate the need to verify bidders actually priced every line rather than silently omitting scope.
Yes — any clarification that changes or confirms scope should be explicitly incorporated by reference into the executed contract, so it carries the same binding weight as the original bid documents.
Three to five qualified bidders typically produces a healthy comparison — fewer than three limits your ability to spot outliers, while significantly more can slow the tender process without meaningfully improving the outcome.
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