Change orders are where fabricators make or lose money on otherwise profitable contracts. A shop that bids tight to win work but handles changes poorly can end up in the red. A shop that documents and prices changes well can improve margins on every affected job.
Here's how to approach steel change orders without getting burned.
Why Steel Change Orders Are Different From General Construction COs
Steel fabrication has characteristics that make change orders more financially impactful than in other trades:
Material procurement is upfront. You've already bought steel based on the original design. A design change that replaces a W16x40 with a W18x50 means steel already procured may be unusable — or requires reorder at current (possibly higher) pricing.
Shop time is scheduled. Fabrication shops run on production schedules. A late design change that requires rework pulls capacity from other jobs. The true cost isn't just the rework time — it's the schedule disruption.
Detailing costs are real. When a structural change requires new shop drawings, the detailer charges for it. That cost belongs on the change order.
Lead time creates pricing windows. If a change arrives after material is procured but before fabrication, material repricing is limited. If it arrives after fabrication has started, you're adding labor and rework that's much harder to estimate accurately in real time.
The 5 Types of Steel Change Orders
1. Member additions
New members added to the scope — an added column, a mezzanine extension, additional brace frames. These are the cleanest to price: material cost + fabrication labor + connection hardware + detailing + markup.
2. Section substitutions
Engineer changes W18x35 to W21x44 at a specific member line. Price the material delta (new section weight vs. original, at current pricing), plus any connection rework if the bigger section changes the connection design.
3. Connection changes
Moment frame connection added where a simple shear connection was specified, or a field-welded connection changed to bolted. These can be significant — moment connections add fabrication hours, sometimes special inspection requirements, and potentially stiffener plates.
4. Deletion credits
Members removed from scope. Your credit should reflect only your actual cost recovery, not list pricing. Material that's already purchased may be restockable at a fee (or may not be restockable at all for non-standard sizes). Labor not yet performed is credited at cost. Overhead and profit on deleted work should not be credited at full markup.
5. Sequence and timing disruptions
The most expensive and hardest to price. A change that forces you to set aside work-in-progress, reschedule a crane delivery, or hold material on the shop floor for 3 weeks has real costs that go beyond the direct change scope. Document these carefully.
How to Build a Steel Change Order Price
A clean change order format should include:
| Component | Calculation Method | |---|---| | Material (additions) | Tonnage × current material cost/ton | | Material (substitutions) | Delta weight × current cost/ton | | Fabrication labor | Hours × fully-loaded shop rate | | Detailing/engineering | Actual cost or estimate | | Connection hardware | Bolt count × unit price | | Shop drawing revisions | Hours × detailer rate | | Restocking/repricing | Actual supplier charge | | Delay/disruption | Documented actual cost | | Overhead | % of total direct costs | | Profit | % of total cost |
Don't undercut your profit on change orders. Change orders are legitimate scope additions. Shops that price them at cost to "keep the relationship" train owners and GCs to push changes through without scrutiny.
Change Order Markup: What's Reasonable
There's no universal standard, but industry norms in structural steel fabrication:
Material markup: 10-20% above cost. This covers purchasing overhead, storage risk, and the pricing exposure on procurement timing.
Labor markup: 15-25% above direct labor cost for overhead, plus your normal profit margin (typically 8-15%).
Subcontracted work: 10-15% markup on pass-through costs (detailing by outside detailer, special inspection, etc.).
On small COs (under $5,000): Consider a minimum charge that covers your administrative cost of processing the change order itself. Preparing pricing, reviewing drawings, getting approval, and billing a $1,200 change order might consume $400 in administrative time.
Documentation That Protects You
T&M authorization before work proceeds
For changes discovered during fabrication, get a written T&M (time and materials) authorization before proceeding — even if it's an email. This prevents "we never approved that" disputes later.
Photograph affected work
For scope that's already fabricated and needs rework, photograph before and after. Images are evidence when disputes arise.
Track labor separately
Use a distinct job cost code for change order work. When you're billing at the end, you have actual labor records, not estimates.
Issue change orders promptly
Don't batch changes and bill them all at project closeout. Changes priced 6 months after the fact are harder to defend and harder to collect. Price and issue within 2 weeks of identifying the change.
Reference the original scope in your CO
A change order should reference the specific drawing revision (Rev 2, Sheet S-3, dated 2026-01-15) that triggered the change. This creates a clear paper trail linking the change to its cause.
The Connection Between Takeoff Accuracy and Change Order Clarity
One underappreciated benefit of accurate original takeoffs is that they make change orders cleaner to price. If your original bid was based on a precise, documented quantity list — generated from the drawing set — you can compare it directly against the revised drawing set to identify exactly what changed.
If your original takeoff was approximated or built on rough counts, proving what's a change vs. what was always in scope gets murky.
Tools like SteelFlo generate a complete documented member list from the original drawing set. When revisions come in, you can run a new takeoff on the revised set and compare the two outputs directly. The delta is your change order scope — documented, traceable, and defensible.
The creating accurate bills of materials and how to win more steel bids posts have more on building the documentation habits that protect you through the full project cycle.
Common Change Order Mistakes Fabricators Make
Pricing changes at original bid rates. Your original bid may have included buying power from a bulk material purchase. A change order for 2 extra W18x50s has to be priced at spot pricing, not your bulk rate.
Not charging for detailing rework. Detailing is expensive and often the most underpriced component of a change order.
Giving deletion credits at full markup. You should not credit profit on work you didn't do — but you also shouldn't credit full markup on deleted work. Credit your actual cost recovery on material and direct labor only.
Accepting verbal change authorization. Always get it in writing. Always.
Missing the delay cost. If a change caused you to hold production on other work for a week, that schedule impact has a real cost. Document it and price it.
Frequently Asked Questions
How much should a fabricator mark up steel change orders?
Typical markup on steel change orders is 15-25% on material and labor combined, similar to the original bid. Some fabricators apply a higher markup on change orders to account for administrative costs and the disruption premium. Avoid pricing changes at cost — change orders are legitimate scope and should be priced accordingly.
Can an owner refuse to pay a change order?
An owner can dispute a change order, but if the work was required by a design change (documented with a drawing revision), the fabricator has a strong contractual position. The key is documentation: written authorization, clear scope definition, and a paper trail linking the change to the design revision. Disputes that reach arbitration or litigation almost always come down to documentation quality.
What is the difference between a change order and a field order?
A field order (also called a work directive) authorizes work to proceed before full pricing is agreed — typically on a time-and-materials basis. A change order is the formal contract amendment with agreed pricing. Fabricators should insist on written field orders before proceeding with change work, then convert them to formal change orders with agreed pricing as quickly as possible.
How do you handle steel changes when material has already been procured?
Disclose the material procurement status immediately when a change is identified. For additions, price at current market. For substitutions that make procured material unusable, document the cost of the procured material, its potential resale/restock value, and the cost of the replacement material. Include any supplier restocking fees in the change order.
How long should a change order be valid?
Steel change orders should typically be valid for 15-30 days due to material price volatility. State the expiration date explicitly on the change order document. If the change order is not executed within the validity window, you have the right to reprice based on current material costs.