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  • Writer's pictureRainy Day Exteriors

Why Does Moss Grow on Roofs?

Moss growth is a common issue on roofs in Gig Harbor, Port Orchard, and Tacoma. Moss thrives in areas with high humidity levels and low sunlight, and roofs are particularly susceptible to moss growth because they provide the perfect environment for it to thrive.

Let’s talk a little more about how moss grows on roofs and how to prevent it from becoming an issue.

Organic Matter

One of the main reasons why moss grows on roofs is due to the accumulation of organic matter. As debris like leaves, twigs, and other organic matter falls on your roof, it can create a layer of soil-like material that is perfect for moss to grow on. This is especially true if the roof has a shallow slope, as water will not be able to run off as easily, and the debris will remain on the roof for longer periods.


Another factor that contributes to moss growth on roofs is the type of roofing material used. Some roofing materials, such as wood shakes or asphalt shingles, are more porous than others. This means that they are more likely to retain moisture, which creates a perfect environment for moss to grow. Additionally, roofs with a rougher texture, such as wood or slate, provide a surface for the moss to attach to and grow on.

How to Manage it

Moss growth on roofs is not just an aesthetic issue. It can also cause damage to the roof itself. Moss can trap moisture on the roof, which can lead to water damage and even leaks. Additionally, moss can create a barrier between the roof and the sun, which can cause the roofing material to deteriorate over time.

Fortunately, some steps can be taken to prevent moss growth on roofs. One of the most effective ways to prevent moss growth is to keep the roof clean. This involves removing any debris that may accumulate on the roof, as well as regularly cleaning the roof. Learn how to take care of moss in this blog post How to Treat Moss on Your Roof.

Another way to prevent moss growth on roofs is to install zinc or copper strips. These strips are placed along the top of the roof, and as rainwater runs over them, they release ions that prevent moss from growing. While this method is more expensive than simply cleaning the roof, it is a more permanent solution that can save you money in the long run.

If the moss has taken over, and you need to get a new roof give us a call. We offer free inspections and estimates.

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