Moss vs Algae: Which Is the Real Challenge for Your Roof?

Moss vs Algae: Which Is the Real Challenge for Your Roof?

It is the first line of defense you have to win the battle against costly repairs that come with water damage. So,  it’s very important for your roof to be clean and well-maintained. Moss and algae are two of the most typical problems homeowners encounter with their roofs. They may resemble each other in their manner of growth and damage, but mosses and algae are quite distinct. Knowing these differences is the key to selecting the right solutions for a strong, lasting roof. In this article, we will break down what moss and algae are, how they impact your roof and how to best prevent and clean effectively.

What is Moss on the Roof?

Moss on the Roof is a type of non-vascular plant that forms green clumps or mats on the roof which are soft and thick to touch. It does well in moist, shady areas where water doesn’t quickly evaporate.

Causes of moss growth

• Tree or building shaded roof areas
• Sections of roof, facing north and receive less sunlight
• Damp conditions and high humidity
• Roof surfaces that retain moisture
• Poor ventilation, causing prolonged wetness
• Build up of organic matter such as leaves
• Cool, mossy, conducive environments

Signs of moss on your roof

• Clumps of green, velvet-like patches on the ground!
• Found in moist, shady places such as valleys and gutters
• Chappeled, lifted or raised shingles from moss beneath
• Water tends to remain as a film on the roof
• The dark green growth spreads primarily when it rains
• Detritus such as leaves or twigs can accumulate near moss.

What is Roof Algae

Algae is a simple single-celled organism that can become dark green, black or brown -basically evident in streaks and patches. It does well in damp, shadier locations and feeds on nutrients such as the limestone found in roofing materials.

Causes Algae Growth on Roofs

• High humidity and damp environments
• Inadequate ventilation where moisture is being trapped in the roof
• Areas shaded with low direct light.
• Nutrient organic deposits of leaves and dirt
• Rainwater accumulation and clogged gutters
• Roof coverings that incorporate limestone fillers, specifically asphalt shingles

Key signs of roof algae:

• Roof streaks of black, dark green or brown
• Discolored or blotchy shingles
• Algae acid stains on the gutter
• Green or white patches that show up on the roof
• In the event of a damp roof and moss growth
• Dark streaks in north or shaded roof areas typically

And if you spot them early, you can prevent their unsightly damage before they can ruin the appearance and effectiveness of your roof.

Moss vs Algae: Which Is Worse for Your Roof?

Moss is generally worse for your roof than algae. Moss forms thick, cushiony clumps that can lift and separate shingles, trapping moisture underneath. This is causing water damage, rotting of the wood, and structural problems.   

However, algae tends to look like black flat streaks or stains. While algae primarily affect your roof’s appearance by causing discoloration, they do not cause significant immediate damage.  Algae can speed up shingle degradation, wearing down with the erosion of protective granules over time.

In summary:

• Moss actually physically harms roofing materials and it holds water, so it is the bigger enemy.
• Algae are primarily a cosmetic concern, but they can help in the long-term aging of a roof.
• Both need to be treated for the health of your roof, however, moss is more of a threat to your home’s structural integrity.   

How to Remove Moss and Algae from Your Roof

Cleaning your roof of moss and algae is necessary for its longevity and to keep it looking good. Here are effective methods:

Use a Gentle Cleaning Solution

Combine water with a mild bleach or specialized roof cleaner. Spray the solution onto problem areas and then wait for results: 20-45 minutes to kill moss and algae. Be sure to always exercise caution and shield surrounding plants.

Soft Washing Method

Wash moss and algae away with low-pressure water combined with cleaners that are safe for shingles. Do not pressure wash this tends to make the shingles come loose.

Hand Pick With Soft Brush

Then gently brush the moss away with a soft broom or brush, moving down to keep from lifting shingles for patches, do the trick.

Rinse Thoroughly

After treatment, use a gentle garden hose on low pressure to rinse the roof and remove dead moss and cleaning solution.

Hire Professionals

For significant growth or if you have safety concerns, bring in pros who have the equipment and knowledge to safely and effectively remove them.

Long-Term Prevention

• Prune tree branches to add sunlight
• Attach zinc or copper strips to the roof ridge to stop it from growing
• Clean gutters and maintain proper ventilation
• Conduct routine roof inspections and cleanings

Conclusion

Mildew and algae growing on your roof can result in costly damage if not addressed properly. Moss is a bit more destructive as it lifts and tears at the shingles and traps moisture that causes leaks and rot. Algae, for the most part, disfigures the roof but slowly disintegrates shingles. Inspections, cleaning and preventive maintenance are the key to maintaining a healthy roof. For professional moss and algae removal, roof inspections, and quality roofing solutions, you can rely on Down to Earth Roofing.    

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