This document is the manufacturer rejecting or limiting spot repair as a method. The obvious workaround — trim a modern shingle down to the old dimensions — is one GAF specifically rejects, because cut shingles may not seal to one another.
Repair methodGAF · Roofing · 2024 · 1 page
Technical Support Letter — Cutting Timberline HDZ Shingles Not Recommended
In their own words
GAF does not recommend cutting the GAF Timberline® HDZ Shingles… to repair the roof with GAF shingles or other manufacturer’s shingles that are smaller in size in the field of the roof as they may not be compatible when sealing to one another.
GAF — Technical Support Letter — Cutting Timberline HDZ Shingles Not Recommended, 2024
That sentence is not our characterisation of the manufacturer’s position. It is the manufacturer’s position, in the document below, which you can read yourself in about a minute.
Get the document
Technical Support Letter — Cutting Timberline HDZ Shingles Not Recommended
Issued by GAF. Published here complete — no summary standing in for the document, no email required.
Issued by GAF. Held in this firm’s reference library; not published elsewhere. Homeowner-identifying details, where a letter was addressed to a particular property, are blacked out — nothing else is altered, and no operative text is ever redacted.
What to do with it
Adjusters write "repairable" as though it were a finding. It is a conclusion, and this document is the manufacturer disagreeing with it. Building codes require installation to follow the manufacturer's instructions, which turns a technical bulletin into a compliance argument.
- You have the manufacturer’s document. That part is finished. Most homeowners never get this far, and it is the step a carrier cannot argue with — it is not your opinion, it is the company that made the product.
- Put it in writing, to the adjuster, with the claim number. Attach the document and ask one specific question: name the exact replacement product — manufacturer, line, colour, dimensions, exposure, nail zone, sealant design, supplier, quantity available locally — and who will answer for the repair if it fails. Vague answers are the whole game; a specific question ends it.
- Get the position on the record before anything gets installed. Once a mismatched or incompatible repair is on the building, you are arguing about something already done.
If you want the second and third steps handled by someone who does this for a living, that is what we are for — and the review costs nothing. If you would rather do it yourself, the document above is yours either way. That is the point of publishing it.
Related documents
Other GAF documents
GAF Timberline HD
The most-installed architectural shingle in America, discontinued July 1, 2020 across every U.S. sales area and every colour, effective immediately. The stated alternative, Timberline HDZ, is a different product — see the do-not-mix letter below.
GAF Timberline HD vs. Timberline HDZ
The companion to the discontinuation notice, and the one that closes the loop: the successor product cannot be used to patch the old one. GAF withdraws warranty coverage where the two are mixed.
GAF Timberline UHD
Discontinued March 6, 2023 in all sales areas — and the notice forecloses the substitute in the same breath.
GAF Grand Slate · Grand Slate II
Discontinued in all colours effective March 25, 2013, with GAF acknowledging that no exact replacement product exists.
GAF Capstone Lifetime Designer
Discontinued February 2012 with no remaining supply channel — confirmed by GAF’s Director of Timberline HD & Designer Shingles.
GAF Sentinel (vs. Royal Sovereign)
Sentinel® was discontinued August 24, 2015 in all colours and all sales areas. The obvious substitute — Royal Sovereign, GAF’s other three-tab — is one GAF declines to recommend.
Other manufacturers saying the same thing
Atlas Chalet
The strongest document in this library. A carrier proposed fixing a Chalet roof by swapping in “comparable” shingles, or by cannibalising shingles from less visible slopes. Atlas’s Consumer Services Manager answered in writing — and the answer is no.
CertainTeed roof repair guidelines
CertainTeed’s own repair standard rejects reusing shingles and forbids intermixing metric and English (standard) sizes on one roof. Building codes require installation to follow the manufacturer’s instructions — which makes this document a code argument, not just a preference.
CertainTeed hail damage
CertainTeed’s technical position on what hail does to an asphalt shingle, and what its warranty does and does not cover afterwards.
Owens Corning hail damage
The plainest rejection of spot repair in this library, from the manufacturer rather than from us. Owens Corning also states that once hail dislodges granules and exposes the asphalt, the roof’s performance has been compromised.
The rule this document serves
Your policy promises repair or replacement with material of like kind and quality. That is a replacement-cost and indemnity obligation, not an appearance theory — and it is why “matching” is the carrier’s word, not the policy’s. Where the installed product cannot be bought, or cannot be combined with what is still sold, the covered building cannot be restored to like kind and quality by patching it, and that is true before anyone argues about how it looks. The full doctrine, and the other 125 documents, are on the discontinued materials hub.
You have the manufacturer's document. The next part is the argument. Handing a carrier a technical bulletin and getting it honoured are two different jobs. The case review is free, and you pay nothing unless we recover.
See if my case qualifies 877-650-3515