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Why are Moss Removal & Treatments Good for Your Roof?

Updated: Dec 20, 2023


In the damp climate of the Pacific Northwest, the presence of moss on roofs is unavoidable - you probably can see some on your own roof now! This common plant clings to shingles and can cause damage that might necessitate costly repairs or even a roof replacement.


The moisture in this region is unavoidable but moss also requires shade to grow. The key to curbing its growth can be helped by trimming trees to allow sunlight to reach the roof's surface. Jay Pscheidt, a plant pathologist at Oregon State University Extension Service, emphasizes that cleaning alone won't keep moss at bay; the environment needs to change. You must let the sun in, or the moss will return.


The growth of moss causes as it traps soil and debris, which in turn retain water and keep the roof damp for extended periods. This creates conditions conducive to the growth of moss and fungi. This greatly accelerates the decomposition of wood roofs especially, but it will still damage asphalt and metal roofing as well - don't be fooled!


Therefore, regardless of the roofing material, it's important to keep roofs clean.Despite the fact that many people appreciate the aesthetic appeal of moss, keeping it off the roof is crucial for the roof's durability. It is also very important to remove moss from areas like decks and steps to prevent slip and fall accidents. (If you're a moss enthusiast, consider allowing it to grow in designated garden areas where it can be enjoyed without posing a safety hazard!)


Prior to applying any moss-killing treatment, it's essential to clean the roof. If you're skilled in using a pressure washer, you can use it for cleaning - but please use proper safety precautions! If you're not experienced, it's best to hire a professional, as improper pressure washing can damage your roof, and washing your roof can be a risky endeavor - here at Flow, we value your safety! If you do not have a pressure washer or do not feel comfortable with a pressure washer but want to do some maintenance, you can use a long-handled scrub brush for cleaning the bulk of the debris off.


Once the roof is clean, you can apply one of the following solutions using a pump-style sprayer:

  1. Zinc sulfate (monohydrate): Mix 3 pounds of powder in 9 gallons of water. This mixture can treat 600 to 1,000 square feet of roof using a pump sprayer, depending on the condition of the wood. In areas with heavy moss growth or conditions favorable to moss, use a solution of 1 pound of powder mixed in 3 gallons of water to treat 200 square feet. Avoid this treatment if you have copper gutters, downspouts, or flashing, as zinc sulfate can corrode copper.

  2. Potassium salts of fatty acids: These biodegradable, soap-based products kill moss by penetrating the cell walls and altering the membranes, causing the moss to die. These products are noncorrosive and pose minimal risk to humans and animals.


When using these chemicals, be cautious not to overspray on nearby plants, as it can harm them. Rinse any plants that are accidentally treated, and thoroughly rinse any tools or equipment used for applying these products.


If you're unsure of your capabilities, it's best not to attempt this task.


No matter your experience, roof maintenance best practices are as follows:

  • Wear shoes with good traction for better grip on the roof.

  • Place your ladder on stable ground, ensuring it extends at least 3 feet above the roof line, and secure the top to the roof if possible.

  • Use a bucket and rope to transport tools and other items to the roof instead of carrying them up the ladder.

  • Use safety belts and lines when the roof pitch is steeper than 23 degrees, when you're working within 6 feet of the edge, or when the eaves are over 16 feet from the ground.

  • Pay close attention to the safety instructions on the product labels you use.

  • Make sure someone knows where you are and that you're cleaning the roof.


Moss Removal & Treatments Good for Your Roof!

Moss can seriously impact the health and integrity of your roof:


Enhances Roof Longevity

Moss often causes the roofing materials to deteriorate rapidly. It retains moisture, and over time, this moisture can seep into the roof's structure, leading to rot and damage. Regular moss removal and treatments can add years to your roof's lifespan.



Prevents Structural Damage

The presence of moss on your roof can result in structural damage. As it retains water, it can cause your roofing materials to weaken, potentially leading to leaks and even collapse in extremely neglected cases. Moss removal helps prevents these costly structural issues.


Preserves Curb Appeal

A moss-covered roof is far from appealing. It can make your home look neglected and unsightly. Regular moss treatments ensure that your roof remains aesthetically pleasing and boosts your home's curb appeal.


Increases Energy Efficiency

Moss on your roof can affect your home's energy efficiency. In extreme cases, it acts as an insulator, trapping heat and making your home warmer in summer and cooler in winter. This forces your HVAC system to work harder, resulting in higher energy bills. Moss removal helps maintain your home's energy efficiency.


Avoids Health Hazards

Moss can be a breeding ground for harmful organisms, such as mold and algae. These organisms can release spores into the air, potentially causing respiratory problems and other health issues. Moss treatments eliminate these health hazards.


Complies with Warranty Requirements

Many roofing warranties require proper maintenance, which includes moss removal and treatments. Failing to do so could void your warranty, leaving you responsible for costly repairs.


FAQs about Moss Removal & Treatments


Is moss removal a DIY job?

Moss removal can be a DIY project if the growth is minimal. However, for extensive moss coverage, it's best to hire a professional who can safely and effectively remove it.


How often should I schedule moss treatments?

Moss treatments are typically recommended on an annual or bi-annual basis, depending on your local climate and the severity of moss growth.


Are moss treatments environmentally friendly?

Many moss treatment products are eco-friendly and safe for your roof. However, it's essential to consult with a professional who can recommend the best solution for your specific situation.


Can I prevent moss growth in the first place?

Prevention includes proper roof maintenance, adequate ventilation, and ensuring your roof receives adequate sunlight. These practices can minimize moss growth.


What is the cost of moss removal and treatments?

The cost varies depending on the extent of moss growth and your location. On average, it can range from $100 to $1000 or more. Moss treatments may require multiple treatments. Moss removal is labor intensive which has a higher cost.


**Can moss removal harm my roof?

If done improperly, moss removal can damage your roof. It's best to leave it to professionals who know how to remove moss safely.



Moss removal and treatments are not just cosmetic enhancements for your roof; they are vital for its health and longevity. By preventing structural damage, preserving curb appeal, and increasing energy efficiency, you can protect your investment and enjoy a comfortable and safe living environment. Don't wait until moss becomes a significant problem; invest in regular maintenance to ensure your roof's well-being.

Remember, when it comes to moss removal and treatments, it's always best to consult with a professional to assess your unique needs and ensure the job is done correctly. With their expertise, you can be confident in the longevity and functionality of your roof.

Ensure your roof's health and longevity by taking action today. Say goodbye to moss-related issues and hello to a secure, attractive, and energy-efficient home.




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