Over time, moss can accumulate between and underneath your roof shingles. Though the image of a mossy-roofed cottage may seem quaint and cozy in paintings, the extensive and costly damages moss can cause your roof are far from picturesque. Over time, moss can deteriorate your roof to the point that your home’s interior and possessions are at risk of moisture intrusion and water leaks. Removing moss from your roof not only helps keep your roof looking like new, but also helps maintain it for years to come.

What is moss?
Moss are small, flowerless plants that typically grow in dense green clumps. It requires a moist environment to grow because moss does not have roots. Moss tends to grow best in a cool, shady climate.

Why is moss bad for roofs? 
There are a few reasons why moss is bad for roofs. As moss thickens and grows, it can raise shingles up. Raised shingles allows water to get under the shingles, causing potential rot and leaks. Raised shingles also increase the chance of shingles being torn off during heavy winds. Moss buildup can also cause more debris to be trapped on a roof, encouraging water buildup and leaks. Moss growth can also damage the asphalt shingles themselves, causing shingles to break down faster.

How do you remove moss?
You or a residential roofing company can remove moss by 1) removing shade and moisture from the environment or 2) turning the environment extremely acidic or basic (below pH 4 or above 7 pH levels). Because moss grows well in shady areas, eliminating shade by removing or trimming trees, branches, bushes, and other plant life to allow for extra sunlight exposure can help get rid of moss. This method is also highly effective in preventing moss, however, can be ineffective in areas where weather is often overcast and cloudy. For those that do not want to remove trees from their yard or live in cool, moist areas, using acidic or chemically basic roofing cleaning products may be a better option. If you choose to DIY rather than employ a residential roofing company, be sure to wear protective clothing, rubber gloves, and eye protection when working with chemicals.

Kill moss by applying chemically acidic cleaners (pH level <4).
Several household products are acidic and highly effective at killing moss. You can either apply them directly to the moss or mix the product with water before application. Using these products with a mixture of water or directly to the moss can kill the plant. Caution should be used when using acids to remove moss. If the acidic mixture is too strong or allowed to stay on the roof for too long, it can erode the roof surface.

Acidic products:
1. White Distilled Vinegar (Apple Cider Vinegar As Well)
2. Orange Juice
3. Lemon Juice
4. Tomato Juice

Use chemically basic products to kill moss. 
Since moss grows in a pH environment of 5-6, making your roof more chemically basic with certain products can effectively kill the moss. You can either apply chemicals directly to moss or mix with water. Below is a list of some common household items that are bases:

1. Baking Soda
2. Baking Powder
3. Salt
4. Ammonia
5. Soap
6. Bleach (Do not mix bleach and ammonia)

Keep in mind that though bleach mix works well, runoff can damage plants. To avoid this, some residential companies choose to skip rinsing the roof after application or rinse plants with 100% water after rinsing roof.

Avoid power or pressure washing. 
Using a power or pressure washer to remove moss, though effective, is highly damaging and will significantly reduce the life of your roof. The high-powered jet of water removes shingle granules that help to protect asphalt shingles, eroding the asphalt shingles. If you do choose to use water to remove moss, do not spray the water at an upward angle. This can cause water to get under the shingles and leak into the house or cause rot.

How do I prevent moss growth on my roof? 
The following methods can help to prevent moss growth on your roof.

1. Remove shade from your roof by removing or trimming trees, shrubs, and plant life.
2. Install zinc or copper strips along the ridges of your roof.
3. String copper wire across the roof using nails or screws ONLY on the side of the roof
4. Clean roof of debris on a regular basis.

So, if you’re noticing moss starting to creep up on your roof, make sure you or a residential roofing company addresses the growth before damages occur. A residential roofing company in Vancouver, WA can not only remove moss from your roof, but also make the necessary installations to prevent future growth.