What lichen actually is
Lichen is a partnership between a fungus and algae. It forms those crusty grey, green, yellow or orange patches you see on roofs, fences and rocks. It grows slowly, but it’s tough and it holds on tight.
How it affects your roof
Lichen anchors itself into tiny pits in the roof surface and holds moisture there. On concrete tiles, that can gradually wear away the surface and the coating. On metal roofs, it can break down the paint or coating over time.
As patches grow and break off, they also end up in your gutters and downpipes, which is one reason gutters on lichen-covered roofs block more often.
Why scraping and blasting don’t work
Pressure cleaning can remove the visible lichen, but it often leaves the roots behind and it grows back. High pressure can also crack tiles, lift flashings and strip the coating you’re trying to protect.
The safe way to remove it
A soft wash applies a cleaning solution at low pressure that kills lichen at the root. Once it’s dead, it releases its grip and weathers away — some comes off on the day, and any stubborn patches fade over the following weeks as rain washes them off.
Because the growth is killed rather than just knocked off, the roof stays clean much longer.