A funky green furry stuff and discoloration is on my roof, so I’ve put clean roof mildew on my “to do” list. It all started one day when I stopped and really looked at my house’s roof. It just didn’t look new any more.

Not all ‘killers’ are big, fast, scary looking, or have big teeth. When I checked with a roofer, I found out that the black stains are mildew which happens in a humid climate. Having trees around your house can create a micro-climate that has positive and negative effects. First, the landscaping adds beauty. The trees provide shade, keeping the house cooler, and shelter the house from wind. However, when they are too close over the roof, leaves, flowers, and sticks build up on the roof and gutters, holding moisture, and the shelter can keep it from evaporating. Into this environment comes…mildew. Mildew or mould is a simple plant whose roots, although superfine, break down what they grow on. I wanted my roof to last so the mildew had to go.

First I had the trees trimmed back to allow air circulation. Then I called a roofer to wash down the roof. They said power washing is no longer recommended because it can cause more damage than it prevents. One option for cleaning off the mildew is a TSP/bleach mix, although the high sodium content of bleach causes a chemical reaction that reduces the elasticity of the asphalt. There also are some bleach-free chemical treatments to apply, some after or instead of bleach. A natural alternative to prevent future growth is zinc strips nailed to the roof. They dissolve a little each time it rains, and the zinc prevents mildew growth. Now things look better and will last so my recommendation is: Yes, you should clean roof mildew!

Written by: https://roof.net/

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