What’s That Stuff Growing on My Roof?

Most people think it is black or dark green mold, but actually, it is a prehistoric bacterium called Gleocapsa Magma. Gleocapsa Magma is the cyanobacteria responsible for the black and dark green stains often seen on roofs. It is transported to roofs primarily by wind, rain, insects, and animals.

In addition to causing unsightly streaks and stains, these bacteria can also wreck havoc on your roof. The growth of Gleocapsa Magma is most accurately described as colonization. These bacteria grow on and within tiles and shingles, dissolving and extracting the mineral components. Overtime, Gleocapsa Magma begins to break down the contents of your tiles or shingles by feeding off the minerals embedded in them. This negatively impacts the structural integrity of your roof and has also been known to increase air conditioning bills and lead to more frequent roof repair and reconstruction.

Unfortunately, Florida’s climate makes the growth of these bacteria very common. The good news is, there are a few options for protecting your roof from damages caused by Gleocapsa Magma:

  1. In the short run, pressure washing can be the least expensive. For a little over $100, you can pay someone to get on your roof every so often to remove the bacteria. However, these results will typically only last 6-12 months. We wouldn’t suggest letting just anyone on your roof to do the job either. It is always best to hire a licensed and insured roofing contractor to pressure wash your roof. That way you know your roof will be cleaned in a safe and professional way without damaging the roof materials or using harsh chemicals.
  2. Roof-A-Cide® is a non-toxic algaecide that can be easily applied to your roof after cleaning. Although Roof-A-Cide® is a bit more costly than pressure washing, when applied properly by a trained professional installer, it provides guaranteed protection for at least two years. Not having to pressure wash for two years can end up saving you money and can protect your roof from the damaging affects of constant pressure washing.
  3. Although more costly upfront, Nansulate® Crystal’s 10-year warranty and energy saving benefits can end up being the most cost effective option for preventing Gleocapsa Magma. Crystal is a thermal insulation coating that provides energy saving insulation, UV protection, mold and moisture resistance. Customers for over a decade report payback from energy savings in 3-5 years. Click here for more information on the benefits of Nansulate Crystal.


Each of these options can also be purchased as an additional item with any of our Roof Assurance Maintenance Program (RAMP) packages. The purchase of any additional menu option will reduce the cost of the program. Whichever option you choose, you can count on the experts at Gulf Western Roofing to provide you with the most reliable service!