CMW Roofing & Siding

CMW Roofing & Siding


Growth on Roof: Understanding the Risks and Remedies

If you’ve noticed some green or black stuff growing on your roof, you’re in the right spot. This page is all about why it’s essential to deal with moss, lichen, and algae on your roof. These aren’t just ugly; they can actually do some damage over time. So, we’re here to break it down for you—what these growths are, why they’re a problem, and what you can do about them.

Types of Roof Growth

Moss: This is the thick, green stuff that can look a bit like a velvety green carpet on your roof. Moss loves moisture and once it settles in, it can hold onto that moisture right against your roof. Over time, this can lead to damage, especially on asphalt shingles, as the moisture can start to break them down.

Lichen: Lichen is a bit of a weird mix between algae and fungus and tends to have a light, mint-green color. Unlike moss, it doesn’t hold moisture in the same way but can be acidic. This means it can start to eat away at your shingles, which is not good news. Lichen can stick to your roofing materials pretty tightly, making it a bit of a pain to remove without causing some damage.

Algae: Ever see black or green streaks running down a roof? That’s usually algae. In many cases, it’s more of a cosmetic issue, making your roof look old and dirty. But, if left unchecked, it can lead to more significant problems down the line. Algae growth is especially common in damp environments and can spread across your roof, affecting its overall appearance and potentially its lifespan.

Moss on roof
Different lichens on roof tile
Shingle roof with molds and algae


Shade and Moisture: These elements create a cozy home for moss, algae, and lichen, especially under the shelter of overhanging trees. These areas on your roof don’t dry out as quickly, creating damp environments where moss grows happily, and algae find its moist haven.

Roof Materials: Different roofing materials offer varying levels of hospitality to these growths. Asphalt shingles, in particular, are prone to algae growth, including the common form known as Gloeocapsa magma. The limestone in these shingles is like a buffet for algae, helping it to spread across your roof.

Organic Debris: When leaves and other organic debris accumulate on your roof or in your gutters, they can retain moisture and even nourish moss and algae. This debris can create standing water, further encouraging moss and algae to eventually grow and thrive.


Algae: Look out for black streaks or greenish patches, which indicate algae growth. These dark streaks are not just an eyesore but can signal the presence of roof algae, detracting from your home’s curb appeal.

Moss: The thick, green texture of moss is unmistakable. If you see it lifting your shingles, it’s a clear sign that moss on your roof is absorbing water, posing a risk to the underlying structure. Moss removal becomes essential in preserving your roof’s lifespan.

Lichen: Less obvious but equally problematic, lichen’s mint-green or crusty appearance clings tight to shingles, hinting at potential damage beneath. Its acidic nature can compromise the roofing materials, leading to wood rot if left unattended.

Before and after cleaning of roof tiles with lichen and algae growth

Physical Damages to Look Out For

Moisture Damage and Wood Rot: The moisture trapped by moss, algae, and lichen can lead to wood rot, significantly shortening your roof’s lifespan and impacting its structural integrity.

Lifting Shingles: Moss growth can lift shingles, allowing water to seep underneath. This not only risks leaks but can also create an environment where mold and other plants might begin to grow.

Blocked Gutters: Moss and debris can clog your gutters, causing water to overflow and potentially damage your roof, siding, and even the foundation of your home.


Letting moss, algae, and lichen hang around on your roof isn’t just a cosmetic issue—it’s a potential threat to your home. Here’s why:

Roof Damage: These growths can cause real damage to roofing materials. For example, moss absorbs water, which can then freeze and expand, causing shingles to crack. Over time, this compromises the roof’s ability to keep water out.

Leaks: As moss and lichen lift shingles, water can sneak underneath, leading to leaks inside your home. These leaks can cause additional problems, such as mold growth and structural damage, which can be costly to repair.

Decreased Lifespan of Roofing Materials: Moss, algae, and lichen can all shorten the lifespan of your roof. By holding moisture against the roof, these growths speed up the wear and tear on shingles, leading to the need for a new roof sooner than you might have planned.

Structural Integrity: In severe cases, the constant moisture and the potential for wood rot can compromise the structural integrity of your roof. This not only poses a risk to your home but can also significantly increase repair or replacement costs.

Prevention Tips to Prevent Algae and Moss Growth

Here are some proactive steps you can take to keep your roof free from unwanted growth and specifically prevent algae growth, including the notorious blue-green algae and moss grow:

Trim Overhanging Branches: Reducing shade on your roof by trimming trees can help minimize the damp conditions that moss and algae love. Plus, it reduces the amount of organic debris that falls on your roof, another contributing factor to growth.

Ensure Proper Roof Drainage: Keeping gutters clean and ensuring downspouts are directing water away from your home can prevent standing water on your roof, a breeding ground for moss and algae. This is crucial in our efforts to prevent moss growth and prevent algae growth, particularly the blue-green algae that can be especially unsightly and damaging.

Keeping gutters clean helps prevent algae and moss growth.

Regular Roof Inspections: Having roofing professionals like us at CMW inspect your roof regularly can help catch and address any issues early before they become big problems. They can recommend specific measures for your roof, depending on its condition and the local environment.

Roof Cleaning: Periodically cleaning your roof safely with a low-pressure setting can remove existing growths without damaging your shingles. It’s essential to approach this task with care to ensure the longevity and structural integrity of your roof. However, it’s essential to use the right cleaning solutions and techniques, as some methods can harm your roofing materials. For the best results, consider hiring a professional roof cleaner who has experience dealing with roof moss and algae.

DIY Removal Methods

When tackling moss, algae, and lichen on your roof by yourself, the goal is to be effective without causing damage to your roofing materials. Here are some safe DIY methods:

Gentle Removal: For moss, use a leaf blower or a soft brush to gently remove any loose moss from the surface of your shingles. Avoid using a pressure washer, as the high pressure can damage the shingles.

Cleaning Solution: You can make a cleaning solution with gentle, environmentally friendly ingredients. For algae and lichen, a mixture of water and white vinegar can be effective. Spray it on the affected area, let it sit for about 30 minutes, and then rinse off with low pressure water. For tougher jobs, a mixture of water and bleach (1:1 ratio) can be used, but be careful with plants and grass around your home as bleach can harm them.

Preventative Sprays: After cleaning, applying a solution that contains copper sulfate or zinc sulfate can help prevent future growth. Just remember that runoff containing these chemicals can be harmful to plants and aquatic life.

When to Call a Professional

While many moss, algae, and lichen issues can be addressed with DIY methods, there are times when it’s best to call in a roofing professional like us at CMW Roofing & Siding:

Steep Roofs: If your roof is steep or difficult to access safely, it’s worth getting our professional services. We have the right equipment and training to do the job without risking injury.

Extensive Growth: When the growth covers a large portion of your roof or is particularly thick, we have the tools and experience to remove it effectively and safely.

Underlying Damage: If you suspect that the growth has already caused damage to your roof—like lifting shingles, leaks, or wood rot—it’s crucial to consult us. We can assess the damage, perform necessary roof replacement or repair, and remove the growth without causing further harm.

Preventative Treatments: We can also offer more durable solutions, like installing copper or zinc strips along the ridge of your roof, which can help prevent the growth of moss, algae, and lichen in the long term.

We have the expertise to deal with these issues safely but can also provide advice on maintaining your roof and preventing future growth. If you’re unsure about the condition of your roof or how to tackle the problem, it’s always best to seek our professional advice. This ensures your roof remains in good condition, protecting your home effectively.

"CMW completed my roof, siding, gutters, and windows. Company is very professional and responsive. They did a great job with all services provided. Highly recommend CMW Roofing & Siding!"

Professional Solutions at CMW Roofing & Siding

At CMW Roofing & Siding, we understand the challenges that come with maintaining a clean and healthy roof. That’s why we offer comprehensive services to tackle moss, algae, and lichen growths that can compromise the integrity and appearance of your roof. Our team of experts provides:

Professional Assessment: We start with a thorough inspection of your roof to identify the extent of growth and any underlying damage it may have caused. This ensures we understand the full scope of the issue before recommending the best course of action.

Safe Removal: Our trained professionals use industry-best practices to safely and effectively remove moss, algae, and lichen from your roof, all while ensuring your roofing materials are preserved and protected.

Preventive Treatments: To keep your roof looking its best and prevent future growths, we offer preventive treatments. This includes the installation of copper or zinc strips and the application of protective coatings that inhibit the growth of moss, algae, and lichen.

Maintenance Advice: We don’t just stop at cleaning; we also provide valuable advice on how to maintain your roof and prevent future growths. This includes tips on gutter maintenance, proper drainage, and trimming overhanging branches.

Contact Us

Don’t let roof growths bring down the beauty and functionality of your home. Whether you’re dealing with a small patch of moss or a roof full of algae, CMW Roofing & Siding is here to help. Contact us today for a professional roof inspection and say goodbye to roof growth concerns. Let us restore the beauty and integrity of your roof with our expert services.

Reach out to us now and let CMW Roofing & Siding take care of all your roofing needs. Our team is ready to provide you with top-notch service and ensure your roof remains in perfect condition for years to come.

Kyle Clarkson
Kyle Clarkson
CMW Roofing & Siding does a great job. They are quick, easy to work with and have affordable pricing for new siding projects.
Drew C.
Drew C.
Great service at a great price. I called them to ask when they would start and they let me know that the work was already completed. I had someone go check it out and the gutters looked great.
I have had the pleasure of working with Henry for a few years now. Any time we have ever had any issues with leaks Henry arrives as quickly as possible and offers a wide array of solutions tiered to my price range. He is knowledgeable, kind, and caring with my family and I. He has always worked with us to offer the best long term solutions to our problems and he comes highly recommended from me. It is a rare thing to find a contractor who cares about your home, with CMW I have found just that. Thank you to Henry and his entire team for always being there to find solutions for our home.
Alex Fucci
Alex Fucci
i had water leaking from the roof . after calling 3 companies CMW was the only one that answered the phone. they installed new roof shingles and new siding that was damaged, they did an excellent job, yhank you.
Leslie Feltham
Leslie Feltham
Xavier is great. He is honest and makes you feel comfortable. All the work was done quickly and efficiently! This company is amazing. If you need the services they offer, 100% hire them! Honest, kind, compassionate. I can't say enough good things about them.
Vincent Ziccolella
Vincent Ziccolella
Simple call, Henry had his crew out right away! We had new gutter helmets installed and couldn’t be happier!
Blake Demetro
Blake Demetro
All around amazing experience Communication skills were excellent installation Quick and clean, left my property as clean as it was before they started The CMW team is the best highly recommended
Justin Scheckler
Justin Scheckler
Xavier and his team were phenomenal with helping us and guiding throughout the process of replacing our roof. Very thorough and very patient with all of our questions every step of the way. The roof looks great and we know it will last most of our lifetime. We even had a small hiccup with our flat part of roof that wasn't draining great(no fault to CMW just an old support beam) and Xavier came out promptly and made adjustments to fix everything no questions asked. I think these guys really do pride themselves in their work, and care about making the customer happy. Xavier also didn't pressure us about any sales at any point and told us not to worry about our siding for awhile. Something we were concerned about, and that there's no rush to do that project while we save. That really goes a long way for the customer to know that they'll be available when the time comes, but when we feel ready. We will definitely be using them again when it comes time to do siding. Thank you Xavier and CMW
Gina Kastner
Gina Kastner
I highly recommend CMW roofing. We had a roof and gutters replacement. The owner and his team were professional and knowledgeable. The employees arrived and worked in unison to ensure the job was completed on time. We were extremely pleased with the cleanup and the overall experience and outcome of this project. Thank you Henry and your great team.