Algae is often mistaken for roof mold, according to the Asphalt Roofing Manufacturers Association. Algae on the roof is not nearly as problematic as mold, though. While unsightly, algae on rooftops does not present a health hazard and it is unlikely to damage your roof, although it may decrease the effectiveness of reflective or “cool” roofs. Mold, on the other hand, is known to cause or contribute to numerous health problems, some of them quite serious. It can also cause significant damage to your roof and to other parts of your home, as well.
While algae on a pond often looks green in color, when it is found on a rooftop it frequently appears to be very dark green or black in color. It looks very much like many types of mold, including stachybotrys chartarum, sometimes referred to as black mold or toxic mold. A mold removal professional or even a roofing contractor may be able to offer you a professional opinion as to which one is growing on your roof, but it may be difficult or impossible to know for sure unless you test your roof for mold.
Is it necessary to determine whether you're dealing with mold or algae? Maybe, maybe not. Many mold removal products will effectively kill and remove both mold and algae. However, it is very difficult to remove mold from some materials, including wood, so special techniques may be needed, depending on the type of roof you have and the extent of the mold growth. We suggest consulting with a roof cleaning professional about whether or not it's necessary to test your roof to determine whether or not you're dealing with algae or mold.
You can't always prevent mold from starting to grow on your roof, but there are things you can do to minimize the damage it can do to your home.
There are algae-resistant shingles available, made with copper or zinc. These are not mold-resistant, however.
The best way to remove mold from a roof is going to depend on the type of roof you have and on the extent of the mold. Using the wrong type of equipment can end up damaging your roof instead of cleaning it. Of course, using the wrong equipment or mold removal product can also result in mold remaining on your roof.
Removing mold from roofs is dangerous work, both because it involves climbing around on your roof and because it exposes you to potentially harmful mold spores, so we recommend hiring a professional who will have all the necessary safety gear as well as know the best way to clean your type of roof without damaging it.
Note that it may be impossible to adequately remove mold from some types of roofs. If you have wood shingles or shakes, for instance, they may need to be removed and replaced. An experienced professional can advise you and will know if there is a way to save your wood shingles.
If you need mold removed from your roof, we recommend requesting a free quote from an experienced professional. Qualified professionals know how to clean any type of roof and can safely remove dirt, algae and mold, improving the appearance of your roof and extending its life. For a list of professional contractors who clean moldy roofs in your area, just follow the link.