Is there a safe homemade roof moss cleaner recipe?
Short answer. The safest homemade roof moss and algae cleaner is plain household bleach diluted with water at about one to one, the ratio roofing manufacturers describe for algae. Oxygen bleach mixed exactly as its package directs is a gentler option. Avoid improvising stronger mixes, and never combine bleach with ammonia, vinegar or other cleaners.
Recipe 1: diluted bleach
- Plain, unscented household bleach and water, roughly equal parts, in a garden pump sprayer.
- Good for: algae streaks, mildew, thin moss.
- Apply at low pressure on a cool, cloudy day, then rinse as your shingle maker directs.
Recipe 2: oxygen bleach
- Sodium percarbonate powder dissolved in warm water at the strength printed on the package.
- Good for: stains and mildew where plants are close to the eaves.
- Use it the day you mix it; it loses strength as it sits.
What about vinegar, dish soap or baking soda?
Household vinegar and soap may knock back thin moss but often leave the base alive, so it regrows. Baking soda can work on small patches but leaves residue. None of these beats a product labeled for roof moss.
Mixing rules that keep you safe
- Never mix bleach with ammonia, vinegar, acids or other cleaners. The fumes are toxic.
- Mix outdoors and label the sprayer.
- Wear goggles and gloves; spray drifts back at you when working overhead.
- Do not add more bleach thinking it will work faster; it mainly increases plant and metal damage.
Protecting the roof and yard
Wet and cover plants, flush gutters afterward, and keep runoff away from ponds and storm drains. Remove dead moss by hand or soft brush, downslope only, and never pressure wash shingles. For the bigger picture, see moss and lichen on roofs and black streaks and algae on roofs.