When you live in Texas, it is not uncommon to see roof discoloration. There are many factors that contribute to staining roofs and while most stains are cosmetic, some can be more damaging than you may expect. Here is a quick guide to roof discoloration and the reasons they are changing their color.
Algae Stains & Clean Streaks
Algae stains are probably the most common type of roof discoloration. Algea vary in color from black to dark green/brown. There are many different types of algae that have been found on roofs and all are typically in humid climates. Algae stains usually form in areas of high shade and moist spots. Black streaks that spread across different shingles identify the discoloration as algae. This can be easily washed off with an anti-algae agent mixed with water. Be sure not to power wash or aggressively scrub the roof as this can cause extra roof wear. Clean streaks can be found trailing from certain protrusions of your roof such as aluminum vent fixtures. The aluminum salts can slowly wash down the roof preventing growth of algae in streaks where algae usually tends to grow.
This is often confused with algae stains, however, you will notice that the stains will seem to originate from specific shingles and not in generic areas. This roof discoloration comes from manufacturing defects where the shingles have not been properly cured and the pigment of the asphalt leeches out of the shingles, causing dark streaks on your roof.
Debris stains can vary in color from brown to black and can be attributed from both organic and inorganic matter. Brown to black stains found in the shady areas under trees are caused from both small and large particles falling off the tree and essentially dyeing the color of your shingles. This type of stain can also be found where debris tends to collect on your roof. Grey to black stains will often be found around chimneys and can be attributed to soot and ash. Gently washing with soap and water can help with some of these stains.