Deck Damage From Old Underlayment and Rusted Nails: Document It

Two conditions show up only once the old roof is off: old self-adhered underlayment that bonds so tightly the deck surface tears when it is removed, and rusted or loosened fasteners that no longer hold. Both can mean the deck needs partial replacement before new roofing is installed. Because the evidence is destroyed when the sheets go in the trailer, the crew has to photograph it on the roof: close shots, a tape, the slope, and a count of sheets. The carrier decides what to pay.

Disclosure: we make Supplement Snap, which helps roofing crews document damage found at tear-off and export a report. It does not decide coverage, negotiate claims or guarantee approval. This page is general guidance, not legal or claims advice.

Torn or delaminated decking is thrown away with the old roof. Rusted nails come off with the shingles. A reviewer who was not on the roof cannot judge what they cannot see, so a description with no photo carries little weight. The table lists what to capture before the material is removed.

Take a close photo of the old underlayment bonded to the deck, then another as the crew lifts it showing what comes with it. If the top ply of the plywood or the surface of the OSB tears away, photograph the torn area with a tape. Do it for each slope where it happens, not just one.

Pull a few shingles back or lift a section of deck and photograph the nail shanks and heads close up. Rusted shanks, nails that have pulled through the deck, and heads that spin freely are all worth a clear shot with a tape. Note which slope and where on it. Our decking documentation guide covers the sheet-by-sheet count.

Write how many sheets or how many square feet on each slope are affected. If you walk the deck and it flexes, or fasteners will not bite, note it as an observation. Do not write that the whole roof is bad unless you have checked every slope.

If you are saying the deck must be replaced to install the new roof, point to something you can show: the shingle manufacturer's deck and fastening requirements, the underlayment maker's instructions, or the building department's requirement. Attach the page, or ask the building department for it in writing. Building codes, manufacturer instructions, policy wording and carrier practice vary, so confirm the details for your job with the building department and the claim documents.

On a steep rear slope, the crew peels back an old self-adhered underlayment. The top ply of the plywood comes up with it in strips. The lead photographs the bonded underlayment, the torn deck with a tape, and a handful of rusted nails with the heads pulling through. He counts nine sheets affected, writes it by slope, and sends the log.

The office builds one finding for the sheets, one for the rusted fasteners, attaches the manufacturer's deck requirements and asks for review. The example is invented. The carrier may decide differently, and some tears can be repaired without replacing the sheet.

Decking, rear slope: 9 sheets with the top ply torn away when old self-adhered underlayment was removed, photos 33 to 38 with a tape. Rusted fasteners pulling through the deck on the same slope, photos 39 to 41. Replacement of affected sheets requested. Manufacturer deck requirements attached.

Keep the torn sheets and the fastener condition as separate findings.

Roofing materials come with installation instructions that usually say what the deck must be, how fasteners must hold, and how to prepare it. Local code may add its own rules. Find the instructions for the shingle and underlayment you are installing, copy the relevant page, and ask the building department in writing if you rely on a code rule. Quote only what you can show. Building codes, manufacturer instructions, policy wording and carrier practice vary, so confirm the details for your job with the building department and the claim documents.

Not every torn spot needs a new sheet. A reviewer may reasonably ask why a section was replaced instead of repaired. Write what you saw and why: for example, the top ply came away over a large area, fasteners would not hold, or the deck flexed underfoot. If you repaired a small area instead of replacing a sheet, say that too. Honest scope builds credibility.

Plywood is made of thin layers glued together. Delamination is when those layers separate, often after moisture or when something bonded to the surface is pulled off. Photograph it with a tape and describe it in plain words: top layer peeled away over about two feet by three feet, for example. Avoid technical terms you cannot back up.