What roof algae removal spray works best?
Short answer. Roof algae sprays fall into three groups: bleach based sprays that work fast, oxygen bleach (sodium percarbonate) cleaners that are gentler on plants, and slow acting spray and leave products that rely on rain over weeks. Whichever you use, apply at low pressure and never pressure wash shingles.
The main spray types
- Bleach based (sodium hypochlorite): the fastest visible results. Diluted household bleach is the method roofing manufacturers describe. Hard on plants and metal if not rinsed.
- Oxygen bleach (sodium percarbonate): mixed from powder with water. Gentler on landscaping, slower, and may need a second application.
- Spray and leave products: often based on quaternary ammonium compounds. Sprayed on a dry roof and left; rain gradually rinses away the dead growth over weeks or months. No rinse step, but patience required.
Choosing one
- Need it clean soon, such as before listing: bleach based soft wash.
- Lots of plants close to the eaves: oxygen bleach or a spray and leave product.
- Light streaking you can wait on: spray and leave.
Read the label to confirm the product is approved for asphalt shingles, and check your shingle warranty for approved cleaning methods.
Applying a spray
- Clear leaves and pine needles first.
- Wet and cover plants below.
- Spray low pressure from the bottom of each streak upward.
- Rinse or leave, according to the label.
After it is clean
Algae returns in Georgia's humidity. Zinc or copper strips near the ridge slow regrowth, and algae resistant shingles are the long term fix. See black streaks and algae on roofs and the Georgia roof maintenance checklist.