Fortunately for us the very nice roofing man we called to investigate the problem very quickly discovered what the problem was and fixed it without even charging us.
Moss on roof tiles is it a problem.
Shaded areas exposed to frequent damp cool weather will quickly encourage moss to grow on your roof.
Avoid any aggressive cleaning methods that might damage the roof surface.
Moss absorbs and retains water.
Roof moss prevention if the above sounds like too much of a hassle which honestly it likely does then know that the most effective method is to prevent the problem of moss on your roof in the first place.
If you remove moss from the roof then you will reduce the possibility of tiles suffering from winter cracks.
The presence or absence of sunlight dictates the amount of moss or algae growth.
The presence of algae on the roof is an indicator that this roof area is in a shaded spot where you may want to be alert for development of moss or other roof problems but the level of damage from algae is probably low even less than that caused by lichens.
Ultimately moss growth on a roof can result in costly repairs and can also reduce the lifespan of your roof.
We had a problem where in very heavy rain the moss build up in the valley was causing water to back up and go under the tile above.