Contract Change Management (EPC)
A beginner's guide to contract change management — spot a change, give notice, price it, and authorise it before the work is done, so a routine change order never becomes a dispute. Built on AACE 100R-19.
What exactly is a "change"?
When a contract is signed, three things are fixed: the scope (what will be built), the time (by when), and the price (for how much). Together they form the contract baseline — the promise both parties made.
Two doors: directed and constructive
Change enters a project through one of two doors. The first is obvious; the second is the one that sinks projects. Telling them apart is the most important distinction in this lesson.
| Directed change | Constructive change | |
|---|---|---|
| How it happens | Formally instructed in writing — a change order, field directive, or variation | The contractor is effectively forced beyond the contract, with no formal order |
| Typical cause | The owner decides to add or alter scope | Defective design, over-inspection, denied access, a disputed interpretation |
| Is a change obvious? | Yes — everyone agrees a change occurred | No — the change is real but the paperwork is missing |
| Where it ends up | A priced, agreed change order | A claim — argued later, with the burden on the contractor |
A rarer beast is the cardinal change — a change so large or fundamental that it falls outside the contract's "changes" clause entirely, effectively a new contract. Most changes are nowhere near cardinal; they're incremental adjustments handled through the change-order process.
The change-order lifecycle
A well-run project turns every potential change into an authorised change order through the same six steps. Skipping one is where money and time leak away.
- Identify — recognise a deviation from scope, time, or price and log it the moment it appears, before any work proceeds.
- Notice — notify the other party in writing within the contract's time limit; this preserves the right to claim and lets the owner mitigate.
- Price & time — quantify the added cost and any schedule impact: build the cost bottom-up, model the time as a fragnet.
- Negotiate — agree the scope, value, and any extension of time, supporting every number with verifiable backup.
- Authorise — both parties sign the change order before the work is done.
- Incorporate — update the budget and schedule baselines and track the change to closeout.
Notice: the clause that can win or lose entitlement
Almost every construction contract requires the contractor to give notice of a change within a fixed number of days — often 7, 14, or 28. Notice isn't bureaucracy: it lets the owner mitigate, inspect conditions before they're covered up, and make an informed decision. Miss the window, and a contractually valid change can be barred purely on a timeliness defence — the money was owed, but the right to claim it expired.
Worked example — building up a change-order price
A change-order price is built from the bottom up: direct costs first, then the markups the contract allows. The owner directs the contractor to install 12 additional equipment foundations not in the original scope. Here's the build-up.
From direct cost to change-order value
Worked example| Cost element | Basis | Amount (USD) |
|---|---|---|
| Direct labour | 480 hr × $45.00 | 21,600 |
| Material | takeoff | 14,000 |
| Equipment | rental + operating | 6,400 |
| Subcontracted work | quote | 8,000 |
| Direct cost subtotal | 50,000 | |
| Field / site overhead | 12% of 50,000 | 6,000 |
| Home-office overhead | 8% of 56,000 | 4,480 |
| Profit | 10% of 60,480 | 6,048 |
| Bond & insurance | 1.5% of 66,528 | 998 |
The markups compound — each tier applies to the running subtotal, so the order they stack in matters and must follow the contract. And you never invent the percentages: the contract dictates them.
Change-order price calculator
Drag the sliders. Overhead, profit, and bond compound on the running subtotal, in order.
Change-order build-up
Try it yourselfDrag the sliders. Overhead, profit, and bond compound on the running subtotal, in order.
The change register — your single source of truth
On a live project, changes arrive faster than they close. The change register is the running list of every potential, pending, and authorised change: its number, description, status, estimated value, time impact, and notice date. It's how the project knows its true forecast cost and completion date at any moment — not the stale numbers in the original contract.
| Capture this | So that later you can… |
|---|---|
| Change number, description & status | Track every change through the six lifecycle steps |
| Estimated value & time impact | Forecast the true cost and completion date in real time |
| Notice date & reservation of rights | Prove timeliness and keep entitlement alive |
| Backup documents & correspondence | Support the price and causation if it's ever questioned |
Ten things to remember
- A change moves the baseline of scope, time, or price — manage it on paper, deliberately.
- Change arrives through two doors — directed (formal) and constructive (forced, undocumented).
- A constructive change earns the same entitlement — but you must prove it happened.
- Follow the lifecycle — identify → notice → price & time → negotiate → authorise → incorporate.
- Notice comes before pricing; authorisation comes before the work.
- Miss the notice window and a valid change can be time-barred. When in doubt, give notice.
- Price from the bottom up — direct cost, then the contract's compounding markups, never invented percentages.
- A change can add cost and time — claim the extension of time and prolongation separately.
- The change register holds the project's true forecast cost and completion date.
- Contemporaneous records turn a change into a paid change order instead of a disputed claim.
Glossary
- Cardinal change
- A change so fundamental it falls outside the contract's changes clause.
- Change order
- The authorised, signed document that adjusts the baseline.
- Change register
- The running log of all changes and their status, value, and time impact.
- Constructive change
- Work effectively forced beyond the contract without a formal order.
- Contract baseline
- The agreed scope, time, and price at signing — the reference every change is measured against.
- Directed change
- A change formally instructed in writing by the owner or engineer.
- Extension of time
- Added contract time for an excusable delay, protecting against liquidated damages.
- Notice
- Timely written notification of a change, required to preserve entitlement.