Algae, Fungus, and Lichen Damage

Does Algae, Fungus, or Lichen damage a roof? Algae, fungus, and lichen on a roof is unsightly, and up until now, were believed to have no long term effects on an asphalt roofs. Recent studies have shown fungus, algae, and lichen may affect the overall performance of an asphalt shingle. The fungus and lichen require an organic based food source to survive. The asphalt in the shingle provides the nourishment for the fungus and lichen to flourish. The fungus and lichen can grow at a rapid rate, completely covering a roof slope in some cases. The fungus secretes enzymes into the asphalt which begin to digest the material at the base of the granule surface. The lichen has small roots that embed down underneath the granule surface to provide nourishment for the infestation. As the lichen blooms die, they pull away the granule surface which exposes small areas of asphalt. The open areas of asphalt are RESTRICTED to the area of lichen growth only. The algae requires an inorganic material to feed upon. Shingle manufacturers sometimes incorporate limestone (dolomite) into the manufacturing process, a specific food source for the algae. Algae are the least harmful of these three infestations.

Algae damage on roofs Lichen damage on roofs