Roof Mildew Staining

Mix the soap and water well first then add the bleach.

Roof mildew staining.

The bleach degrades into salt which kills microbial growths and the sodium silicate does the same. You could replace all the roofing with new shingles dark enough to disguise the staining or with shingles laced with copper granules which are lethal to algae. Spray the black stains first then the entire roof so the stains get a second dose. Here is a diagnostic guide to types of stains and staining materials found on roof surfaces black red green brown or other coloured stains on asphalt roof shingles or on other roofing materials need first an accurate diagnosis of the stain cause and then proper steps to remove the stain or to prevent future staining on roof shingles surfaces.

When that happens it is generally caused by mildew algae mold or dirt stains. If your household water pressure isn t enough to generate the proper nozzle pressure at the jets the manufacturer recommends boosting it. But that would only make sense if the shingles were worn out. It is not uncommon for roof shingles to turn black over time.

The less expensive solution is to spray wash the roof with a 50 percent mix of water and bleach to get rid of the algae.