While lichens don't damage the structure of roof tiles, they can stain the surface of the roof as well as trap moisture. Moisture increases the chance of mold growth, which can damage the roof tiles. Several natural remedies can kill the lichens and restore the look of your roof tiles.
The force of water removes surface lichens without any added chemicals, but plain water won't kill the lichens or remove any lingering stains. These discolorations will last until you remove them. After rinsing surface lichens off the tiles with the water, use one of the other natural remedies to remove any lingering growth and stains.
White vinegar is a pungent, versatile liquid that naturally cuts through grease, removes odors and kills fungus and lichens. Natural and non-toxic, vinegar safely kills problem growth without filling your environment with toxic chemicals. Mix 2 cups of vinegar with a gallon of lukewarm water. Dip a brush broom in the diluted vinegar and scrub lichens off the roof tiles.
Because it contains sodium percarbonate, oxygen bleach can be used to remove lichens instead of harsh chemicals. Unlike chlorine bleach, which can damage surfaces, oxygen bleach won't discolor tile roofs. In addition, it's safe for use on asphalt as well as other roofing material. Before using oxygen bleach, dissolve it in water at a rate of 1 cup of bleach to 1 gallon of water.
When cleaning tiles roofs, take necessary safety precautions to prevent hazards. Don't attempt to clean a roof if you have inner ear or balance problems. In addition, wear a pair of shoes with good tread. Only use a steady ladder, and have someone hold it steady as you climb up it and onto the roof.