Most homeowners are unaware, that the roofing manufacturers specify exact cleaning methods and chemicals, that may be used on their products, without voiding their warranties.They all say "DO NOT PRESSURE WASH"
Seeing as how the roofing manufacturers not only make the product, but also stand behind it with a warranty, common sense dictates we listen to them.
"We" being you the homeowner and myself and others, who are in the business of cleaning roofs as contractors.
For most of us, our roofing is worth more than our vehicle.
We follow the auto manufacturers instructions with changing the oil etc, to be sure we do not void our warranty and to get all the trouble free years out of our vehicle that is reasonably possible.
If a local mechanic were to try to convince you, not to pay attention to the clear instructions provided by your vehicle's manufacturer, would you listen to him or the manufacturer?
If he told you automotive oil was not the best thing to use in your vehicle, but that a product he made himself or sold, was superior, would you chance causing your warranty to become invalid, by listening to him, instead of the auto manufacturer?
Perhaps he tells you that his product is "GREEN" "ECO-FRIENDLY" "BIO-DEGRADABLE" and that "OIL" can add to polluting the Earth. Will you be swayed from the facts by his sales presentation?
That scenario, is exactly what you would be doing, if you ignore the specific instructions from your roofing manufacturer!
Roof Cleaning was largely an unneeded process throughout much of the United States until the last 20 years or so.
Now, roof stains are infecting much of the country.
Here in Florida, for instance, the stains that appear on a roof are the living organism ( Gloeocapsa Magma algae ) that will gradually reduce the lifespan of the investment you made in your home.
These organisms feed on the limestone filler base in roofing shingles, causing the reflective ceramic granules to loosen and end up in your gutter, or on the ground. As these granules have the limestone filler eaten away you may notice your homes utility bills go up.
Eventually, no longer able to effectively reflect the suns rays away from your home, the air conditioning system, during hot months, will end up working overtime to keep your house cooled. The black coating of algae will also absorb and hold heat to your roofs surface.
In winter months, your heating bill will rise as compromised shingles are less able to retain the heat in your home. An infected roof not only reduces your homes curb-appeal but also it's property value.
Barrel and Flat tiles are also affected by this algae. In the case of tile, the greatest problems are cosmetic, unless it is painted tile, then the algae will eat the paint and get under it's surface.
A roofs life expectancy can be reduced by as much as 50% leading the homeowner to believe roof replacement is their only option.
All these factors contribute to a premature roof replacement, a costly outcome for any homeowner.
To read quotes from a number of roofing manufacturers and have the ability to actually click on the roofing manufacturers links and read those same words on their websites and technical bulletins, please visit my website and click on "Manufacturer Specifics"