Roofing Manufacturer Cleaning Info. Partial cuts and pastes from their websites. This is from the ARMA roofing manufacturer asso. Solutions range from one cup TSP, one gallon bleach and five gallons of water, to one cup TSP and 2.5 gallons each of bleach and water. First, gently disperse this solution on the roofing surface. Caution! High pressure washing systems for algae removal should not be used. ----------------------------------------------------------------------------------------------------------- Partial cut and paste from GAF Roofing Manufacturers website below. 'GAF recommends cleaning the roof with a special mixture. That mixture is:4 gallons of water, 1 gallon of bleach and 1 cup ofTSP (Tri-Sodium Phosphate-or acceptable phosphate-freesubstitute) found at many home centers. Apply this mixture' "What NOT To Do! Do not power wash" ---------------------------------------------------------------------------------------------------------------------------- Partial cut and paste from Owens Corning Roofing Manufacturer: "Algae growth causes a dark discoloration on roofs. The algae is usually brown to black in color which results in a streaked, dirty looking rooftop. RECOMMENDATIONS by spraying a diluted solution of chlorine bleach, trisodium phosphate, and water onto the roof. Solutions range from one cup TSP, one gallon bleach and four gallons of water, to one cup TSP and 2.5 gallons each of bleach and water. Do not scrub. -------------------------------------------------------------------------------------------------------------------------------------- ARMA TECH BULLETING CUT AND PASTE After Cleaning Coatings "Field Coatings" "ARMA strongly advises caution when considering the application of any type of field applied coating over installed asphalt shingles. There are many types and formulations of roof coatings so it is important to always consult the shingle manufacturer before proceeding with any type of coating. Be aware that some asphalt shingle manufacturers specifically disallow field coating of their manufactured shingles. Additionally, state or local building codes may not approve this practice as the field applied coatings will drastically change the aesthetics of the roof and may change the performance characteristics of the roof assembly. Problems reported after asphalt shingle roofs have been field coated include unsightly curling and/or cupping of the shingles which may lead to premature failure and leaks. In addition, non-permeable roof coatings may create a vapor retarding layer; if this occurs, it increases the possibility of rotting of the roof deck caused by moisture accumulation in the attic space. It has been suggested by some that the use of field applied coatings over existing asphalt shingles will produce overriding benefits to the home owner — such as longer roof life, energy-use reduction (solar reflectant versions), or remediation of small roof leaks. There is little or no available documentation showing the extent to which the field coating of asphalt shingles provides any of these benefits, but the risks and concerns mentioned above remain very real. When considering coating of installed asphalt roof shingles, be sure to: *Obtain approval from the asphalt shingle manufacturer before proceeding with a specific roof coating. *Check with the local building department to determine whether this application is allowed" THE ACTUAL LINKS TO THESE MANUFACTURERS, WHERE I CUT THE TEXT FROM ARE HERE- http://www.bergmanpressurewashing.com/Manufacturer_Specifics.html