Supplemental Roofing Estimates: What They Are and How to Get One
A supplemental roofing estimate is the document that fixes the gap between what the insurance carrier’s adjuster wrote and what it actually takes to replace the roof correctly. If you’ve ever looked at a carrier’s Xactimate estimate and thought “where’s the drip edge, where’s the ice and water shield, and who’s paying for the steep charge on that 10/12 pitch,” the supplemental estimate is how you get those items paid.
This page explains what goes into one, when to file it, how the process works, and how to decide whether to write it yourself or hand it off.
What a supplemental roofing estimate is
When a homeowner files a claim, the carrier’s adjuster inspects the roof and writes an estimate in Xactimate (or Symbility). That estimate becomes the basis of the first payment. It is almost never the final word.
A supplemental roofing estimate (roofers just say “supplement”) is a revised scope submitted to the carrier after the initial estimate, documenting line items that were missed, underpriced, or discovered once the job started. It’s written in the same Xactimate format the adjuster used, so the desk reviewer can compare it line by line.
Supplements aren’t an argument about whether the roof is covered. Coverage was already decided when the claim was approved. A supplement is an argument about scope and price: this roof needs these materials and this labor to be replaced to code and manufacturer spec, and here is the documentation.
Why the carrier’s estimate comes up short
Three reasons, and none of them are conspiracies.
The adjuster was fast. A field adjuster might inspect six roofs a day in storm season. Ridge vent, starter strip, drip edge and step flashing get missed when you’re on a roof for twenty minutes.
Code items aren’t visible from the roof. Ice and water shield, drip edge and ventilation requirements come from the local building code and the shingle manufacturer’s installation instructions, not from what the adjuster can see. Carriers pay them when they’re documented; they don’t volunteer them.
Things turn up during tear-off. Rotten decking, a second layer of shingles, damaged flashing under the old roof. Nobody knew until the shingles came off, and the original estimate couldn’t include them.
What goes into a good supplemental estimate
The supplements that get approved on the first pass share the same anatomy:
- The carrier’s original estimate, so the reviewer can see exactly what changed.
- A revised Xactimate estimate using the same line-item codes, with each added or changed item clearly identified.
- Photo documentation of every item you’re asking for: the exposed decking, the missing drip edge, the second layer, the pitch gauge on the steep section.
- Code and manufacturer citations for code-required items — the specific section of the adopted IRC or local amendment, and the manufacturer’s installation instructions where they apply.
- Measurements from an aerial report (EagleView, Hover) when the carrier’s squares or waste factor don’t match reality.
- A short, professional cover note explaining what’s being requested and why. One page. Reviewers don’t read manifestos.
What doesn’t belong: emotional appeals, complaints about the adjuster, or items that aren’t storm-related. Each one costs credibility on everything else in the file.
When to file the supplement
Two windows, and most roofers only use one.
Before the work starts. Once you’ve inspected the roof and read the carrier’s estimate, file for the missed and code-required items. Getting these approved up front means your crew installs to the approved scope and you’re not carrying unpaid materials on your books.
After tear-off. File a second supplement for anything discovered during the job, with photos taken before the new roof goes on. This is the one everybody remembers to do.
Roofers who supplement only after the job leave money on the table, because carriers scrutinize post-completion supplements harder and some line items are difficult to prove once they’re covered by new shingles.
How the process works
- Submit the supplement package to the carrier’s claims department (email addresses and phone numbers vary by carrier — we keep a free list).
- Wait for a desk reviewer to compare it against the original. This is where the timeline lives; carriers range from a few days to several weeks.
- Respond to pushback. Common responses: “not storm related,” “not code required in this jurisdiction,” “already included in the line item.” Each needs a specific, documented answer, not a re-send.
- Receive a revised estimate and supplemental payment.
- Follow up every few days until step 4 happens. Supplements that aren’t chased don’t close.
Across the supplements we’ve handled, the historical average from submission to a revised estimate is about 19 days, and the average increase is 28.6% of RCV. Both numbers vary heavily by carrier: some carriers routinely pay code upgrades, and some rarely do. Treat them as averages, not promises.
Write it yourself or hand it off?
You can write supplements in-house if you have someone with Xactimate access, current pricing, knowledge of the local code, and — the part most roofers underestimate — the time to follow up with the carrier every few days for three weeks on every open job. For a shop doing a handful of insurance jobs a month, that can work.
Above about ten jobs a month, the follow-up load alone usually eats a full-time person. That’s the point where a supplemental estimating service starts to pay for itself, especially on a percentage model where you only pay when the supplement produces an increase. We wrote up the actual math at 30 jobs a month if you want to run your own numbers.
How Estimate on Demand handles supplemental roofing estimates
We write and negotiate supplemental estimates for roofers. Our estimators are former insurance adjusters, so they write the supplement the way the desk reviewer needs to see it and know which items need which documentation before the carrier asks.
- Upload the carrier estimate, photos and measurements to your client portal.
- We return the supplement to the carrier within 24 hours of a complete file.
- We chase it — calls and emails — until the carrier issues a revised estimate.
- You pay 10% of the increase, after the job closes. No increase, no fee.
We are not public adjusters. We don’t represent homeowners, assess coverage or inspect damage. We write and negotiate the scope on behalf of the roofer doing the work.
See how our roofing supplement service works → · Pricing → · Talk to us →
Frequently asked questions
What’s the difference between a supplement and a supplemental estimate?
Nothing. “Supplement,” “supplemental estimate” and “supplemental roofing estimate” all refer to the revised scope submitted to the carrier after the initial estimate. Roofers say supplement; carriers and search engines say supplemental estimate.
Can a roofer submit a supplemental estimate, or does it have to come from the homeowner?
The roofer can submit it. The homeowner is the insured party and the payment goes to them (or to them and the mortgage company), but carriers routinely accept scope documentation from the contractor performing the work. Where the line sits legally — and what a roofer should never do — is covered in Can Roofers Negotiate Insurance Claims?
How long does a supplemental roofing estimate take to get approved?
The roofer or their supplement company controls how fast it’s submitted; the carrier controls the rest. Our historical average is about 19 days from submission to a revised estimate, but individual carriers range from under a week to six weeks or more.
Do carriers have to pay for code upgrades?
Only if the policy includes ordinance-or-law coverage (most do, with limits) and the item is actually required by the adopted code in that jurisdiction. That’s why supplements cite the specific code section rather than just saying “code required.”
What if the carrier denies the supplement?
A denial is a response, not the end. Most denials are for missing documentation or a disputed interpretation, and a specific rebuttal with the right photo or code citation resolves many of them. If the carrier holds firm on a covered, documented item, the homeowner has appraisal and complaint options that a public adjuster or attorney can advise on — that’s outside what a supplement company does.
Want the step-by-step version? Read how to write a roofing supplement that gets approved, from former adjusters.