Algae-resistant (AR) shingles are asphalt shingles whose surface granules include a percentage of copper-bearing ones. Every time it rains, the copper releases a trace of ions that wash down the roof, poisoning the blue-green algae (Gloeocapsa magma) responsible for the black streaking common on shaded roofs — and making the whole surface less friendly to biological growth. It's the same chemistry as the copper and zinc strips roofers install at ridges, built into the shingle itself and spread across the entire plane.
Black streaks or moss taking over your roof? We treat it — and can reroof with algae-resistant shingles. Serving Roseburg, Riddle & all of Douglas County.
Why they matter in the Umpqua Valley
With 130-plus rain days a year and heavy tree canopy, Douglas County roofs are prime habitat for algae and its uglier cousin, moss. AR granules keep a roof looking clean for years longer, and while they won't make a roof moss-proof, they slow moss establishment on the north and east slopes where it starts. If you're already replacing a roof, this is close to a free win: AR granules come standard in most quality architectural shingle lines, including the Owens Corning products we install. Our moss prevention guide explains where AR shingles fit in the bigger picture.
Without them, what it costs you
Black streaking is mostly cosmetic — but it drags down curb appeal and resale photos, and the cleaning cycle to keep a non-AR roof presentable adds up over 20 years. More importantly, a roof that stays biologically cleaner sheds water better and holds its granules longer. If your current roof is already streaked or mossy, don't pressure wash it; our roof cleaning and moss removal service handles it without destroying the granule layer, and at replacement time you can build the resistance in.
Do AR shingles cost more?
Barely, if at all — in most quality architectural lines the AR treatment is standard rather than an upcharge. Confirm the algae-resistance warranty term when comparing products; longer terms mean a higher copper content.
Related terms
Granules · Architectural shingle · Three-tab shingle · Ridge cap · Valley