If you’ve noticed black streaks on your roof, or a green moss-like growth, you probably have some form of roof mold or algae growing there. Roof mold is quite common on roofs in more humid climates, and usually occurs on the north side of the house, where it has a tendency to more cooler and wetter. Roof mold is caused by an airborne species of algae. Although the mold doesn’t usually do any actual harm to the roof, it definitely won’t help your house’s curb appeal.
There are a variety of ways to remove roof mold. You could choose any of the variety of products on the market that are specifically designed to remove it. They work well, and you can find them at any good home improvement center. Alternatively, you could use a combination of chlorine bleach and water, but this mixture can discolor asphalt shingles and damage any plants that experience runoff. For that reason, we recommend using a combination of oxygen bleach (in a powder form) and water. It’s an effective solution to get rid of the mold, and it won’t hurt your plants or discolor your roof.
1. Mix the powdered oxygen bleach and water in a pump sprayer. (Never use a power washer on your roof since the force of the spray could damage or loosen tiles.)
2. Spray your entire roof, keeping the surface wet with the solution for at least 10 minutes.
3. Using a soft scrub brush, gently scrub shingles until they’re clean.
4. Rinse the roof with your garden hose.
For more information about removing mold from your roof, visit http://household-tips.thefuntimesguide.com/2010/07/roof_mold_roof_algae.php
Slate roof | Flickr – Photo Sharing! : taken from – http://www.flickr.com/photos/selkovjr/4867374562/Author: selkovjr http://creativecommons.org/licenses/by/2.0/deed.en