You may have heard all the new fad "GO GREEN" "Biofoam" "Bio Degradable" "Eco-Friendly" roof cleaning pitches that have cropped up recently. They try to convince unknowing homeowners that chlorine bleach should not be used on roofing to clean them. With most every new hype product, in the end, they will pressure wash the roof!
The STORY will be "We turn the pressure way down" Which simply means-if they actually do? That they have to hold the high pressure spray tip closer to your roof! It takes a lot of pressure to remove black algae from a roof!
The manufacturers of roofing know better and specify that chlorine bleach be used. They also specify that a pressure washer, and similar pressure methods and brushes, not be used.
So, we at Chuck Bergman Pressure Washing - while starting out as pressure washers only, in 1989, started cleaning roofs with the manufacturers specified method and cleaning agents since 1991.
Now, here are the facts from The Roofing Manufacturers themselves. It's your warranty. Don't allow a pressure washing machine, etc to void it!
Pressure washing can blast the discolorations, along with your roofs granules etc, from your roof, and that may cause the manufacturer roofing warranties to become void.
As with any purchase, it's best to follow the maintenance as specified by it's manufacturer.
Below are what these roofing manufacturers have to say.
From GAF Roofing Manufacturers about black algae removal:
Below is a partial "cut and paste" excerpt from GAF on how to clean a roof:
"If a new roof is not an option, GAF recommends cleaning the roof with a special mixture. That mixture is: 4 gallons of water, 1 gallon of bleach and 1 cup of TSP" "What NOT To Do! Do not power wash the shingles to clean the shingles. Some roof cleaning companies offer this service. However, it is not recommended."
From ARMA roofing manufacturers Association-how to clean roofing.
Below is a partial excerpt cut and pasted below from ARMA:
"Algae discolorations to remove from roofing surfaces, applying a solution of chlorine bleach, trisodium phosphate, and water. Solutions for these ingredients depend on the amount of discoloration. Solutions range to one cup TSP and 2.5 gallons each of bleach and water. First, gently disperse this solution on the roofing surface. Avoid scrubbing the surface, as this friction may loosen and remove granules. Caution! High pressure washing systems for algae removal should not be used."
Owens Corning Roofing manufacturers says the same thing:
"USE CHLORINE and TSP" "DO NOT USE A PRESSURE WASHER"