Algae on Your Roof – How to Remove and Prevent It

Algae on a roof

Blue-green algae, or Gloeocapsa magma, is the scourge of nice-looking roofs everywhere. You see it driving down almost any street, no matter how nice the homes are – or how new.

You may have noticed it on your own roof and thought, dejectedly, that it meant you needed a new roof. That actually might not be the case. This stuff isn’t mold or mildew, moss or tree sap. It’s actually tiny bacteria. The dark stuff is the coating algae makes to protect itself from the sun.

Here is what makes these little buggers hard to stop: they travel on the wind. That is why it is not your fault. If your neighbor has algae on their roof, you are probably going to get it on your roof too.

Algae likes to live in moist environments and it can eat the dust in the air. Talk about great survival skills! You may notice it more on the north and west sides of your home.

There is no scientific evidence that algae can damage your asphalt shingles, so don’t rush to replace them if they are not old. In fact, there are ways to clean off the algae safely. Because it does affect the appearance of your roof, and no one likes that, and because a darker roof doesn’t perform nearly as well for energy reasons, it is a good idea to have it cleaned.

Dos And Dont’s For Algae Treatment

First, it is critical that you consult with a roofing professional to have your roof inspected and treated properly. There are commercial cleaning solutions for this problem. They remove the stains and keep the algae from growing again for at least a year, maybe more. Additionally, anything else may void your warranty as it won’t be approved by your shingle manufacturer.

The solution to this problem is not:

  1. To go on top of your roof yourself for safety reasons.
  2. To use a brush – as it will most like remove the very granules made to protect against algae growth.
  3. Power wash your roof.

You may also like to read Top 11 Things You Should Never Do to Your Roof

Some shingles are made with metal ions like copper or zinc that can impede algae growth. However, the problem with these is that, over time, the ions are released at a lower and lower volume. In addition, the algae-inhibiting properties go down as the age of the roof goes up.

Slow Release Protection

Most shingles now have some form of slow release protection. These shingles have been on the market for several years now and some claim to warrant against staining for 25 years.

Essentially they are a more highly engineered granule. GAF has recently introduced “Stain Guard Plus.” Atlas has “Scotchguard” technology…all of the manufacturers have some form of and warranty against “algae” streaking.

Renovations Roofing and Remodeling is certified with all major manufacturers, which means we pride ourselves on having the ability to offer you the best of warranties available on the market.


If you have algae stains on your roof, it might be time to consult a trusted roofing contractor to find out about your options. If you elect to replace your roof and live in Southeast Michigan, please give us a call. We would be honored to help!

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