Lichen

Warm temperatures, dust, and rainfall can create an environment for lichens to flourish. Over time the root structures of lichen may infiltrate a painted surface and cause permanent damage.

Lichen growths retain moisture and, therefore, increase the time of wetness. They are fed by nutrients in the atmosphere and tend to occur more commonly in moist and unpolluted environments. Where lichen growth is present, it should be removed. See Maintenance.

Physical removal is difficult to achieve completely, and recolonisation is usually rapid. Chemical treatment is recommended. New Zealand Steel publishes a formula for batching a 2% sodium Hypochlorite solution to be used for this.

Lichen on a Metal Roof
 

Lichen on a metal roof

 

Permanent Damage from Lichen Growth

Permanent Damage from Lichen

Lichen growth can cause permanent damage if not treated promptly