Have you looked at your roof recently? Ever notice on the north face of your home black streaks or splotchy green starburst patches happening up there? This is the natural occurrence of algae and lichen growing on your roof. Algae loves to feast on the limestone found in your asphalt fiberglass shingle. The lichen loves moisture and humidity that’s why you’ll mostly see it occurring on the north face but if you have a shady property it could be anywhere. It is quite an eyesore going on up there. According to GAF a prominent shingle manufacturer the algae is not something to worry about in regards to the integrity of your home’s roof, it just looks bad. However lichen which can end up growing on the algae (also moss and fungus) can cause early deterioration of your roof shingles. The lichen can grow all around the shingle’s granular finish which protects the shingles from the harmful UV rays produced by the sun. The lichen will eventually dislodge the granules from the shingle causing irreparable damage.
Ouch, so it sound like you should clean that stuff off, but how? GAF recommends applying an “anti-algae solution” which according to their recipe is 4 gallons of water, 1 gallon of bleach and 1 cup of tri-sodium phosphate wait approximately 15 minutes and then wash it off. Do not power wash your roof! Problem! The Sodium Tri Phosphate is some pretty nasty stuff and I believe it is not legal for use in New Jersey. I contacted a local company, Truclean, to find out about what my options are. They informed me that in New Jersey you typically find three methods for cleaning your roof; power washing which is not recommended by shingle manufacturers so that doesn’t seem like a very good option. What happens with power washing is the spray is so strong it will take those granules off which we stated earlier protects your roof from the UV. Another method is shampooing, which is basically a giant roof polisher that sprays out chemicals on to your roof and scrubs them in with a water buffing machine. I reached out to GAF to ask them if this was acceptable and again they informed me they do not recommend this method. The last method is “soft wash” which is basically applying a legal solution of chlorine bleach and water to the entire roof with a very gentle wash. The next step is totally natural which is just wait for the rain to wash it away. This way there is no worry of the granules on the roof being damaged. This application is the ARMA (Asphalt Roofing Manufacturers Association) approved method for cleaning your roof. According to Truclean, the Algae removal will be noticeable immediately, however, the lichen will take time to restore the roof to its original color after cleaning and could take up to a few months.
In addition to the unsightliness of your roof, if you let it go, your homeowner’s insurance could send you a notice of cancellation if you refuse to clean it! So get out there and take a look and see what’s happening on the outside of your home.