Roof lichen, or more regularly recognized roof moss or algae, is a very common sight on many shingled or tiles roofs. Whilst appearing more like a cosmetic problem, the roof lichen can cause serious harm to your roof. It holds moisture and can cause roofs to bend and bow inward and eventually collapse if left untreated. Lichens are not as problematic as moss or algae but it can lead to further issues.
Treatment of Lichens, Moss, and Algae
Metal or copper stripes around the top of your roof can help to kill off and prevent lichen from returning. Homes that have metal at the very tops of their roofs seem to suffer less from lichens and the main reason for this is that the metallic composition, when mixed with rainwater seems to cause a chemical reaction that damages the lichens and cleans the roof. It is also suitable for reinforcing an older roof.
It is not recommended that you stand on your roof and scrape or wash them off. That is unless you are certain that your roof is solid, steady and structurally sound enough to hold your weight. Dry scraping can be done and you can also use chemical cleaners and killers to remove the lichen from the roof. However, do bear in mind that you may also be causing chemical harm to the roof shingles. If your roof is completely or more or less completely covered in moss, algae or lichens, it is probably better to have your whole house re-roofed. You can purchase safer removal chemicals which are specifically for asphalt roofs and will kill off the lichens.
Keeping the Lichens and Moss Away
Houses that have roofs in very shaded areas are more prone to lichens, algae and moss growth. If you live in a heavily wooded area or if your home is surrounded by many tall trees, your roof may not be getting enough direct sunshine to dry out the moisture in the algae or moss. Trim back the branches of heavily over-hanging trees to let more sunlight on to your roof. Stone roofs prove far more difficult to remove lichens from.
You can opt to power wash your roof with the caveat that you take care not to damage the shingles. If they are older and more fragile, you may cause a leak if one of the shingles breaks or falls away. If you opt to power wash your roof and remove the lichens or moss, you should use the proper equipment and a mild detergent, rather than a heavy abrasive cleaner. You can then brush the loosened lichen and moss from the roof, safely. If you are still uncertain, it is better to call a roofing contractor who has the professional ability and equipment to carry out the job for you. If you opt for a new roof, most new shingles now come with inbuilt chemicals to help kill and prevent roof lichens, algae and moss from growing.