How to Get Rid of Mold on Roof

Mold and mildew buildup on your roof are more than just an eyesore; they can cause structural damage, health issues, and even lower your property value if left untreated. Understanding what causes mold growth and how to remove it effectively can help protect your home and extend the life of your roof. In this guide, we’ll cover the dangers of mold on roofs, the best prevention methods, and the most effective methods for mold and mildew removal on roofs to keep your roof in great condition for years to come.

Is Mold and Mildew Common on Shingle Roofing?

Shingles can be prone to mold and mildew growth, especially in damp and shady micro-climates. This is especially true if shingle roofs are not properly maintained or if there is poor drainage that allows moisture to build up on the roof surface.

Will Mold and Mildew Grow on Metal Roofing like it Does on Shingles?

One question that we get asked is “Will mold and mildew grow on metal roofing like it does on shingles?”

The answer is that because they are non-absorbent and shed water efficiently, metal roofs are more resistant to mold and mildew growth than shingle roofs. Still, mold and mildew can grow on metal roofs under certain conditions like heavy shade or a significant buildup of debris that can provide a surface for mold to grow.

As far as damage, the mold and mildew that may grow on metal roofing doesn’t cause direct damage because metal is not a material that mold can feed on. With that said, mold growth on a metal roof can indicate a moisture problem such as improper installation or condensation buildup, which could ultimately lead to other issues like corrosion or rust. Over time, corrosion and rust can affect a roof’s lifespan, which means that mold and mildew can indirectly cause damage to metal roofs.

Is Mold on Roof Dangerous?

There are three main dangers to mold on roofs: 1. Damage to your structure, 2. Health issues, and 3. Deteriorating property value.

1.     Damage to Your Structure

When a roof has areas covered in mold, it is slowly harming the integrity of your roof. That is because mold sticks to certain organic compounds found in roofs, like wood or asphalt shingles, and slowly eats away at your roof’s durability.

At first, the damage may not be noticeable. Over time, a roof inspection would reveal cracking shingles and brittle tiles, depending on the type of roofing material used on your building. Eventually, the risk of a roof leak grows and once that happens, the entire roof can eventually collapse if it’s not fixed in a timely manner.

2.     Health Risks

Mold releases mold spores into the air, which presents a health risk for everyone, but especially those with asthma or allergies. Breathing in mold spores can cause allergic reactions, including coughing and sneezing, and make it harder to breathe.

3.     Deteriorating Property Value

A roof covered in moss and mold is unsightly and devalues your property because it is seen as a red flag by potential buyers who worry about buying a home and then immediately having to pay thousands of dollars to replace or repair a damaged roof. Not to mention, mold and mildew reduces the curb appeal of the house.

Now that we know the dangers, let’s talk about preventing mold and mildew buildup and how to clean it off your roof before it damages your roof beyond repair.

Preventing Mold and Mildew on Roofs

The best way to protect the integrity of your roof and its accessories from mold and mildew damage is to follow a regular roof maintenance schedule. How often you need to have your roof cleaned will mostly depend on the microclimate your house is in and whether your roof is shaded by trees. In the Pacific Northwest, we do have a fairly mild climate overall but we experience a lot of rain and moisture, some freezing temperatures, and some pretty big wind storms in the fall. If your property has tall trees that block the sunshine and drop debris onto your roof, we recommend a professional roof cleaning about once every 12 months with a general look over twice a year. A professional cleaning provides an opportunity for someone to inspect your roof for signs of damage and clear off debris that could lead to mold and mildew. 

How to Get Rid of Mold on Roof

If your roof already has mold and mildew buildup, it’s best to deal with it as soon as possible before damage is done. Here are the four most common methods for clearing moss and mildew from roofing:

• Bleach and Water Solution. A mix of bleach and water (typically a 50/50 ratio) can kill moss effectively. Apply it with a sprayer, let it sit, and gently rinse it off to prevent roof damage.
• Power Washing. A pressure washer can remove moss quickly, but it can also damage shingles if not done correctly. Low-pressure settings and proper technique are a must to avoid stripping protective granules.
• Trisodium Phosphate (TSP) Mixtures. TSP mixed with water and bleach creates a strong cleaning solution that breaks down moss. It’s effective but should be used cautiously to avoid runoff harming plants and the environment.
• Commercial Cleaning Solutions. Specially formulated roof cleaners are available to kill moss without damaging shingles. There are many eco-friendly options that are designed to prevent regrowth over time.

 Hire a Professional Roofing Company for Safe and Effective Moss Removal

While some homeowners prefer to try and remove moss and mildew buildup themselves, hiring a professional roofing contractor ensures moss is removed safely without damaging your roof. Experts have the right tools, experience, and safety equipment to handle the job efficiently, which reduces the risk of falls or unintentional roof damage.

At Skyline Roofing, our roofing experts use proven cleaning techniques to gently remove moss, dirt, and mold that can damage exterior surfaces. We specialize in cleaning all types of roofs and siding. Maintaining a clean roof can extend its useful life and prevent leaks that could damage the interior of your home.

Trust Skyline Roofing & Construction for Your Roof Maintenance & Installation Needs

At Skyline Roofing & Construction our roofing professionals always strive to add value to your home or business for the long term – that includes installing quality roofing and maintaining your roofing investment. Contact us today to schedule your free consultation for a new roof, roof repair, roof maintenance, or roof cleaning services. Skyline Roofing is located in Bellingham, WA and we presently serve Whatcom, Skagit, and Island Counties.

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