This document is the manufacturer stating that its own products cannot be combined on one building. 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.
Do-not-mix GAF · Roofing · 2023 · 1 page
Technical Support Services Notice: Do Not Mix Timberline HD® and Timberline HDZ® Shingles
In their own words
GAF does not recommend mixing Timberline HD® Shingles that have been discontinued with the Timberline HDZ® Shingles currently being manufactured; this is due to changes in sizes, manufacturing, color, and granule sourcing.
GAF — Technical Support Services Notice: Do Not Mix Timberline HD® and Timberline HDZ® Shingles, 2023
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 Services Notice: Do Not Mix Timberline HD® and Timberline HDZ® Shingles
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
This is the argument carriers least expect, because it does not come from you. When the manufacturer says two of its own products may not share a roof, a repair that combines them is not a cheaper way of doing the job — it is a defective installation, and the party who directed it owns the outcome.
- 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 HDZ
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.
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 Pinnacle
Three separate dimensional eras of the same product name. Pre-2013 Pinnacle measured 38¼″ × 13⅛″ at a 5⅝″ exposure; 2013–2017 measured 39⅜″ × 14″ at 6″; 2017-on measures 42″ × 14″ at 6″. A “Pinnacle roof” tells you almost nothing until you know which era.
Atlas Pinnacle · StormMaster Shake
Effective July 2, 2013 Atlas changed the dimensions of both lines — from 38¼″ × 13⅛″ to 39⅜″ × 14″ — and stated plainly that the two generations cannot share a roof deck.
Atlas Pinnacle Pristine
Atlas states a do-not-mix condition between the original Pinnacle Pristine and every later version. It no longer manufactures a shingle at a 5⅝″ exposure or 39⅜″ length, and the current HP42 cannot be installed on the earlier roof.
CertainTeed Landmark and related lines
Even where the product name has not changed, CertainTeed identifies three conditions that defeat a partial repair on an aging roof: the older shingles have lost pliability, the granule blend has been reformulated, and lines such as Landmark converted from English to metric dimensions.
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 770-230-2616
