Roof moss removal
A lot of people have trouble of varying degrees with moss growing on their roofs, mostly this doesn't cause any leaks but sometimes it does. This is the most effective way to stop leaks, however apart from the obvious dangers of working at height, be careful when walking on the tiles not to break them.
Roof moss treatment - Chemicals to kill moss can be sprayed onto the tiles later if you want to inhibit the re-growth of moss after you are finished.
I hope this guide helps...