June 25, 2026

Change orders: where they actually come from

Talk to owners who’ve had a rough project and you’ll hear change orders described like weather — something that happened to them. But changes have causes, the causes cluster into four groups, and most of the clusters trace back to decisions made long before the first claim landed.

Understanding the four sources doesn’t just explain your last project. It tells you exactly what to fix on the next one — because three of the four are heavily preventable, and the prevention is boring, cheap and reliable.

The four sources of every change order

Design gaps. The documents were incomplete, uncoordinated or ambiguous, and the contractor is pricing the difference between what was drawn and what a working building requires. On rushed projects this is the biggest category by far — and it’s really a preconstruction failure arriving late. Tender from unfinished documents and the contractor finishes the design for you, priced as changes, without competition. We’ve covered the mechanism in the real cost of skipping preconstruction.

Site conditions. The ground or the existing building held a surprise — soils, water, contamination, structure that doesn’t match the record drawings. This is the most stubborn category, but it shrinks dramatically with proper investigation. Every geotechnical bore and every exploratory opening is a change order you bought at a discount before it could be sold to you at retail.

Owner decisions. You changed your mind — which is your right, and costs money. A tenant shifted requirements, marketing wanted a better lobby, operations needed a different layout. This category isn’t bad; it’s just yours. What makes it dangerous is when it goes untracked and unbudgeted, quietly consuming contingency meant for genuine unknowns.

Errors. Someone got it wrong — a dimension, a spec, a quantity. Smallest category on well-run projects, never zero anywhere humans draw buildings.

Prevention, by category

The unglamorous truth: change-order volume is mostly determined before tender.

• Design gaps shrink with complete, coordinated, clash-checked documents — and with a pre-tender review that hunts specifically for the silences bidders will price later.
• Site conditions shrink with investigation money spent early. Bores, surveys, utility locates, exploratory demolition on renovations. The most reliable ROI in construction.
• Owner changes shrink with decision discipline: major choices — finishes, equipment, layouts — locked before pricing, and a decision calendar that keeps late answers from becoming late changes.
• Errors shrink with review time, which is another way of saying schedule honesty during design.

Projects that invest in all four routinely run total change volumes in the low single digits as a percentage of contract value. Projects that don’t can run several times that — with each change priced at site rates, under schedule pressure, without competition.

Managing the changes that come anyway

Some changes are legitimate and necessary. The goal isn’t zero — it’s discipline, and discipline was set (or not) in the contract you signed. The essentials, which we detail in five questions to ask before you sign:

• Pricing from agreed contract rates, not invented ones, with markup rules that don’t stack through tiers
• Backup that survives scrutiny: quantities, hours, quotes — not lump sums with adjectives
• Submission deadlines, so claims arrive while the work is fresh and verifiable, not accumulated into a year-end ambush
• Entitlement checked before pricing — is this actually a change to the contract documents, or was it always in scope? The question that gets skipped most and pays best
• A running change log reviewed monthly, with approved, submitted and anticipated changes visible against contingency

Read the trend, not just the total

Track changes by cause code, not just by dollars. The distribution diagnoses the project:

Heavy on design-gap changes? You have a documents problem — expect more, and consider a completion review before the next phase tenders. Heavy on owner changes? A decision-making problem — the fix is in your own boardroom. Heavy on site conditions early? Check whether the investigations were actually done, and whether the contingency structure can absorb what’s coming.

The dollars tell you it hurts. The causes tell you what to fix — on this project, and permanently.

Frequently asked questions

What’s a normal change-order percentage?

On new construction with complete documents, low single digits of contract value is achievable and common. Renovation and heritage work runs structurally higher. Treat double digits as a symptom demanding a cause-code review, not a market condition to accept.

Should I pay for changes the contractor performed without approval?

The contract answers this — which is why its change article matters. As a practice: hold the line that unauthorized work is at the contractor’s risk, while fixing whatever approval bottleneck tempted them to proceed. Both halves matter.

Who should review change-order pricing?

Someone who has priced work themselves and answers only to you. Design consultants confirm scope legitimacy; verifying hours, rates and quantities is estimating work — the same muscle as independent estimating, applied retail. It’s a standard part of our owner’s representation scope.

Watching a change log grow faster than your contingency? Send us the log — the cause codes usually tell the story within a day.