In this article, we will discuss why cleaning moss from a cedar shake roof is important.
Moss growth can create several problems on shake roofs. While a small layer of thin moss isn’t as troublesome, large clumps of moss can degrade shakes, get beneath them, and create opportunities for leaks. Further, many of the methods of removing moss recommended online actually damage the shakes, which could significantly increase your odds of getting a leak. So, how do you safely remove moss from a shake roof? How do you prevent moss from growing back after you have removed it? I’ll answer those questions and tell you other things you need to know about handling the moss on your shake roof.
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Why is Moss Bad for Shakes?
You may feel that a bit of moss gives your roof some charm, just as ivy growing up the side of your house might. While moss may be beautiful, it is a detriment to your roof. Here’s why:
Most plants gather water from their roots, but mosses gather water from their leaves. Therefore, they do not mind that shake, unlike soil, are a dry and relatively nutrient-free environment. They will grow roots directly into the shakes, destroying the shakes and creating the opportunity for leaks.
When it rains, moss will soak up water and retain it, creating consistently wet conditions on your roof. Moss growth will also interfere with the proper drainage of water off the roof as water needs to trickle through or around the moss instead of running straight down to the gutters. The resulting constant exposure to water can degrade shakes.
Over time, moss can also work its way under shakes, lifting them. This uplift creates opportunities for water to penetrate lower layers of the roof and, potentially, your home.
While minor moss infestations may appear not to cause many issues, it is likely to become severe over time. Once you spot moss growth on your roof, you should take steps to resolve it. If you have a severe infestation, you may have no choice but to remove the shakes that have been damaged by it. A professional roof cleaner can help you assess what kind of intervention your roof needs.
What if the Moss Appears Dead?
If the weather has been consistently dry, moss may appear to be dead. However, some species of moss can stay alive when dried out for months. All it will take is one rain for it to recover and continue growing. If your moss has dried out, take the opportunity to have a roof cleaner remove the moss from the roof.
How To Remove Moss from a Roof
If your roof has sprouted a moss infestation, you can remove it before it becomes serious enough to impact the performance of your roof. Moss is tough, and typically you will not be able to pull it by hand. However, you can use a chemical solution to loosen the moss without damaging the shakes. I don’t recommend that you step on the roof for moss removal.
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Step One
Safely set up your ladder near the moss. Use a ladder with a standoff on it to raise you above the roof. With either your homemade cleaner or a store-bought option, spray the moss. I use a citrus-based cleaning solution that I developed myself.
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Step Two
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Step Three
Using your garden hose on low pressure, rinse the moss thoroughly. You should find that most of the moss will come off from the spray of the water. Be sure not to direct a pressurized spray beneath the shakes. Otherwise, you could create a leak. It is not necessary to remove all the solutions. I always leave some of the answers in my process because I use a steam process oil to help rehydrate the shakes.
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Step Four
You may find it hard to remove all loose moss. Don’t concern as a good rain will rinse such down your roof. Now either rinse out your gutters or clean them by hand.
Methods You Should Not Use When Cleaning Moss From a Cedar Shake Roof
Unfortunately, there is a lot of bad advice out there about how to remove moss. While these methods may appear effective at removing moss, they can also damage shakes in the process. I don’t recommend you try to clear your moss by:
Scrubbing
You may be tempted to scrub the moss off the shingles because moss grips shingle pretty strongly. However, scrubbing is likely to damage the shakes.
Pressure Washing
Pressure washers can be powerful and undoubtedly strong enough to break shakes and lift them. Any amount of pressure washing can cause severe problems with the roof, including significant leaks. Never use a pressure washer or a pressurized stream of water on your roof.
Using Harsh Chemicals
High concentrations of bleach and other chemicals may do permanent damage to the shakes, increasing your risk for leaks. However, small amounts of bleach/pool chlorine are very effective at killing bacteria.
How To Prevent Moss on Your New Roof
Remove Sources of Shade
Moss prefers to grow in the shade, so exposing more of your roof to sunlight will help deter it. It would help if you considered trimming trees that shade out the roof or moving garden features, like pergolas or trellises, so that they do not cast shade on the roof.
Algaecide and Fungicide
Where there’s moss, there is also algae and fungi, as they thrive on the same wet and shady conditions. You can lessen algae and fungi infestations by using an algaecide and fungicide within the cleaning solution.
Cleaning and Treatment
Every cedar shake roof should be cleaned and treated every 7 to 10 years. Cedar shakes are organic and need to be maintained.
Get Regular Inspections
Roof cleaners can often prevent moss growth by ensuring that your roof is draining water properly. They should inspect and clean your gutters yearly to avoid the backup water that could attract moss.
What if the Moss Grows Back?
You should not see moss return between cleanings if you have trimmed back surrounding tree cover and avoided shade on the shake roof. If the moss returns and you did the cleaning, you should contact a roof cleaner that has experience with cedar shake roofs. If cleaned and treated correctly, moss should not return.
Do You Need Help Dealing with Moss?
Bruce Sullivan is the owner of Sullivan Roof Cleaning, Inc., with over 50 years of cleaning, maintaining, and restoring cedar shake roofs. Contact Bruce today and get a quote for your roof.
