K-Guard Kansas City Blog

What You Need to Know About Roof Algae

roof algae

A home could be stunning on the outside and elegant on the inside but if it has algae on the roof then it can be an eyesore, especially to potential homebuyers. Roof algae is a common roof problem most homeowners face if they live in humid climates like The Heartland.

If you’re unsure whether or not your roof has algae, take a look at it from the outside. If you notice black streaks, spots, or moss growing, you most likely have an algae buildup. As previously mentioned, roof algae is a common roof problem here in The Heartland, especially in the Kansas City region.  

Our team at K-Guard is here to fill you in on what roof algae is, how it can affect your gutter system, and how to prevent and treat it. Keep reading to learn what you need to know about roof algae so you can keep your home looking its best.


What is roof algae?

Now that you know how to identify algae on a roof, you may be wondering what those unsightly black streaks and spots are. Believe it or not, roof algae are aquatic plants that grow and thrive in humid conditions. You’re probably wondering how an aquatic plant can grow on your roof when it’s not submerged in water, and that’s a great question.

Let’s take a quick science lesson to learn about the algae that grow on a roof. Algae stains on a roof are blue-green algae called gloeocapsa magma (say that fast 5 times). These aquatic plants are bacteria that spread rapidly in humid conditions when they’re able to feed on the moisture on roofs. When they spread rapidly they can take over a roof, be pulled down by gravity, and create those downward stains on your roof.  

Unfortunately, algae don’t just stick to roofs. Believe it or not, algae can grow and thrive in a gutter system. When a gutter system has a blockage, whether it be from a buildup of debris like leaves and twigs, a nest left by pests, or algae, it’s unable to properly collect and drain water away from your home. A gutter system that doesn’t function properly can lead to overflowing gutters, flooding, foundation damage, landscape damage, etc.


What are the dangers of roof algae?

The blue-green gloeocapsa magma algae are unsightly and leave dark streaks that are visible, possibly deterring homebuyers. In addition to those unattractive dark streaks, roof algae can shorten the life of a roof. How? Because the algae need moisture to survive, they’ll spread in excess across a shaded roof. When they spread they’ll only retain more moisture and will settle into your shingles, causing them to deteriorate and rot over time.


How can I treat and prevent roof algae?

Roof algae sounds awful, right? While you can’t prevent moisture and high humidity levels from spreading algae, there are a couple of measures you can take to help prevent the spread of algae on your roof. 

Since algae need shade to thrive, you can start by pruning and trimming trees that closely surround your roof. Keeping trees trimmed will expose more of your roof to the sun which helps dry your roof faster, resulting in less of a chance for algae to thrive. Trimming trees near your roof will also help reduce the number of spores that can settle on your roof.  

You’ll also want to make sure that your gutters are kept clean year-round to eliminate the spread of algae in your gutter system. Since algae need moisture, shade, and debris to thrive, untidy gutters are a hotspot for algae to grow. Half-round gutters have moisture and debris, so a single spore can spread from an untidy gutter system up to a roof in the right conditions.

If you do notice algae streaks or spots on your roof then contact a roofing specialist. They’ll be able to help you while keeping your roof safe. Cleaning agents from home improvement stores can cause more damage so it’s best to contact a professional.

Roof algae is a nuisance to all homeowners and chances are you’ve had some on your roof or have noticed some unsightly streaks on neighbors’ roofs. Although it’s a common issue here in The Heartland, keeping trees around your home trimmed and keeping your gutter system clean can help eliminate the spread of roof algae.

The K-Guard Leaf Free Gutter System will eliminate any possibility of algae being spread to your roof as a direct result of an untidy gutter system. Because our complete system is covered by a curved hood, there is no way for debris to enter the system. Your gutters will remain clog-free for the life of the home, helping prevent the spread of roof algae.

We offer free in-home estimates that include a detailed analysis of your current gutter system along with estimated costs for installing your K-Guard Gutter System. K-Guard proudly offers our gutter installation service to homeowners across both Missouri and Kansas including, but not limited to, the following locations:


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