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How to Properly Clean a Roof

As the summer approaches and the snow has melted, you may notice moss, dirt and other blemishes on different areas of your roof. Shaded areas with little sun exposure tend to be susceptible to these moisture induced blemishes. A dirty roof can taint the entire look of your home and a new roof replacement can be expensive. Cleaning your roof is a good alternative to total replacement and can help to preserve the appearance of your home. 

First, pick a calm and cloudy day to clean your roof. You will want to avoid wind or moisture to ensure your safety, as well as your neighbors.  Cleaning your roof on a sunny day may cause your cleaning solution to evaporate, rendering it ineffective – so avoid sunny days as well. Be sure to clean gutters and downspouts so they are able to drain freely. Any loose or damaged shingles should be replaced before you begin cleaning. 

Assess the safety risks involved with getting up on your roof. If the slope is too steep or the roof is too high, consider hiring a professional. If you are comfortable getting up on your roof, remember to wear eye protection, skin protection and shoes with rubber soles that help to prevent slipping. Also, consider a full body harness.

Move lawn furniture and prepare your foliage. Make sure to wet your plants and surrounding shrubbery with water and cover them up to protect them from the cleaning solution. When you are done cleaning your roof, uncover your plants and shrubs to rinse them again. This step is very important, as any toxic runoff from your cleaning solution could kill your plants or damage your lawn furniture. 

It is important to note that using a pressure washer is a BAD idea and can cause serious damage to your roof. Instead, if you have asphalt shingles, attach a sprayer to a garden hose for an optimum amount of pressure. Fill your sprayer with a 50/50 mixture of chlorine bleach and water. Next, spray your roof with the bleach and water mixture and let it sit for 15-20 minutes. During this process, try to blast off any buildup if you can. Then, rinse the entire surface with regular water. Remember to be patient during this process. The algae and other blemishes may not wash off initially. It will take some time for it to loosen and wash away in a subsequent rainstorm. 

To prevent algae regrowth, you can spray on a coating of stain blocking solution that will protect your roof for up to three years. You can also install zinc or copper strips along the ridge of your roof that will spread algae-killing ions over your roof as it rains. However, neither of these methods are a permanent solution. Be sure to stay on top of cleaning your roof annually to avoid future build-up.