If you build a roof off the estimate the carrier handed you, you are pricing a roof you are not actually installing. The adjuster measured from the ground, wrote fast, and moved on to the next of the eleven roofs they had that day. The work they missed is still real, still code-required, and still covered by the policy.
The document that fixes it is a supplemental roofing estimate. Here is what one actually is, what goes in it, and how to write one an adjuster can approve without picking up the phone.
What a supplemental roofing estimate is
A supplemental roofing estimate is a revised estimate submitted after the original scope of loss, asking the carrier to add or correct specific line items on a claim that is already open.
Three things it is not:
- It is not a second claim. The claim number stays the same. You are amending the amount, not opening a new loss.
- It is not a price negotiation. You are not arguing that the carrier's unit price is too low. You are showing that the quantity or the item itself is wrong.
- It is not padding. Every item on a good supplement is work that will physically happen on the roof and that the policy already covers.
That framing matters more than it sounds. Adjusters approve corrections and escalate disputes. A supplement written as a correction gets handled by the person who opened it. A supplement written as a complaint gets kicked upstairs.
Why carrier estimates come up short in the first place
It is worth understanding the mechanism, because it tells you where to look.
The estimate is written fast. A field adjuster may carry dozens of open claims in a week during a storm cycle. The inspection is measured in minutes and the estimate is written afterward from notes and photos. Nothing about that process is designed to catch a starter strip.
More scopes are now written from the air. Aerial imagery and satellite-based estimating have become standard for the measurement step. They are genuinely good at squares, pitch, and perimeter. They cannot see rotted decking, inadequate ventilation, a second layer, or flashing that was installed wrong in 2004 — and an estimate built from that data will not price any of it.
Price lists lag the market. Carriers price from a regional list that updates periodically. In the weeks after a large storm, when labor and material demand spike locally, the list can sit behind what the work actually costs.
Detail work is the first thing to fall off. The field is obvious. Accessories, code items, and access conditions are the ones that get skipped when someone is moving quickly and is not the person who has to install the system.
None of that is bad faith, and framing it as bad faith in your submission is the fastest way to slow it down. It is a process that produces predictable gaps — which is precisely why the same handful of line items go missing on claim after claim.
Supplemental estimate vs. the original scope
| Original scope of loss | Supplemental estimate | |
|---|---|---|
| Who writes it | The carrier's adjuster | The contractor (usually) |
| When | After the adjuster's inspection | After the scope is reviewed, or after tear-off |
| What it covers | The whole roof | Only the difference |
| What it proves | The carrier's opinion of the loss | That specific items were missed or mis-quantified |
| Typical length | Multiple pages, every line | One page of items plus supporting photos |
The most common mistake is treating the second column like the first — rebuilding the entire estimate from scratch and sending it over. That forces the adjuster to re-review a roof they already scoped, and it reads as a challenge to their work. Show the delta and nothing else.
When to write one
There are three normal triggers, and they happen at different points in the job.
1. Before the job starts — the scope review. You compare the carrier's estimate against your own measurements and the photos from your inspection. This is where most supplements originate, and it is the cheapest place to catch a gap because nothing has been ordered yet. If you have never done this systematically, the line items roofers miss most is the list to check against.
2. During tear-off — hidden damage. Rotted decking, a second layer nobody knew about, a chimney flashing that was never right. The adjuster could not have seen these from a ladder, which makes them among the easiest supplements to justify — but only if you photograph them before you cover them back up.
3. Any time a code requirement applies. Drip edge, ice-and-water shield, and decking attachment upgrades are frequently omitted from a first scope and are frequently required by local code. A code citation is the strongest justification you can attach to a line, because it removes the adjuster's discretion entirely.
What goes in a supplemental roofing estimate
A complete supplement has five parts. Missing any one of them is what produces the "please provide additional information" reply that restarts the clock.
1. Claim identifiers. Claim number, policyholder name, property address, date of loss, and your company's contact information. Put these at the top. An adjuster handling two hundred open claims should not have to search for which file this belongs to.
2. The line items, in the carrier's format. Each requested item listed with its description, quantity, unit, and unit price. Use Xactimate line codes if you can — carriers price in Xactimate, and an item submitted in their own code is an item they can paste straight into the estimate. A plain-English description forces the adjuster to translate, and translation is where things get denied.
3. A reason for each item. One sentence per line. It should name one of three things:
- Manufacturer specification (starter strip is required for the warranty)
- Building code (drip edge is required at eaves and rakes under the local code section)
- Physical condition (decking was rotted, shown in photo 4)
4. Photographic support. Dated, and specific to the item. A wide shot of the roof supports nothing. A close photo of the wall intersection with the failed step flashing supports the step-flashing line.
5. The revised total. The original amount, the supplement amount, and the new total. Show the arithmetic. If overhead and profit applies to the claim it applies to the supplement too, so include it in the math rather than hoping it gets added later.
How to write one, step by step
Step 1 — Get the carrier's estimate in a readable form. You need the actual line-item export, not a summary letter. If you only have a PDF summary, request the full estimate. You cannot compare against what you cannot see. Our guide to reading a scope of loss covers what each section of that document is telling you.
Step 2 — Compare it against the real roof. Your measurements, your pitch, your layers, your accessory counts. Line by line. This is tedious by hand, which is exactly why items get missed — a tired rep at 7pm is not going to catch that ridge cap was priced as cut field shingle. Roofing supplement software does this comparison automatically: it reads the carrier's scope PDF, checks it against the roof, and flags what is missing or under-quantified.
Step 3 — Sort the gaps into two piles. Items with hard justification (code, manufacturer spec, photographed condition) and items that rely on judgment. Lead the submission with the hard pile. Momentum matters — an adjuster who has approved four items in a row approves the fifth more readily than one who started with an argument.
Step 4 — Write one line of reasoning per item. Not a paragraph. Not a letter. One sentence naming the code, the spec, or the photo number.
Step 5 — Assemble everything into a single submission. Estimate, photos, measurement report, code references. One package, one email, one time. Sending items as you think of them turns one review into four.
Step 6 — Log the submission and the follow-up date. Supplements do not chase themselves. The most expensive supplement is the one that was written correctly and then forgotten in an inbox while the crew moved to the next street.
Formatting that gets approved faster
The content decides whether a supplement is valid. The format decides how fast it moves.
- One item per row. Never bundle "flashing and accessories" into one line. Bundled lines get denied as a unit; itemized lines get approved individually.
- Match their units. If the carrier prices ridge cap in linear feet, do not submit squares.
- Number your photos and reference the numbers. "Photo 7" in the reason column, "Photo 7" on the image. This one habit removes most back-and-forth.
- Keep the cover note to three sentences. What claim, what you are requesting, what is attached. Adjusters skim.
- Send it as one PDF. Not eight attachments.
Mistakes that get a supplemental estimate rejected
Re-pricing the whole roof. Covered above, and it is the number one cause of a supplement stalling.
Submitting after final invoice. Once the claim is closed and the depreciation released, reopening it is a different and much slower process. Supplement before you invoice.
No photo for a condition-based item. "Decking was rotted" with no photograph is an assertion. Carriers do not pay assertions.
Quantities that do not tie to a measurement. If you claim 190 linear feet of drip edge, the measurement report should show a perimeter that produces 190. A number that appears from nowhere invites a re-inspection.
Arguing about price instead of scope. Unit pricing comes from the carrier's regional price list. Fighting it is a long road. Fighting the quantity and the missing item is a short one, and it is where nearly all the recoverable money actually lives.
Treating every carrier the same. Different carriers reliably miss different things and reliably push back on different things. Keeping a record of what each one approved last time turns your fifth supplement with them into a much faster one than your first.
What a supplemental estimate typically recovers
Be careful with numbers here, including ours. There is no industry-wide audited figure, and the averages that circulate come from firms with an interest in the number being large.
What is publicly claimed: supplement services citing their own case volume report recovery in the range of $7,000 to $8,000 per claim, and the flat-fee end of the market prices a single supplement around $150. Treat both as vendor-reported rather than measured.
What is more useful than an average is the structure of where the money sits, because that part is consistent:
- Accessory items — ridge cap, starter, drip edge, flashing. Individually small, reliably present on nearly every claim, and rarely disputed once documented.
- Access and complexity factors — steep slope and high roof charges. Larger per line, and driven entirely by whether the pitch and height in the scope match the real roof.
- Code-required work — the largest and most variable category, because it depends on your jurisdiction. Also the most defensible, since a code citation is not a matter of opinion.
- Hidden conditions — decking, second layers, deteriorated substrate. Unpredictable by definition, and only recoverable if photographed before you cover them.
A supplement built on the first three categories is repeatable across every job you run. The fourth is the upside.
Supplement, reinspection, or appraisal — which one you actually need
These get used interchangeably and they are not the same process. Picking the wrong one costs weeks.
| Use it when | Who decides | |
|---|---|---|
| Supplement | The scope missed items or got quantities wrong | The adjuster, usually without escalation |
| Reinspection | The carrier disputes what you documented and someone needs to look again | A second adjuster, on site |
| Appraisal | You and the carrier disagree on amount, not on scope, and the policy has an appraisal clause | Independent appraisers, sometimes an umpire |
Almost everything that feels like a fight is actually a supplement that was under-documented. Exhaust the documentation before escalating — appraisal is slow, occasionally costly, and rarely necessary for a missing drip edge line.
Code requirements vary by state, and so does the argument
The strongest supplement line is one backed by a code citation, but the code is local and the difference is real.
Ice-and-water shield requirements track climate zone. Decking attachment standards have tightened in several hurricane- and hail-exposed states, so a re-roof may legally require re-nailing that the original scope never priced. Some states have specific matching statutes governing whether an insurer must replace undamaged adjacent material to achieve a reasonable match; others leave it to policy language.
Two practical consequences:
- Cite the section, not the concept. "Code requires drip edge" is an assertion. The chapter and section number of your adopted code is a fact the adjuster can verify in thirty seconds.
- Build the list once per jurisdiction, not once per claim. The code does not change between houses on the same street. Most of the work here is a one-time research task that then applies to every job in that market.
If your company works across state lines, this is the single most common place where a rep who is excellent in one market writes a weak supplement in another. Code upgrade coverage is only worth what you can cite.
The part that scales
Writing one good supplemental roofing estimate is a paperwork problem. Writing one on every job is a systems problem.
The crews that collect consistently are not the ones with the best writers. They are the ones where the scope comparison happens automatically on every job, the photos are already attached to the job record from the inspection, and nothing gets marked complete while a supplement is still open. When that is the process, the supplement is a five-minute task instead of an evening.
When it depends on someone remembering, it depends on someone remembering — and on the fourth roof of a long week, they will not.