The black roof discoloration on your roof isn’t dirt at all. It is what is commonly called a Fungus.
This fungus arrives and collects on roofs here in Tampa Florida, and other exterior surfaces, from airborne spores. Once attached to a shingle or tile roof, the fungus begins to feed on the dead organic matter in and on asphalt and tile roofs. And it feeds on the limestone filler used in the manufacturing process of your roof shingles.
The ceramic roof granules are loosened and begin to fall off as the fungus begins to expand and contract, to break down the asphalt. The ceramic granules protect the roofing material from UV degradation, and once the ceramic roof granules are removed, the roof will begin to deteriorate prematurely. Apple Roof Cleaning Tampa safely removes this deteriorating fungus, and makes an old roof look “new” again.