Question: Is moss harmful if left alone. Can moss be harmful if left alone.
answer: Yes Because it can root itself in to the structure and deteriorate your roof. Watch the show life after people, it shows how moss and lykin are the first organisms that start to break down our structures to pave the way for the larger organisms. Also, it retains water which you dont want. Roofs are sloped for water, because you want water off of your roof as fast as possible which is why the steeper roofs last a little longer. Also, it can lift and separate shingles. Some of the more worst case scenarios is that it will root into the structure through the shingles and into the wood. Ive seen it. The only time that you should leave moss on your roof is if you have an old roof which a cleaning would not be good for it and you would be just wasting your money. Just go ahead and put that money towards a new one.