What Methods Are There To Removing Or Preventing Moss Your Roof

Here in the Pacific Northwest moss on the northern shady side of the asphalt roof has grown to be a popular problem.


In this blog I want to talk about all the various methods there are out there for removing moss from your roof. We’ll talk briefly about the benefits and risks of each method.


1.) Brushing moss off the roof.

This is probably the most common “do it yourself” method out there. Home owners take a stiff broom or wire brush, climb up on their roof and brush down the moss by hand. Apart from being one of the more labor intensive ways of doing it there are some other negatives as well. Brushing the moss off is similar to mowing your lawn. It will remove the moss for a temporary while but it’s difficult to penetrate down to the roots so the moss is more likely to come back within a few months. It’s also not the safest method as it involves getting up on the roof and brushing every square inch. But there’s an even bigger caution with this method and that’s when it comes to your roofs health and life. Depending on what you use, brushing the moss from your roof can actually remove a lot of the shingle grit or life of your roof. In fact if you use a wire brush it can actually void your roof warranty all together and scrape away years of life. Here are some photos of roofs that have had the moss scraped off, as you can see from the photos, the tar is starting to show on the edges from frequent brushing and much of this roofs life is gone.


2.) Zinc Strips: This is also a very common method for the prevention of moss on your roof. Zinc strips are usually applied at the peaks of the roof,and when rain water combines with the minerals in the zinc it is washed down the roof and kills the moss. It can actually be an effective method in preventing moss but what most homeowners usually fail to do is put enough of it on the roof. Zinc strips will only protect the roof about 3 feet down from where each one is installed. So in order to protect the entire roof, they need to be installed every few feet across the entire roof. Although effective, not everyone loves the “tin foil” look on their new roof.


3.) Pressure washing: Using a pressure washer to blast off the moss, lichen, and algae is another method that some service companies use. In most cases, using a pressure washer on an asphalt roof can actually really damage the roof, removing much of the shingle grit as well as void the roof warranty. Most roofing manufacturers have written this in their roof warranties.


4.) Softwashing: This is the only recommended method by the ARMA (asphalt roof manufacturers association). The roof is treated with a properly proportioned mix of sodium hypochlorite and a surfactant. Usually the mix is pumped from a tank with a 12V battery and applied to the roof at a very low pressure of 30-100psi. It’s applied more like a pesticide spray then a wash. The moss, lichen, and algae soaks up the solution and the solution will kill the moss down to the root. The process, when done right, is completely eco-friendly as the sodium hypochlorite will bio-degrade to salt. The downfall of this method is it does take some time for the moss and lichen to come down from the roof. It’s a long term solution to a long term problem. The moss and lichen can take up to 6 months to come down with the weather. Because this is the recommended method by the roof manufacturers, it is also the method that we use to clean your roof.


5.) Bleach it! If you do some research online about how to treat moss you may find some suggestions that recommend using a laundry bleach to kill it. This is actually true! In fact, the scientific name for bleach is sodium hypochlorite and this is exactly what we use to treat roofs, along with a surfactant to help it stick and dwell on the roof pitch. The tough part with doing it yourself is that the bleach needs to be at the correct percentage in order to get the desired results. Too strong and you can cause damage, not strong enough and it won’t be effective. Depending on how it is applied to the roof, care must be taken as well to protect plants. We don’t recommend this method for homeowners without the proper education. If you are looking for a way to treat a small area by yourself, we recommend a household product called spray and forget . It’s a bleach free, eco-friendly solution to treat moss on your roof. You can read more about it here at sprayandforget.com


I hope this helps give some education on the common ways people treat moss. Especially in what not to do. If you have any questions or want a free consultation and estimate on your roof, feel free to give us a call or send us a message. We are here to help!


Contributed by: Live Next Level Window Cleaning – Foremost Experts in window and gutter cleaning and home maintenance.

Brandon Gawdun
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