If your building has been attacked by Moss mildew lichens or any other organic growth. I would advise you to go down the soft wash route especially on roughcast and K Rend er type surfaces
Soft washing as as it says a more gentle way to clean rather than pressure washing which involves quoting the building affected area with a biocide which is agitated then left for a short period of time then runs off with a soft wash so if your property suffers from