Roof Cleaning - Nothing But the Facts Please (Part One)

 

Limestone was introduced to the shingle manufacturing process when oil prices started to escalate some years ago. Asphalt impregnated material was used in the shingles to add weight and substance to your shingle. To save on rising petroleum cost, and ultimately shingle costs, the manufactures substituted limestone in preference to some of the asphalt material.   Limestone being relatively low-cost and dense was a perfect substitute. However, limestone also feeds Gloeocapsa Magma. Feeding away from the warm temperatures, high humidity and limestone inside shingles for food, if left unattended, the algae can cause some significant damage over time.  

 

At first this algae is more of eyesore than anything, and may be easily removed. Left on the top, it will keep dispersing until it covers the complete roof. At this point the idea becomes food for mildew and lichens this also is where the real trouble starts. Be careful! Many times a roofer are going to be called in to inspect the roof and a few roofers will tell the homeowner they need a new roof and perhaps, that may be consequently. But, too many times just a cleaning will suffice saving the homeowner thousands of dollars.

 

However, left unattended, the mildew will build up over time until you will find there's substantial layer of which will breed mildew. The mildew builds up to a point that moss will quickly grow. Moss can the end up in Lichens and Lichens have little tentacles that grow down into the shingle. Once this tentacles get established, they are very challenging to remove and in the operation, some of the shingle grit are going to be dislodged leaving pits or holes inside shingles.

 

So it is recommended to remove that stains before it obtains that bad. The best time to clean the roof is the warmer months of course, if the algae covers 30% to 40% in the north roof. By this time it is likely that is has spread to the areas of the roof but will only be a matter of your energy before it begins to show. The longer you wait, the harder and less affordable to remove.
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As you might already take note, chemical roof cleaning is a superior alternative to roof power washing. There are many roof cleaning products and solutions on the market these days, all claiming being superior, and all claiming that their's may be the safest and most effective, but it's important to keep in mind that these are companies which were just trying to generate a buck and will say almost anything to sell their product.

In my considerable experience, there's only 1 clean a roof the right way, and that's with a sodium hypochlorite-based solution. Sodium hypochlorite could be the active ingredient in bleach and chlorine, and when used on a roof at the right ratios is quite simply the safest, most effective way to clean a roof. It is the recommended method for cleansing roofs by ARMA (your Asphalt Roofing Manufacturers Connection) and GAF (North America's largest shingle producer).

ARMA recommends a wide selection of bleach, water, and TSP (which can be found in paint stores), but be careful with the TSP on painted surfaces as it can remove the gloss in high dosages. Detailed information on roof cleaners can be found at main website