Removing Algae / Fungus from Stained Roof
Ever notice discolored shingles on some roofs? I’ve seen a couple homes in my area with the dark streaks. This post will focus on what causes the dark streaks, how to best remove it, and what you can do to keep if from coming back.
What Causes Discolored Shingles?
The short answer: fungus. The longer answer: It’s actually a build-up of dead fungus cells. The fungus is an algae (Gloeocapsa magma) that thrives in warm climates with high humidity. Morning dew and rain create a moist environment for the fungus. And limestone from shingles provide the nutrients. There is some debate weather the fungus actually damages the roof. Some say it just looks bad, while others claim the fungus will accelerate the deterioration of your roof.
How to Remove fungus from a Roof
Obviously you can replace your roof. If your roof is old, and the shingles are failing, this may be a great option. Knock out two problems for the price of one. Make sure you purchase shingles with small granules of copper. The copper will prevent the algae from returning.
But what about fulling functional roofs? The best way to clean algae from a roof is a 50/50 solution of water and oxygen bleach. First, wet nearby plants with clean water to protect them. Soak the roof with the bleach solution and then sweep with a stiff brush. Always work down the slope of your roof to prevent damaging the shingles. When you’re done, rinse the entire area with clean water. Don’t use a pressure washer. The high pressure will tear up the shingles.
How to Prevent Algae from Returning
To keep your roof Algae free, install strips of zinc or copper underneath the shingles near the apex of your roof. Make sure that some of the metal is exposed. Tiny amounts will seep out with rain, inhibiting regrowth. These strips will keep moss away too.
What do you think? Know anyone that needs to fight roof algae?
Comments & Conversation on this Article...
2 Responses to Removing Algae / Fungus from Stained Roof:
Leave a comment and join the conversation!
If you want a picture to show with your comment, go get a gravatar!
September 26th, 2008 6:52 pm
Today most modern shingles are manufactured with a small amount of copper granules that help prevent algae growth on the shingles. Copper is actually much more effective in preventing algae growth. I’ve seen quite a few roofs that use a combination of these approaches. You can buy shingles with the copper granules and install a copper or zinc strip under the top row of shingles, this is a belt and suspenders approach.
Great post Ethan, I doubt most people ever knew why the roof was stained, and I’ve heard lots of folks comment that the staining comes from leaves on the roof.
November 20th, 2008 6:53 pm
This is a great article. I’m definitely one of those who didn’t know why the roof gets stained. And Todd, thanks for the info about copper in the shingles. Again, I had no idea, and that’s great info to have before getting a new roof.
A couple years ago, I had dark spots at the base of my roof, and it turned out it was from water damage as a result of clogged gutters. I went ahead and had some gutter covers installed (www.gutterhelmet.com) and haven’t had any trouble since. Does anyone else have experience with gutter covers?