Supplements Are Change Orders. Bill Them Like It.

Every restoration owner I talk to has the same story about the same job. The scope was approved, the crew mobilized, and then somebody opened a wall and found the water had traveled two rooms further than the adjuster's estimate said it did. The work got done. The billing never caught up.

That gap is not an accident of your business. It is a measured, documented feature of construction generally, and restoration is the version of it with the widest gap and the weakest habits.

The idea: changes are 11-15% of the job, not a rounding error

The commercial construction world has studied scope change for decades, and the numbers are consistent enough to plan around.

The National Association of Credit Management's white paper on change orders cites research finding that the average cost overrun due to change orders runs between 11% and 15% of the original contract value on large building construction, with schedule overruns of 10-20% of the original project duration. The same paper cites an Independent Project Analysis Group study finding roughly 35% of projects experience at least one major change. This is industry data, but it is stable industry data.

The academic side points at why. A peer-reviewed 2025 study in Engineering, Technology & Applied Science Research modeled change orders against project outcomes using survey data from 127 construction practitioners, and found design changes accounted for 56.5% of cost overruns and 40% of delays, with planning errors accounting for another 34.5% and 23.1%. Worth being straight about the limits: that study looked at large-scale projects under a single Indonesian contractor, not American restoration shops. It does not tell you what your jobs do. What it tells you is where overruns come from: changed scope, not lazy crews.

So the ordinary, expected condition of a construction project is that somewhere around an eighth of the contract value shows up after the contract is signed. Nobody calls that a surprise. Commercial GCs staff for it.

The restoration translation

In restoration, that money has a name. It's a supplement.

The Merlin Law Group's property insurance coverage blog puts the equivalence plainly: supplements are contractors submitting documentation for additional funds after the initial claim has been paid, and the process is "similar to 'change orders,' which are often done on non-insurance construction projects." The same piece lists what drives them: damage discovered during repairs, building code requirements, detach-and-reset work, components the adjuster overlooked, and material and labor cost increases between estimate and execution.

Read that list again. Every single item on it is a predictable category, not a freak event. Restoration scope isn't estimated, it's discovered. The adjuster writes a scope from what's visible on day one. Your crew finds the rest on day three.

Here's the part that makes this a cash problem rather than a paperwork problem: on a commercial job, the change order is a negotiation between two parties who both want the building finished. On a restoration job, the party who has to approve your supplement is also the party paying for it, works from a price list that updates on a lag, and has an entire department whose job is reviewing supplements. If you have no process, the friction wins by default.

And absorbing it doesn't look like a loss. It looks like a slightly thin job. Then another slightly thin job. The revenue line never flinches, because you did bill something. The margin per job is where it shows, and most restoration shops aren't measuring margin per job.

Four moves

1. Treat the supplement as a step in the job, not an exception to it. Put it on the production checklist between demo and reconstruction, with a named owner. A process that runs only when someone remembers is not a process.

2. Document at discovery, not at billing. Photos, moisture readings, and a dated note the moment the additional scope is found, before it's covered up. A supplement is only as strong as the evidence that the condition existed and wasn't in the original scope. You cannot reconstruct that after drywall.

3. Measure your supplement rate. Supplement dollars divided by original approved scope, tracked by job and by adjuster. That single ratio tells you whether you have a documentation problem, a carrier problem, or an estimating problem, and those three have completely different fixes.

4. Track supplements as their own receivable line. A supplement restarts the payment clock. If your open supplements sit invisible inside "AR," your cash forecast is wrong by however much is out there. Give them a column.

The point

The industry research says roughly an eighth of a construction contract's value arrives as change. The insurance-restoration version of that money is real, it is legitimate, it is documented in the claim file if you build the file, and it is the single largest pot of revenue most shops are already earning and not billing.

You don't need to be adversarial to collect it. You need a process, evidence taken at the right moment, and a number you actually track. That's bookkeeping and CFO work, not negotiation skill.

If you don't know your supplement rate, that's usually where we start. Our CFO subscription exists to put the job costing and the cash forecast in place so you can see it. Get in touch if you'd like to look at yours.

General guidance for restoration and reconstruction owners, not a substitute for advice tailored to your company's numbers, contracts, or claims.

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