If you’re reading this, chances are you’re looking for roof-cleaning tips because your shingles are no longer looking new and attractive. If your roof appears dark and discolored in some areas, you may think that mold has developed on the surfaces of the shingles. However, the black streaks you’re seeing are really colonies of blue-green algae. If you’re noticing thick, green patches on your roof instead, then you’ve got a moss problem, The north, west, and shady areas of your roof are most susceptible to these moisture-loving nuisances.

black streaks on roof

Moss and algae spores are carried by the wind or animals from rooftop to rooftop, which is why entire neighborhoods are often affected. Moss can seriously impact asphalt shingle performance by causing them to curl up and blow off, eventually resulting in leaks. While algae doesn’t actually harm your roof, it can impact its aesthetic appeal. Further, climbing on your roof frequently to clean off growth CAN damage your roof and shorten its lifespan by loosening the granules on your shingles. So, it’s best to know how to clean your roof properly so that you ensure you don’t have to do it too often.

Knowing this, what are the best ways to clean a roof of algae and moss growth? Read on for our best roof-cleaning tips!

Don’t: Use a pressure washer, which can loosen shingles and seriously damage your roof.
Do: Use a sprayer attached to garden hose that’s filled with equal parts chlorine bleach and water. of laundry strength liquid chlorine bleach and water. This is the best way to clean a roof if you have asphalt shingles. After spraying the roof with the mixture, allow it to sit on the surface for 15 to 20 minutes before rinsing thoroughly with clean water.

Don’t: Ignore your landscape and surrounding areas, which can be harmed by the bleach solution
Do: Wet plants and shrubbery thoroughly with plain water before covering them with plastic, then rinse them again after using the bleach solution on your roof.

Don’t: Assume the solution will immediately remove the growth from your roof and apply the solution again.
Do: Have patience. The algae will wash away during subsequent rainstorms, and moss will eventually loosen to the point where it can be removed with a leaf blower.

Don’t: Clean your roof on a sunny day, which will cause the bleach solution to evaporate too quickly, limiting its cleansing effects.
Do: Clean your roof on a cloudy, calm day when the wind isn’t blowing and there’s no threat of precipitation.

Don’t: Clean your roof without taking proper safety precautions.
Do: clean your roof only after determining that you can safely walk its surface. If the slope is too steep to easily traverse or if your house is more than one story, you should hire a pro. If you do get up on your roof, wear well-fitting shoes with slip-resistant rubber soles and be sure to don eye and skin protection.

Don’t: Wait until your roof is covered in algae or moss to take action.
Do: trim back overhanging branches to expose the roof to sunlight, and clear debris such as branches and leaves, from its surfaces with a leaf blower if needed. Keep gutters clean to ensure roofs remain as dry as possible.

Now that you know the best ways to clean a roof, be sure to follow these guidelines carefully. Note that our roof-cleaning tips only apply for asphalt shingles. If you have another type of roof, it’s important to check with your manufacturer to find out how to clean your roof. In fact, it’s wise to consult your manufacturer for roof-cleaning tips regardless of what type of shingles you have in order to avoid inadvertent damage.

Sometimes roofs are beyond cleaning or the cleaning reveals other, more serious, issues. If that’s your situation give the roofing experts at George J. Keller and Sons a call today at 973-927-0963 and we’ll inspect your roof for free and discuss your options.