A streaky black roof is not exactly a pleasant sight when you pull into the driveway, but there may be more going on with your roof that meets the eye. Of course, with advancements in the roofing industry over the last few decades, you would think that absolutely nothing could damage your roof. But just like anything else, properly caring for your roof can prolong the life and functionality.

What should be cleaned from a roof?

First, we need to explain what’s what: The black streaks on your roof are colonies of blue-green algae, and the thick, green patches on your roof are moss. These conditions occur on a roof when spores of moss and algae are carried by wind or animals, spreading to different roofs. This is also why an entire neighborhood has moss or algae colonies on their roofs. The spores travel easily and thrive in shady areas where moisture is prone to sit. Moisture is basically kryptonite to moss and algae.

How do algae and moss hurt your home?

To put it simply, moss and algae are in two different categories. Moss impacts your asphalt shingles by curling them and forcing them to eventually blow off, potentially leading to a leak in your home. On-the-other-hand, there is a misconception about algae’s impact on the home. Algae doesn’t hurt the functionality of your roof, but it does hurt the homes curb-appeal and may have a slight impact on the value of the home.

DON’T use a pressure washer, which can loosen shingles and seriously damage your roof.

DO use a sprayer attached to a 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 with asphalt shingles. After spraying the roof, allow it to sit on the surface for 15 to 20 minutes before rinsing thoroughly with clean water.

DON’T ignore your landscape or surrounding areas that can be harmed by the bleach solution.

DO wet plants and shrubbery thoroughly with plain water before covering them with plastic. Rinse them again after using the bleach solution on your roof.

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 or if your house is more than one story, you should hire a professional. If you do get up on your roof, wear well-fitting shoes with slip-resistant rubber soles and be sure to wear 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. You can do this with a leaf blower. Also, keep your gutters clean to ensure the roof remains as dry as possible.

Now that you know the best ways to clean a roof, be sure to follow these guidelines carefully. Our roof-cleaning tips only apply for asphalt shingles and the results may take time, especially if you have a lot of moss or algae. The solution may not immediately remove the growth from your roof and you will have to apply the solution again.

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.

Unfortunately, some roofs are beyond cleaning or cleaning the roof may reveal more serious issues. If you are in that situation where cleaning has no impact, give the roofing experts at George J. Keller & Sons a call. We will take a look at your roof for free and discuss the best options for you and your home.

Know you want to replace instead of constantly cleaning/repairing your roof?

We are a GAF MasterElite roofer who specializes in all things roofing.

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