Moss, lichen and algae will stick to your roof tiles, making your roof looking discoloured and dirty looking and like any other plant it will grow.
This will cause the tiles to become porous, and potentially succumb to frost damage in the winter.
Freezing water causes expansion which leads to the porous tile being damaged over time and eventually cracking
Moss between and under the tiles will also expand when frozen, causing movement.
Weakened tiles are also brittle, so movement can cause them to fracture quite easily causing potential leaks.
With a heavy downpour of rain, moss growing on the roof can dislodge falling into your guttering, restricting the flow of water and blocking down pipes and drains.
Rain water from overflowing gutters can get into the eaves causing damp and mold, and the soffits can also rot.
Your roof is the most important part of your home to maintain because it’s most exposes to the elements.
If you want to keep your roof in good order, then keeping it clean is essential.