Black roof stains are caused by airborne algae. The stains will not go away over time, they will darken and spread. Roof stains can be removed with our unique, no-pressure washing process. Our non-caustic cleaner is environmentally friendly and gently dissolves away stains, grime and layers of seasonal pollen. Prices are reasonable starting at 15 cents per square foot of area cleaned. Our process can also remove green algae stains on your house siding! Call or email us today for a free estimate!