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A RocketLevel playbook for estimators, supplement writers, office managers, and owners, backed by decades of experience in the trade. This is the GEM home for supplements, on commercial and residential claims alike. About an 8-minute read.
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Reviewed October 2026. Public adjusting, insurance fraud and contract rules change, and they vary by state. Use this page to know what to ask, then confirm with your state insurance department or a construction attorney before you rely on it.
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On commercial and large-loss work, the first estimate is rarely the final number. Hidden damage and added scope show up once demolition starts. The supplement is how you get paid for it, and plenty of shops leave supplement money on the table because they treat it as a fight instead of a documentation exercise.
An addition to an approved estimate when hidden damage or extra scope appears after work begins. On larger losses it's normal and expected, and it doesn't mean you estimated badly.
Most honest supplements come from one of four places:
Each one is the gap between a first look and what the building turned out to need, and the file should read that way.
| Why it gets denied | The fix |
|---|---|
| Weak or missing documentation tying the line to real conditions. | Tie every supplemental line to a piece of evidence. |
| Late submission, after the work is buried. | Submit promptly, while the conditions are still provable. |
| No photos, moisture readings, or daily logs supporting the added scope. | Document as you go: photos, moisture and psychrometric readings, and daily logs. |
| Out-of-scope work done with no change order. | Get a signed change order for any owner-authorized addition. |
In our experience, most denials come down to a documentation gap rather than any real disagreement about the loss.
The evidence behind each line can be photos, measurements, readings, and where they apply a building-code citation or the manufacturer's installation specification. Write clear line-item justifications (F9 notes) that explain the why, citing ANSI/IICRC S500-2021 (Fifth Edition) by section where the standard is what drives the line. S500 is a paid document, sold by the Institute of Inspection, Cleaning and Restoration Certification (IICRC) and through the American National Standards Institute (ANSI) store, so quote it by section rather than reproducing its text. Get written approval before performing supplemental work wherever the scope allows it, because work done ahead of approval and buried before anyone could see it is one of the most common denials.