How Moss and Lichen Damage Tile and Colorbond Roofs
Updated: Sep 29
The dark roof you see from the street in St George is rarely just dirt. Shaded concrete tiles grow algae and moss. Colorbond grows lichen. Both keep the surface wetter than it should be.
Three growths, three problems
Algae: the green film on shaded tiles, common on the south side and under trees.
Moss: thicker growth that stays wet and sits in the tile lap.
Lichen: the black or grey crust on colourbond and on older tiles.
Washing the growth off does not repair a cracked tile or a failed colourbond coating. It stops the moisture sitting there and lets you see what the roof actually needs. The choice between soft wash and pressure is covered in our soft wash guide.
Spotless Pressure Kleen is based at 47 Bundara Street, Beverly Hills, with no shopfront. Call 0450 588 489.
How does moss damage a tile roof?
Moss stays wet after rain and holds that water against the tile and in the lap. Over time the tile stays damp, the surface breaks down, and water has an easier path toward the ceiling.
Is the black film on colourbond lichen or dirt?
Black spotting on colourbond is often lichen, not ordinary dust. Left for years it stains the coating. Soft washing lifts it. A hard blast can mark the finish, so we do not treat colourbond like a concrete driveway.