Causes of Ugly Roofing
Limestone didn’t used to be a component of shingles. When the mats used to build shingles were changed from felt paper to fiber- glass, the manufacturers had a problem getting the shingles up to the minimum weight requirement. Someone decided to add pow- dered limestone dust but didn’t realize that it was food for algae. Fortunately, the algae don’t harm the shingles.
Roof shingles are the perfect place for moss and other algae to grow as this part of your home receives the most rainfall and has higher levels of humidity, making conditions perfect for moss to thrive. If there are large trees near the home that shade parts of the roof, moss can grow in abundance as there is a lack of direct sunlight. The accumulation of leaves and other organic debris can also aid in giving moss the nutrients it needs to grow.
Lichens are a fungus, usually of the class Ascomy- cetes, that grow symbiotically with algae, resulting in a composite organism that characteristically forms a crust-like or branching growth on shingle gran- ules. Lichens put out root-like tentacles that pene- trate deep into the shingle’s organic, oil base for nourishment, eventually ruining them by creating dark spots, or pock marks where they grow.