Black or green shingle stains from mold, mildew, or algae can be unsightly. If left too long, they can also eat away at the asphalt granules and begin to compromise your roof’s integrity. It’s important to clean away the mold/mildew/algae on your roof; here, our roofing experts tell you how to remove roof shingle stains with a cleaner:

Preparation

1. First, it’s important to choose the right a roof cleaning day.
   1. Set aside some time on a day that’s cool and overcast with little to no wind.
2. Next, it’s also important that your gutters and downspouts are clean.
   1. Position your ladder against your home and check your gutters. If they have debris in them, clean them out thoroughly so your roof shingle cleaner can wash away easily.
3. After that, make sure the shingles you’re going to clean are in good shape. If needed, make any necessary repairs.
4. Move any furniture or decorations that may be subjected to run-off.
5. Next, use tarps to cover and protect any vegetation that’s close to your home.

Cleaning the Shingles

1. First, choose a non-corrosive roof cleaner from your local home improvement store.
2. Next, position your ladder against your home and make sure it’s secure.
3. Use your garden hose to soak the affected area.
4. After that, mix one part cleaner with six parts water in a pump sprayer.
5. Climb up on the ladder and spray the roof shingle cleaner onto the affected area. Use enough cleaner so that it begins to run off.
   1. (If you’re going to go up onto your roof, make sure you wear slip-resistant shoes and attach a safety harness to yourself in case you fall.)
6. Let the cleaner sit for about 20 minutes.
7. Next, use your garden hose to rinse the area.
   1. If the mold/mildew/algae is stubborn, use a strong hose nozzle setting to dislodge it.

Preventing Regrowth

1. To prevent regrowth of your mold/mildew/algae, install zinc or copper strips along the edge of your roof.
   1. (Every time it rains, tiny metal particles will slide down your roof and will act as a shield to regrowth.)
2. You can also spray your roof with a stain-blocking solution.
   1. If you’re going to do this, make sure you apply it quickly after you clean your roof.