What are algae-resistant roof shingles?
How the protection works
The black streaks on Georgia roofs come from airborne algae that settle on damp shingles. Copper is toxic to that algae. Manufacturers blend a share of copper-containing granules among the colored ones, and each rain carries a little copper across the shingle surface. Because the copper slowly depletes, the protection is strongest in the early years and fades over the life of the roof.
Names you will see
Each manufacturer brands its own version, such as StainGuard on GAF shingles, StreakGuard on Owens Corning shingles and StreakFighter on CertainTeed shingles. The branding differs, but the copper granule idea is the same. GAF, for example, ties its longest algae coverage to packages that carry the matching logo, so look for it on the wrapper.
What the algae warranty covers
- Discoloration from blue-green algae, for a set number of years.
- Usually not moss, lichen, dirt, pollen or rust stains.
- Terms and remedies vary, so read the manufacturer's written warranty rather than the brochure.
Worth it in Georgia?
Yes, and usually you do not have to choose it: algae resistance is standard on most architectural lines sold in the Southeast. It matters most on shaded, humid lots and on lighter colors, where streaks show more. It cannot be added to an existing roof, and it will not stop moss under heavy shade, so trimming trees still matters. For cleaning an older streaked roof, see black streaks and algae on roofs, and for color choices, see the best shingle colors for Georgia heat.