Those black streaks aren’t dirt.
They’re alive, they’re eating your shingles, and StainGuard Plus is built to stop them before they make a roof look ten years older.
StainGuard Plus is how GAF fights back: time-release capsules built into the shingle that keep releasing copper long after older algae-resistant granules give out. It comes backed by a 25-year algae protection limited warranty. GAF explains the technology here.
One roof streaks. One doesn’t.
The difference is what’s built into the granules on day one.
How a clean roof turns black
Blue-green algae is in more than 80% of North American homes, according to GAF. Here’s how it gets from the air to your roof.
It blows in
Algae spores ride the wind and hitch rides on birds and squirrels. Once one roof on a street has it, the neighbors usually follow.
It settles where it’s damp
North-facing slopes and roofs under shade trees stay wet longest after rain and dew. That is where colonies take hold first.
It feeds on the shingle
The limestone filler that makes shingles fire resistant is also food for blue-green algae, known as Gloeocapsa magma.
It builds a dark shell
To shield itself from the sun, the algae grows a dark outer coating. That coating is the black you see.
Rain draws the streaks
Every storm carries the dark growth down the slope, which is why it shows up as streaks instead of spots.
A coating wears off. A capsule keeps working.
Most algae-resistant shingles rely on a copper layer on the outside of the granule. StainGuard Plus puts the copper inside.
Traditional algae-resistant granules
The copper sits in a coating on the surface of the granule and washes onto the roof when it gets wet. As the roof ages, that coating thins and the granules release less copper, so protection fades right when the roof is old enough for algae to take over.
Copper fades as the coating wearsStainGuard Plus time-release capsules
Specially engineered capsules infused with thousands of copper microsites are blended into the granules. They release copper steadily, year after year, instead of all at once. GAF made it standard on Timberline HDZ in 2022, along with matching ridge cap and starter shingles.
Copper microsites release over time
Before you grab a pressure washer
Skip the pressure washer
High pressure blasts the protective granules off the shingle and can drive water up under the laps. The streaks come back, and the roof ages faster than it did before.
What actually helps
A low-pressure wash with a roof-safe cleaner kills the algae without stripping granules. It buys time, but without protection built into the shingle, the black usually returns within a few seasons.
When to think about a new roof
If the roof is near the end of its life anyway, putting the cleaning money toward new shingles with algae protection solves the problem for decades instead of a few summers.
25 years of algae protection, in writing
Coverage applies to qualifying shingles sold in logo-marked packaging, listed below by product line.
On top of the GAF lifetime limited warranty on shingles and qualifying accessories.
- Timberline
- Timberline HDZ, Timberline AS II, Timberline HDZ RS
- Designer
- Grand Sequoia, Grand Sequoia AS, Grand Sequoia RS, Camelot II, Slateline, Woodland
- Ridge cap
- Seal-A-Ridge, Seal-A-Ridge AS, TimberCrest, TimberTex, Z Ridge
- Starter
- StarterMatch
The video, the brochure, the fine print
A short GAF video on the warranty, plus the documents behind it.
Algae protection, answered
What homeowners ask us most about black streaks, algae and how long the protection lasts.
What is StainGuard Plus?
StainGuard Plus is GAF's time-release algae protection. Capsules infused with thousands of copper microsites are built into the granules and release copper steadily over time to keep blue-green algae from taking hold.
How long does the algae warranty last?
Shingles sold in StainGuard Plus packaging carry a 25-year algae protection limited warranty against blue-green algae discoloration. Timberline UHDZ carries the 30-year StainGuard Plus PRO warranty.
Can it clean a roof that already has streaks?
No. It is built into new shingles to keep streaks from forming. If your roof is already streaked, we can tell you whether a cleaning or a new roof makes more sense.
Why do black streaks show up on the north side first?
North-facing slopes get the least sun, so they stay damp the longest after rain and morning dew. Algae needs that moisture to grow.
Does algae damage the roof?
The streaks are mostly cosmetic at first, but a dark roof absorbs more heat and looks years older than it is. Most homeowners notice it hurts curb appeal long before anything else.
How do I know if my shingles have it?
Look for the StainGuard Plus logo on the bundle wrappers or your warranty paperwork, or call (937) 833-5136. Michelle answers 24/7 and can schedule an inspection.
Streaks on your roof, or want to keep them off?
We’ll inspect it and show you what Timberline HDZ looks like on your home. See our roof replacement process.
