An algae-resistant shingle warranty is a narrow promise: if blue-green algae stains the shingles black, the manufacturer will pay to clean them or, at its option, replace them. The number of years depends on the brand, the shingle line, and whether the roof carries the matching hip and ridge pieces. The long terms, 25 and 30 years, are the ones that come with conditions.
This guide covers GAF, Owens Corning, CertainTeed, Atlas and IKO. It does not say what your homeowners policy pays. That is a question for your policy and your insurer.
What causes black streaks on a roof?
Most black streaks are blue-green algae, a cyanobacterium named Gloeocapsa magma. GAF describes it as a bacteria that travels on the wind and thrives in moist environments, so if one house in a neighborhood has it, others have probably been exposed too (GAF). The Asphalt Roofing Manufacturers Association calls it probably the most prevalent of several algae species behind roof discoloration, and says warm, humid climates favor growth (ARMA).
GAF’s technical bulletin says the growth generally shows up on the northern exposures of a roof, and that the stains tend to cover more of the lower roof and thin out toward the ridge (GAF Technical Bulletin R-102). The algae warranties treat black streaks as discoloration and cover only that.
Be careful with cleaning. GAF says power washing may dislodge granules, and ARMA says not to use a power washer. Owens Corning excludes damage from power washing and from cleaning solutions that do not follow its algae removal instructions. Ask the manufacturer before anyone cleans a roof that is under warranty.
What are algae-resistant granules?
They are the colored mineral granules on the shingle surface, made or treated so that they release copper slowly. GAF calls its version Time-Release Algae-Fighting Technology and says it uses thousands of copper microsites that release copper over time; its Timberline UHDZ carries 10% more of that technology than the 25-year shingles. CertainTeed’s and Owens Corning’s warranties refer to copper released by algae-resistant granules. Atlas uses copper-containing granules with a 3M Scotchgard Protector coating.
Two cautions from the warranties themselves. First, Owens Corning says algae-resistant shingles are available regionally, so check that the line and color you want come in an algae-resistant version where you live. CertainTeed’s algae term applies only to the shingle version designated AR. Second, both Owens Corning and CertainTeed warn that in areas with little rainfall or salt fog, copper released by the shingles can corrode aluminum gutters, and neither will cover that damage.
How long is the algae warranty on each brand?
The table below is read from each manufacturer’s current page or warranty, on October 19, 2026. Terms are tied to the edition of the warranty and the install date, so confirm against the document that applies to your roof.
| Brand and line | Algae term | Non-prorated period | What the long term requires |
|---|---|---|---|
| GAF StainGuard | 10 years | 1 year | Shingles in packages labeled StainGuard. |
| GAF StainGuard Plus (Timberline HDZ, AS II, HDZ RS, Grand Sequoia, Camelot II, Slateline, Woodland; GAF ridge caps and StarterMatch starter strips) | 25 years | 10 years; GAF says it may be 15 with an enhanced warranty bought through a contractor in GAF's enhanced-warranty program | Only products sold in packages bearing the StainGuard Plus logo. GAF gives no algae coverage on its other accessories. |
| GAF StainGuard Plus PRO (Timberline UHDZ) | 30 years | 10 years; same 15-year possibility | Only products sold in packages bearing the StainGuard Plus PRO logo. |
| Owens Corning (Duration Series, Woodcrest, Woodmoor, Oakridge) | 25 years | 10 years | An Owens Corning hip and ridge shingle: DecoRidge, DuraRidge, ImpactRidge, ProEdge or RIZERidge. Without one, the term drops to 10 years with a 1-year non-prorated period. Owens Corning Supreme: 10 years. |
| CertainTeed Landmark PRO, Landmark Premium, Landmark TL, NorthGate ClimateFlex, Grand Manor, Carriage House, Belmont, Highland Slate and the Presidential Shake lines | 30 years | Prorated after 15 years | The AR version of the shingle, plus CertainTeed AR hip and ridge accessories. Otherwise the term is limited to 10 years. |
| CertainTeed Landmark, Landmark ClimateFlex and XT 25 | 25 years | Prorated after 10 years | Same: AR shingle plus AR hip and ridge. Patriot and Patriot XL: 10 years regardless of accessories. |
| Atlas Scotchgard Protector lines (StormMaster Shake, Pinnacle Impact, Pinnacle Sun, Pinnacle Pristine) | Lifetime of the original owner on single-family detached homes; 25 years on other properties. ProLam (ARS): 10 years | 10 years (Premium Protection Period); after that, Atlas pays to clean only. ProLam: 1 year | StormMaster Hip & Ridge, Pro-Cut High Profile Hip & Ridge or Pro-Cut Hip & Ridge shingles featuring Scotchgard Protector (or the shingles used as their own hip and ridge). |
| IKO Cambridge (not Cambridge Cool Colors) | 10 years (blue-green algae) | 1 year; after that, a prorated payment toward cleaning only | IKO’s warranty requires IKO hip and ridge products (Marathon Plus AR, UltraHP, Hip & Ridge 12, Hip & Ridge Class 4 or an IKO-approved equivalent). |
Atlas terms are from Atlas’s Standard Limited Shingle Warranty for installs on or after May 1, 2026. IKO terms are from IKO’s US Limited Warranty for asphalt shingles.
What does an algae warranty actually pay?
In the GAF, Owens Corning, CertainTeed and Atlas warranties, the remedy is cleaning, or replacement at the manufacturer’s option. It is not an automatic new roof, and the manufacturer, not the homeowner, picks the remedy.
- GAF: the reasonable cost of commercially cleaning the shingles, ridge caps or starter strips, or, at GAF’s sole option, replacing the discolored ones. After the non-prorated period, GAF says the remedy may be different and is reduced to reflect your use of the product.
- Owens Corning: during the non-prorated period, the cost of repairing, replacing or recovering the affected shingles, including labor, not to exceed the cost of the shingles plus installation. Owens Corning defines “repair” here as cleaning or removing the algae, and decides which remedy applies. In the prorated period it pays a prorated share of the shingle cost only, with no labor. Its example: a claim in the 16th year of a 25-year term is reduced by 16/25ths.
- CertainTeed: it pays to clean or replace the affected shingles, at its sole option. For 25-year coverage the reduction starts after year 10, and for 30-year coverage after year 15. CertainTeed decides whether the staining falls within the warranty. Algae coverage is valid only while the main manufacturing-defect warranty has not expired or been voided.
The insider point. A 25-year algae warranty from GAF or Owens Corning is not 25 years of free cleaning. The full-value window is 10 years on GAF’s and Owens Corning’s 25-year terms, and the years after that pay a shrinking share. On Owens Corning, the share left after the non-prorated period covers shingle cost only, not labor. Compare the non-prorated years as well as the headline number.
Why do the hip and ridge pieces change the term?
The long algae terms are written for a whole roof, not for the field shingles alone. If the pieces on the ridge are a different product, the manufacturer’s own wording shortens the term.
- Owens Corning: without a qualifying Owens Corning hip and ridge shingle, the 25-year algae term is reduced to 10 years and the non-prorated period to 1 year.
- CertainTeed: 25-year and 30-year algae coverage requires CertainTeed algae-resistant hip and ridge accessories. Otherwise coverage is limited to 10 years.
- GAF: the 25-year term applies to products in packages bearing the StainGuard Plus logo, and GAF’s ridge caps and StarterMatch starter strips are among them. GAF gives no algae coverage for its other accessory products.
- Atlas: the Scotchgard Protector algae warranty requires StormMaster or Pro-Cut hip and ridge shingles featuring Scotchgard Protector.
That makes the ridge cap a line item worth reading. A bid can name an algae-resistant shingle and still price a ridge cap from another maker. Ask for the product names, not the word accessories. Our wind ratings guide shows the same pattern: the top level is a system promise, and one missing piece lowers it.
What is not covered by an algae warranty?
- Other growth. Owens Corning says it does not cover other growth such as mold, lichen and green algae. It covers brown-black staining from Gloeocapsa magma.
- The wrong shingle version. Owens Corning says shingles not labeled Algae Resistant have no algae coverage, and CertainTeed limits its algae terms to the AR version.
- Damage from cleaning. Owens Corning excludes damage from power washing and from cleaning solutions that do not follow its algae removal instructions.
- Gutter corrosion. Owens Corning and CertainTeed disclaim damage to aluminum gutters from copper in low-rainfall and salt-fog areas.
- A lapsed base warranty. CertainTeed’s algae coverage is valid only while its main warranty is in force.
A warranty is also a separate thing from your homeowners policy. This guide does not say whether your policy pays for anything on your roof. Read your policy or ask your insurer. Our warranty tiers article explains how the manufacturer and contractor warranties fit together.
What should I ask a roofing contractor about the algae warranty?
Ask for the algae term in writing, with the product names behind it. Then ask every contractor the same questions so the answers line up.
- Which shingle line and color is in the bid, and is it the algae-resistant version? Please write the algae warranty name and the number of years.
- How many of those years are non-prorated?
- Which hip and ridge product is in the bid, and is it the manufacturer’s own algae-resistant product?
- Is the starter strip a match for the shingle line?
- Is the 25-year or 30-year term the one that applies with these exact products, or does a different accessory shorten it?
- Is there any enhanced warranty in the bid that lengthens the non-prorated period, and who registers it, and by when?
- Will I get a copy of the manufacturer’s current warranty for my install date?
A 25-year algae warranty is one of the points worth asking for when you compare bids, next to wind rating, impact rating and the labor and defect warranties. Put the answers on one page. Our roof bid comparison worksheet has room for the warranty line, and our guides on Class 4 impact-resistant shingles and the contract checklist cover two of the others. We do not state prices here because they vary by job.
Where Otter Quotes fits
Otter Quotes creates a written scope of work for your project and sends it to multiple contractors. Contractors who receive the scope can submit bids on that same scope and the same measurements. You compare the bids online, next to reviews and licensing information, and sign online without a salesperson in your home. Subcontractors bid too, so you may be able to work directly with the crew that does the work. We do not work with your insurance company. We are not a contractor, we do not sell upgrades, and we do not offer inspections or assessments. Contractors pay Otter Quotes a fee on the accepted bid.
Frequently asked questions
What causes black streaks on shingles?
Most black streaks are blue-green algae, a cyanobacterium called Gloeocapsa magma. It travels on the wind, needs moisture, and tends to show up on the northern sides of a roof. The manufacturers’ algae warranties cover this discoloration only.
How long is the GAF algae warranty?
GAF’s terms are 10 years for StainGuard, 25 years for StainGuard Plus (including Timberline HDZ), and 30 years for StainGuard Plus PRO (Timberline UHDZ). The 25- and 30-year terms apply only to products sold in packages bearing the matching logo. The non-prorated period is 10 years on the long terms and 1 year on StainGuard.
Does the Owens Corning algae warranty depend on the ridge cap?
Yes. Owens Corning’s August 2026 warranty lists 25 years for Duration Series, Woodcrest, Woodmoor and Oakridge shingles, but only with a qualifying Owens Corning hip and ridge shingle. Without one, the term is 10 years with a 1-year non-prorated period.
What does an algae warranty pay for?
In the GAF, Owens Corning and CertainTeed warranties, the remedy is the cost of cleaning the affected shingles or, at the manufacturer’s option, replacing them. After the non-prorated period the payment is reduced for the years of use, and on Owens Corning it covers shingle cost only, with no labor.
Does Otter Quotes work with my insurance company?
No. We do not work with your insurance company, we do not offer inspections or assessments, and we are not a contractor. Otter Quotes creates a written scope of work for your project and sends it to multiple contractors, who can submit bids on that same scope. Questions about your policy go to your insurer.
Sources
Algae warranty terms change by edition and install date. Figures here were read on October 19, 2026.
- GAF, residential warranty comparison guide: StainGuard 10 years and 1-year non-prorated, StainGuard Plus 25 years, StainGuard Plus PRO 30 years, 10-year non-prorated period, possible 15 years with an enhanced warranty, cleaning or replacement remedy, no algae coverage on other accessories.
- GAF, Advanced Algae Protection page: Gloeocapsa magma, copper microsites, which lines carry 25 and 30 years, StainGuard Plus logo packaging condition.
- GAF Technical Bulletin R-102, Algae Staining on Shingled Roof Surfaces: northern exposures, power washing warning.
- Owens Corning, Standard Product Limited Lifetime Warranty, Pub. No. 10023873-I, August 2026: 25-year AR period, qualifying hip and ridge shingles, drop to 10 years and 1-year non-prorated, remedy and proration example, exclusions, gutter note.
- CertainTeed, Asphalt Shingle 2026 Limited Warranty, for shingles installed January 1 to December 31, 2026: Table 1 algae periods of 30, 25 and 10 years, proration start, AR hip and ridge condition, clean-or-replace remedy, transfer, gutter note.
- Atlas Roofing, Standard Limited Shingle Warranty, Residential (ATL-257316-00 2/26): Lifetime (single-family) and 25-year Scotchgard Protector algae terms, 10-year Premium Protection Period, cleaning-only after it, hip-and-ridge condition, ProLam ARS 10 years, gutter note.
- IKO, US Limited Warranty, Information for Asphalt Shingles (MR1L032): Cambridge 120-month algae resistance period, clean-or-replace in year 1 then a prorated cleaning-only payment, IKO hip and ridge requirement, Cambridge Cool Colors not covered for algae.
- Asphalt Roofing Manufacturers Association, Algae Discoloration: Gloeocapsa magma, airborne spread, warm and humid climates, cleaning cautions.