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ALGAE GROWTH
 CAUSES
- Algae growth causes a dark discoloration on roofs. The algae is usually
brown to black in color which results in a streaked, dirty looking
rooftop. It can be mistaken for soot, dirt or tree droppings, which
typically produce only localized discoloration. It's caused by the
growth of air-borne algae which deposits on your roof. The good news is
that algae growth does not affect the service life of your roofing
material. It occurs most often in warm, humid climates such as the
Southeast (where algae-resistant shingles are available).
RECOMMENDATIONS
- Discoloration of roofs caused by fungus or algae is difficult to remove,
but may be lightened by spraying a diluted solution of chlorine bleach,
trisodium phosphate, and water onto the roof. Solutions range from one
cup TSP, one gallon bleach and four gallons of water, to one cup TSP and
2.5 gallons each of bleach and water. This solution can then be rinsed
from the roof in 10 to 15 minutes. Do not scrub. Scrubbing will loosen
and remove granules. After spraying be sure to thoroughly flush the roof
and the greenery around the home (grass, bushes and shrubs) with water.
The effectiveness of this type of cleaning may only be temporary, and
the discoloration may recur. High pressure washing is not recommended
due to the possibility of removing granules, thereby shortening the life
of the Roofing System.
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