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Moss lying on shingles

Along the roof where there is more shade from nearby trees, you may have noticed that the normally dark shingles have a green appearance. That green substance is moss. While moss may look pretty and give a more natural, woodland appearance to your home, it can actually damage the roofing system.

Moss lying on the roof

Moss grows in shady areas of the roof. So it is prone to appear on the northward facing part where sunlight is the weakest. Once moss begins to build up, it will start to grow under the shingles and push them upward. Thick moss will also hold in more moisture. With the roof covered in moss and shingles buckled up, the moisture can invade your home to cause rot and decay.

Moss is a type of non-vascular plant. Unlike most plants that collect water through their root systems, moss gets its water through its leaves. So, in order for it to survive, it needs a moist environment. In the U.S., moss often grows on roof planes facing North that don’t receive as much direct sunlight, causing them to stay damp longer. Animals and wind can also carry moss spores which easily spread around the neighborhood.

While having a thick, lush layer of moss on your roof may look rustic and cozy, it can harm the elements of a premium roof and shorten its lifespan dramatically. If you notice a lot of moss hanging around atop your home, you’ll want to eliminate it as best you can to avoid requiring a roof tune-up. Here are some ways to remove moss from your home and keep it from coming back.

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man cleaning moss off shingles

Remove Moss from Shingles

There are several ways to remove moss from the shingles. The method you select will depend on the state of the existing roof system, the amount of work you want to place into the task, and your budget. One of the simplest, and messiest, ways to remove moss is to scrub it off. Also, take into account the height and architectural complexity of the roof, as you will need to use a ladder to get up high to treat the problem.
To avoid re-roofing earlier than you expected, try these methods to keep moss off your roof.

Perform a Scrub

Place a ladder carefully next to the moss growth area. Put on protective equipment like:

  • Old clothing
  • Slip-resistant shoes
  • Eye protection
  • Rubber gloves

You might even want to use a safety rope to secure yourself. Hose the area off by spraying at a downward angle with plain water.

Use a soft-bristled, long-handled scrub brush to scrub the moss off the roof. Scrub from the top of the roof down so you don’t lift any shingles. Be sure you’re rubbing gently and not scouring, scraping, or pounding on your roof. Scrub one small area at a time to prevent cracking, ripping, or ripping the shingles.

If scrubbing your roof doesn’t remove the moss effectively, there is a large range of cleaning solutions and do-it-yourself options you can try to eliminate your moss and roof problem.

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Use Dry Moss Killers

You apply the powder by sprinkling it in several lines parallel to your home’s ridge. Space each line around five feet from the next. Once it rains, the rainwater will mix with the dry powder and run down the roof toward the eaves. The moss should be gone after around a week.

Use Liquid Moss Killer

This comes in a container you attach to your garden hose. As the water flows, it mixes on a metered basis. If you have enough water pressure to reach your roof’s ridge, you can apply a liquid moss killer from the ground. Since it could be hard to track your progress, you may want to section out segments of your roof mentally and spray each section before you move onto the next one.

Man removing moss from the roofUse Chlorine Bleach and Water

Use a 50/50 mix of liquid chlorine bleach and water to clean moss effectively from your roof. Use a sprayer to apply the solution and let it sit on the surface of your roof for at least 15 minutes before rinsing it off. Use low-pressure water to rinse it off.

While you may need to extend dwell times, don’t let the solution dry completely because this could make it difficult to rinse the solution off completely. Protect your landscaping and other areas from the solution and wear appropriate protective equipment such as rubber gloves and eye protection.

The moss will start loosening up over time and you can remove it with a leaf blower. It might take a couple of bleach treatments in severe cases to remove all the moss. Don’t use a pressure washer for cleaning an asphalt shingle roof since this can lead to granule loss and premature roof system failure.

If you notice a lot of moss hanging around atop your home this is a potential warning sign, you’ll want to eliminate it as best you can to avoid requiring a roof tune-up

Preventing New Moss Growth

Fortunately, you can take preventative measures to keep moss off your roof. Keep your gutters free from debris, trim any branches that hang over your roof, and remove moisture collectors regularly like:

  • Branches
  • Seedpods
  • Leaves

These can pile up on your roof and promote moss growth.

A good long-term solution for preventing moss is attaching zinc-coated metal flashing strips or zinc strips (Z-Stop) right below the roof’s ridge caps or peak. When it rains, the water will flow over the strips and leach out the zinc particles which then attach to the tiles or shingles of your roof and stop new moss growth.

Working smart, safe, and strategically can almost guarantee your moss-removal efforts will be effective, and taking preventative measures means you can stay off the roof for many seasons to come.

Replace the Roof

Based on the state of the roof, you may simply replace the entire roofing system. This strategy is ideal if your roof has overall damage or when the shingles have reached the end of their lifespans. If the roof is still in good shape, then you can clean the moss off using these other methods.

Prepare Foundation Plants and Roof for Cleaning

Before selecting a cleaning method, you want to wet all plants, flowers and bushes along the foundation. This makes it easier for the moss to slide off once you toss it over the roof. You can also cover over the plantings using plastic sheeting. After the cleaning, make sure to wash off the moss that may have collected on the plantings.

DIY Cleaners

If the moss is stubborn and parts of it can’t be removed with a scrub brush, you can make a homemade cleaner. Mix 2 gallons of water with one of these household cleaners: 8 ounces of mild dishwashing liquid, white distilled vinegar (1 and a half to 3 and a half cups), or 1 cup of oxygen bleach. On a cloudy day, wet down the roof and apply the cleaner. Let it sit for 40 minutes before scrubbing the roof and rinsing it off.

Commercial Cleaners

There are also dry and wet commercial cleaners available. Some of these cleaners can be applied without rinsing them off. Instead, the rain will mix with the cleaner and remove it as well as the moss from the shingles.

Some common types of commercial cleaners include Bayer 2-in-1 Algae and Moss Killer, Wet & Forget, and Moss B Ware. Before using any cleaner, make sure to read and follow the manufacturer’s instructions for proper application. You will want to protect your plantings and other outdoor structures before applying the commercial cleaners.

Avoid Using Power Washers

It is true that you could use a power washer to blast the moss off the roof. However, high water pressure could further damage shingles that are already chipped or worn out. The water blast can also strip off the shingle’s granules that help protect your roof from adverse weather. If you decide to use a power washer, use the lowest pressure setting and stand at the top of the roof to wash the moss downward.

Prevent Moss from Returning

Once the moss is removed, consider adding copper or zinc strips to the top ridge of the roof. These metals naturally kill off algae and moss. You should also prune tree limbs so that more sunlight can reach the shingles.

Contact Dominion Roofing for Your Roofing Needs

Dominion Roofing offers a wide range of residential and commercial roofing services throughout Toronto and surrounding areas. From roof tune-ups to re-roofing, we have you covered! Contact us at 416-789-0601 or complete our online form.


Is it bad to have moss growing on your roof?

Moss is greenish miniature plants with a woodland appearance that grows in shady areas of the roof and can actually damage the roof. It’s bad to have moss growing on your roof as it can severely damage the structural integrity of the roof. Moss is also an indication of moisture which when gets beneath the tiles leads to wood root and leaks. Moss also harbor bugs and rodents which are a nuisance.

Should you remove moss from roof?

Yes! You should try and remove moss from your roof to prevent them from damaging your roof. There are several ways to remove moss from the shingles. The ideal method is usually dependent on the state of the existing roof system, your budget, and the amount of labor required done to remove the moss. You should be keen to spot and remove moss early enough before the roof gets severely damaged.

Does vinegar kill moss on roofs?

Yes? Vinegar is quite effective in killing moss and lichens. This is because vinegar contains chemicals such as chlorine which are acidic and kills living plants. Just mix 1½ to 3½ cups of white distilled vinegar with 2 gallons of water and pour it on moss. Leave it to soak for up to 24 to 48 hours. The use a brush to remove the dead moss or lichens

Does baking soda kill moss on roofs?

Baking soda can kill moss on roofs. Moss dies when it is exposed to alkaline, which is why this solution works so well. But you do need to be careful when using it, especially if you have new cedar shingles. If the solution gets onto the bare shingles, it will cause them to fade very quickly.

What can I put on my roof to stop moss growing?

Laying copper or zinc strips along the roof ridge is a good way to stop moss growing. A 2-inch strip is wide enough to keep the average-sized roof moss free. Cutting back trees and plants that overhang your roof will also help. It will make the roof too hot for moss to grow freely.

Will bleach damage asphalt shingles?

Provided you do not use bleach too often it will not damage asphalt shingles. It is important to dilute it properly. Mixing 1.5 cups with 3 cups of water is sufficient to remove most roof staining. Also, you should only use oxygen bleach. The chlorine type is too strong.

How to kill moss on roof?

A layer of green moss might look cozy but it can be bad news for your roof. The following steps can be followed to clean it and prevent it from coming back. Firstly, hose off and brush all moss loose from your roof shingles working one small area at a time then apply a store-bought or DIY cleaning solution to remove the moss using a soft-bristle brush. Lastly, install Copper or zinc on the roof to prevent future moss growth.

How to get rid of moss on a roof?

Moss can cause roofing to degrade thus the importance to get rid of it. You can physically remove it using a long-handled scrub brush without overdoing it. Work down the roof to avoid breaking or lifting shingles. There are several chemicals on the market specifically made to kill moss. Diluted bleach will work well but be sure to wear protective clothing. Lastly, install strips of copper or zinc to prevent moss from coming back.

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