Your Roof's Potential Problems
Stage 1: Invisible Algae
Once your new 30-year roof is installed, spores can travel from nearby algae growth and begin infesting your roof. The algae starts growing and can't be seen for many years.
Stage 2: Black Stains & Streaks
Around 5-10 years into the life of the roof, you will begin to notice black stains and streaks, especially on the shaded areas of the roof. The algae form the black covering to protect themselves from the sunlight. The algae feed on the lime deposits present in the shingles.
Stage 3: Lichen & Moss Growth
Between years 10-15 of the roof, the black streaks have progressed to grow lichen or moss. The shingles have been degraded and the algae can reduce the life of the roof up to 50% In any case you are not likely to get the full 30-year life from your roof.