Cleaning and Preventing Mold on Roof Shingles

Published by: Elizabeth Gormley
Published on: 2010-01-10 15:26:13

Having mold or mildew growing on the roof of your home is unsightly, but the black, brown, or green discolorations should be gotten rid of for reasons more than cosmetic.  The powdery specks and streaks can actually eat roofing materials, which eventually may lead you to have to install a partial or entire new roof.  The long process and financial strain will make you wish that you had eradicated the problem when it began.  Getting rid of mold on the roof is relatively simple for the do-it-yourself homeowner—provided you’re not afraid of heights.  So climb the ladder and follow these steps to a mold and mildew-free roof.
    First, make sure that what you see isn’t just dirt.  The best way to determine this is to mix water and a little chlorine bleach and dab it carefully onto the area.  If it’s mold the stain will go away.  Dirt will stay.  Also, before you begin, spray the surrounding plants around your house with water.  It will fortify them from damage caused by the treatments.
    There are two chemical solutions that will kill mold on your roof.   The first one calls for one part bleach to three parts water.  Use a hand-pump sprayer to apply it to all discoloration.  You may want to add some tri-sodium phosphate.  This will clean the shingles as well as kill the mold.  After you spray, let it sit for fifteen minutes.  Rinse with a hose.  If any area still feels slimy, a second application is necessary, but only after the shingles are dry. Be thorough in rinsing the bleach because, like mold, its composition will damage your shingles if left to sit for long.
    The other treatment to rid your roof of mold is mixing copper sulfate and water.  When this is applied to the affected area, the mold should turn brown, or lighter than it had been.  Use a push broom to sweep the mold off the roof.  After, rinse the roof with a hose.
    Mold grows in moisture, so the most affected areas of your roof are likely the ones that get the least amount of sunlight.  It may be necessary to trim overhanging branches to let in the light, air, and stop incessant spore growth.  Foliage shouldn’t be touching the roof.  Keep the gutters clean.  Zinc strips can be purchased at the hardware store.  You can install the strips beneath the shingles at the edge of the roof, where gutters and drainpipes collect rainwater.  The zinc inhibits the chemicals in the moisture that promote spore growth.  If you are installing a new roof, consider asphalt shingles that have a copper additive in their surface granules.  Copper discourages the multiplication of spores.
    As always, when you’re working on a roof, be careful.  Mold is slimy and slippery.  Use caution with water and chemicals.


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