A Summer Family Retreat

« Back to Home

Frequently Asked Questions About Algae On A Roof

Posted on

If you notice black stains or streaks on the shingles of your roof, you are most likely dealing with gloecapsa magma, or blue-green algae. This algae commonly forms on asphalt and wood shingles when it is warm and humid out. If you notice it forming on your roof, you may have many questions about it. Here are some frequently asked questions about algae on a roof. 

Is Algae Harmful to the Roof?

Algae does not damage or destroy the structural integrity of a shingle. That means that the shingle will not break, crack or fail to work because of the algae growing on top of it. 

What the algae does do is destroy the aesthetic look of the roofing material. And because algae spreads quickly, it can spread across your large portions of your roof if you don't remove it. If it is not removed, it can also cause permanent stains.  Stained shingles can lower the value of your home, decrease your curb appeal and make it more challenging to sell your home if you put it up for sale.

Do You Need to Hire a Roofer to Remove Algae?

Removing algae from a roof is something that you can do yourself, if you so desire. However, before you climb on your roof and begin the process, it is important that you understand the risks involved. When wet, algae is extremely slippery. This makes this task dangerous, especially for those who may have balance issues. If you do not feel comfortable working on the roof or around slippery algae, you can hire a roofing repair company to clean and remove the algae for you. 

How is Algae Removed From a Roof?

If you have decided that you feel comfortable removing algae from your roof yourself, you may be wondering how you can go about doing that. Follow these directions to remove algae from your roof:

  1. Mix a half cup of oxygen bleach with one gallon of water. Place the mixture in a garden sprayer. 
  2. Unwind your hose. Climb on your roof, bringing the hose and your filled garden sprayer with you. Once on the roof, have someone turn on the hose and spray the area of the roof affected by the algae. Do not spray the roof from the ground. It will make it slippery and unsafe to climb on. 
  3. Use your garden sprayer to coat the shingles in a thin layer of the cleaning mixture. Allow it to sit for 20 minutes. 
  4. Spray more of the cleaning mixture on the shingles. This time, use a deck brush to lightly brush away the loosened algae. Do not scrub hard or you could damage your shingles or cause them to fall off. 
  5. Use your hose to rinse the soap residue away. 
  6. If algae spots remain, combine one cup water with one cup household bleach. Put the mixture in a clean garden sprayer and spray it on the affected areas. Allow it to sit for 15 minutes. 
  7. Use your hose to rinse away the residue. Continue coating with the bleach mixture until these tough spots and streaks have lifted.

Is There a Way to Prevent Algae From Forming?

There is no way to prevent all algae from forming. However, there is a way to minimize the amount that grows. 

Adding zinc or copper strips on your roof peaks can help prevent algae from forming. When it rains or the strips get wet, the particles in the metal drip down the slope of your roof. The metal particles change the composition of your shingles, making it difficult for algae to grow and thrive. 

These strips must be properly adhered to ensure that they perform their job without impacting the flow of water. This is a job that you should leave to professional roof contractors, like those at United Roofing. If you improperly adhere these metal strips, you can damage your shingles. And if your shingles are under warranty, you may void the warranty by adding these metal strips yourself. 

While algae may not destroy your shingles, it can make them look old, worn and dirty. Removing and preventing the algae from forming can help your shingles look great for years to come.