The short answer: a supplement gets approved on its documentation package, not its argument. The package is: the supplement written in Xactimate format, a cover letter explaining what’s added and why, and a photo for every added item — backed by the working record underneath (moisture readings, dry logs, equipment justification, and references to the applicable IICRC standard). Adjusters approve what they can verify. Everything below is about making every item verifiable.
The package itself: three things, every time
1. The Xactimate file. Correct line-item codes, accurate quantities, organized the way the original estimate was organized. A supplement in any other format — a PDF list, a handwritten scope, a spreadsheet — gets pushed to the bottom of the pile. The carrier’s system reads Xactimate; meet it where it lives.
2. A cover letter. One page: what you’re adding, why each addition exists, and what evidence supports it. This is the map for the reviewer. An adjuster opening a supplement with forty new line items and no cover letter has to reverse-engineer your reasoning. Most won’t — they’ll kick it back with questions that a cover letter would have answered.
3. A photo for every added item. Not a photo of the room — a photo of the specific condition the item addresses, taken before the work was performed. The photo is the item’s witness. No photo, no item. This is the single most repeated piece of advice in every supplement guide written by people who do this for a living, and it’s repeated because it’s where most supplements fail.
The working record underneath
Photos win the item; the working record wins the argument about whether the work was necessary and reasonable. For water losses, the record that carries weight:
- Moisture mapping at the start. Initial readings on every affected material, plus the dry standard for that structure. This establishes what was wet and what “done” looks like.
- Daily dry logs. Each affected material, each day, readings moving toward the dry standard. Gaps in the log are gaps in the story — a five-day drying job with two days of readings invites the question of what happened on the other three.
- Air readings. Relative humidity, temperature, and grains per pound for outside air, unaffected areas, each drying chamber, and dehumidifier output. This is psychrometrics — the science of the drying — and it justifies the equipment.
- Equipment justification. Every piece of equipment on the job needs to match the loss: the right class, the right capacity, the right count. An oversized dehumidifier on a small loss, or sixteen air movers where the math supports six, gets questioned — and the math (IICRC calculations or a drying app) should be in the file.
- Before, during, and after photos. Affected areas before anything is touched. Completed work at each stage. Every piece of equipment installed, photographed in place. The photo record should tell the story of the job without narration.
The standards layer
When an item’s necessity isn’t obvious from the photos alone, cite the standard that requires it. The IICRC publishes the industry’s consensus standards — S500 for water damage restoration, S520 for mold remediation, S700 for fire and smoke. A line item paired with “per IICRC S500” isn’t your opinion anymore; it’s the industry’s documented practice.
You don’t need to quote the standard at length. The reference does the work: it tells the reviewer this isn’t one contractor’s preference, it’s what the profession’s own standard calls for. Keep the standard’s relevance specific — cite it for the item it supports, not as a blanket footer.
The paper trail around the work
- Work authorization. Signed, dated, before work begins. Establishes that the work was authorized and when.
- Scope notes. Category and class of loss, affected areas, what was demolished and the justification for the demolition. Written at the time, not reconstructed later.
- Communication log. When the supplement was submitted, who received it, what was asked for, what was provided. Supplements die in inboxes; the log proves yours didn’t.
- Certificate of completion. Signed by the insured at the end. Closes the loop on the work itself.
What kills a documentation package
The same gaps, over and over:
- No before photos. The most fatal. Once the wall is closed, the condition it covered is unprovable.
- Readings without a dry standard. Numbers with no baseline are just numbers. The dry standard is what makes a reading meaningful.
- Equipment with no math. Dehumidifiers and air movers that don’t match the loss class invite the reviewer to cut all of them.
- Late submission. Documentation assembled weeks after the fact reads as constructed rather than recorded. The record has to be built during the job, not after it.
- The verbal supplement. “I told the adjuster about it on the phone” is not documentation. If it isn’t written, photographed, and submitted, it didn’t happen.
Where this comes from
- From the field (labeled): the detailed working-record checklist — dry logs, psychrometric readings, equipment-justification math, photo staging — reflects guidance shared by working restorers on the MikeysBoard trade forum and in contractor-published claim guides (third-party, not Xactware-official). The documentation hierarchy (professional IICRC-based reports > timestamped photos > itemized estimates > inventories > receipts) comes from contractor-published claim documentation guides.
- Industry standards: IICRC S500 (water), S520 (mold), and S700 (fire/smoke) are the profession’s published consensus standards — cited here as references, not quoted. (The IICRC sells the full standards through its webstore; the linked pages describe each standard’s scope.)
- From Xactimate (official): line-item notes (F9) and the estimate-revision workflow are Xactware-documented functions; the supplement format standard (Xactimate file, coded items, quantities) is the carrier-accepted norm.
- Related on Restoration Intel: When Do I Supplement and When Do I Just Absorb the Cost? — the decision framework this package serves · Which Xactimate Line Items Do Adjusters Actually Approve? — why documentation decides approvals
The supplement is the argument; the documentation is the evidence. Arguments without evidence get denied. Evidence without a supplement never gets submitted. You need both, in that order.