Will bleach ruin roof shingles?

Bleach can ruin roof shingles if used improperly, especially chlorine bleach, which is why shingle manufacturers generally advise against it. There are two types of bleach, chlorine bleach, sodium hypochlorite, and oxygen bleach, sodium percarbonate, with very different effects. Chlorine bleach is harsh and can damage asphalt shingles by stripping protective granules, drying out asphalt oils, and corroding metal flashing, gutters, and fasteners. It can also void manufacturer warranties, as GAF, Owens Corning, and others specifically warn against harsh chemicals. Chlorine bleach runoff can kill landscaping, grass, and plants and is harmful to the environment. Oxygen bleach, on the other hand, is considered shingle-safe when properly diluted and is recommended by many manufacturers for cleaning algae stains. It works through oxidation without the harsh corrosive effects of chlorine bleach. If you must use chlorine bleach, it should be highly diluted, about one part bleach to ten parts water, applied on a cool overcast day, allowed to dwell only 15 minutes, and rinsed thoroughly with low-pressure water, while protecting plants by soaking them before and after. However, for best results and safety, use oxygen bleach or commercial products labeled safe for asphalt shingles like Spray and Forget or Roof Shampoo, which kill algae and moss without damaging shingles or voiding warranties.