Whenever we clean residential properties, including bricks or stones we will always recommend soft washing. Many people will often cause unintended damage to stone or brick through the use of unsuitable pressure settings.

Organic growth thrives in situations where there’s limited sunlight.  So the shady side of your house - here in Texas, think the North side - is prone to moss, lichen and algae growth.  

All organic growth is more likely to become established in damp areas, because they all need moisture to thrive, and if it has been an especially rainy year it could explain why this is the first time you’ve seen it!  Organic growth thrives on porous substances so your bricks or paint layers might also be contributing.