Advise for Asphalt Roofing Control of Black Streaking and Green surface Stuff Growing on 40 Year Architectural Shingles. House is in Connecticut. Regards, D.B.
If you read our ALGAE CONTROL ARTICLE, you’ll learn there are many kinds of mold, fungus and algae which can live on most any structure including the roof of most any house. Once established, these molds can lead to all kinds of discolorations including black streaking. This streaking can sometimes be quite noticeable and cosmetically a nightmare to remove. And though our ALGAE MOLD MOSS KILLER SPRAY will kill the growth and prevent it from spreading, it’s not 100% sure to remove the streaks that have already accumulated.
To treat is very straight forward. The spray concentrate comes in a “ready to spray” container so you don’t need any special equipment to apply it. The container it arrives in simply hooks to your garden hose so you’re able to use the power of your garden spray to reach up and over large areas since most water spigot’s will spray quite far. Use one jug of the Algae Killer per 500 sq/ft of roof to start and be sure to treat all of the roofing so the fungus is knocked down. Since these fungus take a long time to develop – sometimes several years – don’t expect to see any immediate results. We recommend treating monthly for up to 3 months if needed but usually 3-6 weeks following the initial application, you’ll start to see some fading and “disintegration” of the streaks. At that time decide if you think enough of it was killed and whether to apply a second coat or not. In about half of the cases where it’s applied the streaks will disappear and fade away over 3-6 months. But in some cases the roofing will be altered or changed by the algae and these changes can be permanent. That means the streaking will persist even after the algae is killed. So it’s possible that even though you stop the streaking from developing anymore, the old streaks could be there to stay. At this time there are just too many roof types and too many fungus/mold combinations to know for certain whether the treatments will clean the roofing back to it’s original look with all the streaks disappearing or whether something visible will linger. And once any roofing gets a fungus, it’s inclined to develop the problem again in the future so be sure to treat once a year to keep it from returning.
Here are direct links to the information and products listed above:
Algae Control on House Roofing: http://www.bugspray.com/catalog/products/page1621.html#B
Algae Killer RTS: http://www.bugspray.com/catalog/products/page1624.html