The growth of Algae Mosses & Lichens on Tiled Roofs

Dirt from rainwater is filtered by the rough surface on roof tiles and is the principle cause of moss and lichen growth.

In addition decaying matter (such as dead leaves) falls on the roof and a proportion gets trapped. Moss spores, seeds and lichens are blown on the roof, or get carried there by birds and take root in the dirt.

The rough surface on concrete tiles, which have a sanded or granule facing, are the first to attract moss growth. It tends to flourish when trees are nearby and in shady, damp conditions.

North facing slopes which remain damper longer, attract the highest levels of moss and lichens.