Roof cleaning has become a science when you have Gloeocapsa magma
Which is classified as a cyno bacteria and you have mold ,mildew and algae infecting tile roofs and growing on surfaces these infectors need to be killed. Pressure cleaning at any pressure will not do.It can be dangerous to the contractor pulling a round a heavy hose filled with pressurized water. And it can have a sever effect on the longevity of the cement joints and the integrity of the tiles themselves. Surface Cleaners should never be used on a tile roof, as they can break tiles from inertia. A 10% solution of sodium hypocloride (pool bleach) alone will not kill these infectors.
There are many ways that have been tested and have be proven to kill these roof tile infectors chemically cleaning has proven to be the best for numerous reasons
With the proper chemical cleaning system, using the proper mixtures of sodium hypo chloride , mild detergents with an algicide and a solution thickener to minimize runoff.
Along with the chemically cleaned tiles these infectors of bacteria,mold and algae a 4 to 5 year window can be achieved before the tiles and shingles will need to be cleaned and some one walking back on a tile roof .
The myth that pool bleach is to strong to use because it will degrade concrete and coated tiles is just that ,a myth .
Once sodium hypo chloride is diluted with water for cleaning it breaks down in less that 18 days . In the environment, chlorine bleach (Sodium Hypochlorite) eventually breaks down into water, oxygen, and table salt (sodium chloride or NaCl) – the same chemicals that are used to create it.
There is nothing more toxic that will break down the integrity of the tile and any manufactured coating than mold mildew and algae growing on for and extended period of time and ultraviolet rays from the sun.
If the ultimate goal is to keen the tile clean and keep people from walking on the roofs as minimally as possible. Chemically cleaning is an answer
Simix Surface Solutions has created a products that can be used to clean and coat any exterior surface that is completely green and the manufacturer will issue a 10 year warranty against mold mildew and algae growth. And it will protect the surfaces from the suns ultraviolet ray damage,that means longer color retention and less degradation.
If the ultimate goal is to keep the tile and shingle roofs clean ,and not have some one on the roof every 2-to 3 years either one of these cleaning process is a winner.