Removing Unsightly Black Algae From Your Asphalt Shingles

17 October 2016
 Categories: , Blog


If there are streaks of black on your rooftop's asphalt shingles, you most likely want to find a way to remove them to improve the appearance of your home. Black roof algae usually settles in on the north side of a home, as this is the portion of your roof that receives the least amount of sun. Since sun isn't abundant in this area, moisture tends to stick around longer, making the area prone to dark spots. This algae will continue to grow if steps are not taken to remove it. Here are some tips you can use to remove black markings so you can regain the original appearance of your shingles.

Prepare To Tackle The Problem

Before you get on your rooftop to start working at removing black algae, it is best to prepare the foliage down below. Since you will be using a chemical agent to kill spores, it is necessary to protect your landscaping from unnecessary harm. Wet the grass and plants below your rooftop with a garden hose so that they are completely saturated. This will help keep chemicals from adhering to blades of grass and leaves of plants. When you are done with your cleaning procedure, it will be necessary to rinse all foliage once again to wash away any remnants that stick to them from the process.

Use The Right Solution To Kill Algae Spores

Use a mixture made from equal parts bleach and water to kill the black algae on your rooftop. This can be placed in a pump sprayer. Spray the moldy areas of the rooftop so that they are completely wet with the solution. Use a soft-bristled brush to work the solution into the blackened parts of the shingles. Rubbing them in a circular motion will help loosen the black portions effectively. Allow the solution to sit on the shingles for several minutes. Wash the solution from the shingles using a garden hose. It is best to avoid using a pressure washer, as it can cause lifting of shingles from the impact of the water pressure.

Keep Black Algae From Returning

It may be necessary to repeat the cleaning process a few times to eliminate the black algae in its entirety. To help keep the problem from resurfacing, trim back any tree limbs that shade the rooftop. Consider adding zinc strips along the peak of your rooftop. These are placed under the top row of shingles in a way where a small amount of the strips are exposed. When moisture is present, it passes over the zinc strips, washing tiny metal pieces down over the remainder of the roof. These will kill any algae in their path. 

For more information on how to maintain your roof, contact a company like Ratliff Enterprises.