Moss and algae tend to grow in damp shaded areas and can cause damage to your roof if left untreated. If you allow large amounts of moss to grow over your roof these patches can become damp and end up rotting the materials below.
If moss removal is something you arenโt taking seriously it can lead to water becoming trapped by moss pools in gaps between your roof tiles.
If you notice this is happening ideally you want to catch it before the moss pool water freezes and thaws as this can lead to tiles being pushed apart causing further damage to your roof.