Most commonly found on west and north facing roof surfaces, moss, lichen and algae grow well in highly shaded areas where sunlight exposure is minimal. After a heavy rain, the west and north facing roof areas don’t dry as quickly as other areas of your roof do that receive more sunlight, and provide a prime breeding ground for moss, algae and lichen growth. Algae is an airborne bacteria, which started in the south about 25 years ago. Left untreated, these growths will hold more moisture, resulting in more damage to all roofing material, algae is the #1 reason for pre-mature roof failure, and can reduce the life expectancy of your shingles by 50%. Most homeowners aren’t aware this algae also voids most manufacturer warranties. Over the years, we have encountered roofs only 15 years of age which were so severely damaged from algae, a whole replacement was necessary.