For quite some time now I have been concerned with
Removing Moss / Fungus / Mildew Discoloration from Roofs

In doing so one must consider foliage on the ground that can be affected.

Used correctly both Oxydizing and Chlorine Bleaching Agents will work.
The process is not immediate, but once done, precautions
can be taken to prevent reoccurence.

Prior to application of any chemical agent on roof moss,the heavy bulk
should be removed with a stiff nylon brush
and plants and foliage that may catch an overspray
should be soaked with water prior to the chemical application
and after rinsing.

Pressure washing should be avoided as the intense pressure will
remove the granules from the roof shingles.

TriSodium Phosphate mixed with chlorine bleach and water
is one mixture that works.

Powdered Oxalic Acid mixed with water works.

A solution sold by a company named Zinsser called JO Max
mixed with bleach and water is for sale in paint stores.
One formula is recommended for siding and another for roofs.

No matter what is used, one must be patient
results are not instant
as the attempt should be to use as little of the chemical as possible
as to avoid damage to shrubs and foliage.

I will be providing this and other services as weather permits.

Check out my Home Services Site