The Roof Cleaning Institute Of America Training & Certification Forum
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Congratulations for finding this page on your quest for a cleaner roof. I always commend those who do their homework in finding the proper contractor who properly treats asphalt shingle roofs for black roofing stains, mold, and lichens. Let us take a moment to discuss exactly what’s growing on your roof.

What are those ugly stains on my roof?

Many theories have been tossed around pertaining to roofing stains. Some creative theories include homeowners who think that jet planes are dumping fuel before they land. The simple fact is black roofing stains are caused by an organism called gleocapsa magma that literally feeds on the limestone in the roofing shingle. This organism is a bacterium that forms a black UV repellent outer husk that allows it to withstand even the harshest of elements. Each time it rains it pulls the growth downward which gives a streaking appearance.

Roofing manufacturers started adding limestone to shingles back in the late 70’s because it added weight to the shingle. Adding limestone, which is an organic material, allowed this new organism to spawn in the hot and humid Florida/Caribbean region. It took many years before the organism made its way to the Midwest, Northeast, and the West Coast of the US. This is why many people can have a roof that is 20 to 30 years old, yet have only started noticing stains within the last few years. Once these stains appear moss and lichens are soon to follow. These organisms are very contagious and can be spread through spores, birds and squirrels. This is why many homes in the same area can all possess some form of roofing stains.

Which roof cleaning treatment is the right one for me?

We know it can get confusing with all of the conflicting information on the internet pertaining to roof cleaning. We also understand that your roof has become an eyesore and the problem seems to only be getting worse. Let’s start by approaching the stain like “pest control” rather than a cleaning. Like any other pest control situation our goal is to remove the pest while leaving every part of the host, or in this case the roof, unaffected by the treatment. All growths on a shingle roof develop a root system, like a plant. It is important to treat the growth at the root source to insure a 100% kill ratio. In doing so will insure a clean and spot-free roof for an extended period of time.

Asphalt shingle roofs are composed of two main parts: The first part is the underlying membrane and the second parts are the silicone granules which gives the roof its color and protects the membrane from weather and damaging UV. Without these granules the membrane would succumb to the elements and will dry out, crack, and split. These granules can become dislodged over time, even by rain. Even newer roofs are subject to some granule loss. This is why shingle manufacturers like GAF or ARMA strongly advises against using any type of pressure washing devices on an asphalt shingle roof. Roof cleaning devices that use pressure can wash away large amounts of roofing granules and drastically reduce the life of a roof.

If you buy or sell a home a highly skilled home inspector can determine how many years of life are left on a roof before it needs replacement. To determine this they measure the granule content on the shingle. If the granules are thinned out and sparse, a new roof can be a short time away. Consider these facts when determining the proper roof cleaning contractor for your project. Roof cleaners who use certified non-pressure cleaning practices understand the science of treating the stain like a “pest”. Using the proper roof cleaning detergents applied at 60 psi or under (equal to less pressure than a typical garden hose) will kill the growth at the root source and insure the growth will not return within a specified period. Ask your contractor about the warranties he/she may offer since they may vary according to your region and climate.

Why should I be concerned about roof stains?

Roof Stains are growths that are literally feeding on your roof like an “all you can eat” buffet. The longer they are allowed to grow and fester the sooner the roof will deteriorate and need replacement. They will never go away on their own. They will always grow regardless of cold, hot or dry weather. A roof is most likely the most expensive part of any home. It would make sound economic sense to maintain a roofs appearance and function ability by keeping it free of roof-eating growths.

Now is the time to take some action before permanent damage occurs. On this site you will find a list of Certified Roof Cleaning Specialists, who are fully trained, insured, and certified to RCIA standards. They are the leaders in the roof cleaning industry. Call one of our professionals in your area for a free estimate and demo.