Moss and lichen growth on your roof is unsightly. This green, grey or white growth diminishes the appearance of the exterior of your home. They tend to grow on parts of the roof that are exposed to little or no sunlight. Moss and lichen will spread farther on the roof if left untreated, and can even cause the roof to weaken over time. Clean moss and lichen from your roof at first sight to prevent damage from occurring.
Pour 1 gallon of water into a bucket. Add 236ml. of oxygen bleach. Use a long-handled spoon to mix up the ingredients.
Transfer the cleaning solution to an empty garden sprayer. If your garden sprayer is large enough to hold an entire gallon of water, mix the solution up in the garden sprayer instead of the bucket.
Use a garden hose to wet the roof thoroughly. Apply a liberal amount of the cleaning mixture onto the roof while it is wet. Let the cleaning solution remain on the roof for 20 minutes.
Scrub the moss and lichen spots off the roof with a long-handled scrub brush.
Rinse the cleaning solution from the roof with water from the garden hose. Rinse from the top of the roof down. Apply the oxygen bleach solution again, then scrub and rinse, if the roof is not clean after the first attempt. Depending on the severity of the moss and lichen, more than one application may be necessary.
Chlorine bleach can also be used to remove moss and lichen from the roof. Mix 1 cup each of washing powder and chlorine bleach, along with 1/4 cup trisodium phosphate, into a clean garden sprayer. Spray the mixture onto the roof, scrub with a scrub brush and let it sit for 15 minutes before rinsing it off with a garden hose. Wear rubber gloves and protective eyewear when using chlorine bleach and trisodium phosphate. Clean moss and lichen from your roof on a cloudy day. This will keep the cleaning solution from drying onto the roof before you can rinse. To maintain a uniform appearance on the roof, consider cleaning the entire surface rather than just the spots with moss and lichen. Cover surrounding landscaping and plants with plastic sheets if you are cleaning the roof with chlorine bleach. Rinse gutters and downspouts after cleaning the roof to get rid of any cleaning solution. Letting the cleaning solution sit in these places can cause corrosion. Wear rubber-soled shoes with good gripping when working on the roof. If you are using a ladder, have another person hold it while you are climbing.