Why Is My Roof Growing Moss? (9 Ways to Get Rid of It)

The roof of your home is one of the most important parts of your house. They protect you from rain, snow, and other weather elements.

But what happens when that roof starts to grow moss? Are you looking at a serious problem for your home?

Let’s talk about why moss grows on roofs and what you can do to get rid of it.

Why is my roof growing moss?

Your roof is growing moss because it’s probably been damp for long periods of time.

Moss likes to grow in damp, shady places. If your roof doesn’t get a lot of sunlight and it stays damp for a long time, that’s the perfect environment for moss to grow.

Moss can hold moisture against your roof, which can cause damage over time.

To prevent moss from growing on your roof, you can make sure your roof gets more sunlight by trimming any nearby trees or bushes that are blocking it.

You can also make sure that your roof is free of debris like leaves and branches, which can trap moisture and make it easier for moss to grow.

Why does your roof have moss?

Poor drainage

If your roof doesn’t have proper drainage, water can collect on the surface and lead to excess moisture. As we’ll talk about below, moss grows because there is too much water.

Excess moisture

Moss thrives in damp environments, so if your roof is frequently wet or moist, this can encourage moss growth. As we already said, too much water on your roof can be caused by problems with drainage and ventilation.

Poor ventilation

If your roof doesn’t have proper ventilation, it can trap moisture and heat, which can also contribute to the growth of moss.

Lack of sunlight

Moss prefers shady environments and doesn’t grow as well in direct sunlight. If your roof is in a shaded area or has a lot of tree cover, this can create an ideal environment for moss to grow.

Poor roof maintenance

If your roof isn’t cleaned or maintained regularly, debris can build up and trap moisture, which makes it a good place for moss to grow.

Moss-friendly shingles

Certain types of roofing materials, such as cedar shakes, are more susceptible to moss growth than others. Moss can latch onto rough or porous surfaces, so shingles that have a lot of texture or grooves may be more susceptible to moss growth.

Presence of nutrients

Moss requires certain nutrients, such as nitrogen, to grow. If there are sources of nutrients on your roof, such as bird droppings or decaying leaves, this can encourage moss growth.

Moss spores

Like other plants, moss reproduces through spores that can travel through the air. If there are moss spores in the area, they can settle on your roof and start to grow.

Plant growth stimulants

Certain fertilizers or other plant growth stimulants that you use in your yard or garden can also encourage the growth of moss on your roof.

Growth of algae

Algae can also grow on roofs and create a moist environment that encourages moss growth. Algae can also create a food source for moss, so if there is algae present on your roof, this can increase the likelihood of moss growth.

What are the dangers of having moss on my roof?

  • Damage to shingles: Moss can grow into the tiny spaces between shingles and lift them up, leading to damage or even leaks in your roof.
  • Increased weight: Moss can retain moisture, which can make your roof heavier and potentially lead to structural damage.
  • Reduced lifespan of your roof: If moss is allowed to grow unchecked, it can contribute to the deterioration of your roof over time, potentially reducing its lifespan.
  • Water damage: Once moss has damaged the shingles on your roof, water can seep in, causing rotting, mold growth, and other types of water damage.
  • Structural damage: Water damage caused by moss growth can also lead to structural damage in the roof and the underlying support structures such as the wall of your house.
  • Increased risk of ice dams: In cold climates, moss can contribute to the formation of ice dams, which can damage your roof and cause leaks.
  • Decreased energy efficiency: Moss growth can block sunlight from reaching your roof, which can reduce the effectiveness of solar panels or other energy-efficient technologies.
  • Risk of slips and falls: If you or a professional need to climb onto your roof to perform maintenance or remove the moss, the growth can create a slippery surface that increases the risk of slips and falls.
  • Decreased curb appeal: Moss growth can create an unsightly appearance that can decrease the overall value and curb appeal of your home.
  • Risk of mold growth: If moisture is trapped under the moss, it can create an environment that is conducive to the growth of mold, which can be a health hazard for you and your family.

Best ways to get rid of the growing moss on your roof

Method 1: Clean the moss off the roof

One effective way to remove moss from your roof is to physically scrape or brush it off.

This can be done with a long-handled scrub brush or a specially designed moss scraper.

Be sure to take safety precautions and use protective gear such as slip-resistant shoes, a safety harness, and safety goggles.

Method 2: Clean the moss off the sides of the house

If the moss has spread to the sides of your house, it’s important to remove it from those surfaces as well.

Use a scrub brush and cleaning solution to gently scrub away the moss. Be careful not to damage any paint or siding in the process.

Method 3: Use a moss preventative treatment

To stop moss from growing in the first place, you can treat your roof with a moss preventative.

Most of these treatments have zinc or copper particles in them that stop moss and algae from growing. They can be sprayed or rolled onto the surface of the roof.

Method 4: Spray the roof with bleach or a chlorine bleach solution

Bleach or a chlorine bleach solution can be an effective way to remove moss from your roof.

Mix one part bleach with three parts water and apply it to the roof with a spray bottle. Be sure to take safety precautions and use protective gear.

Method 5: Spray the moss with cleaning solutions

There are many ways to clean your roof and get rid of moss, such as using vinegar, hydrogen peroxide, or commercial products made for that purpose.

Apply the solution to the affected areas and let it sit for a few minutes before rinsing it off.

Method 6: Use a power washer to remove the moss

A power washer can be a quick and effective way to remove moss from your roof.

But be careful that the high pressure doesn’t damage your shingles or other roofing materials.

Use a low-pressure setting and keep the nozzle at least six inches away from the roof surface.

Method 7: Apply a mineral granule coat to the roof

Putting a coat of mineral granules on your roof can help stop moss from growing by making the surface less friendly to moss and algae.

This can be a good solution for roofs that are difficult to clean or maintain.

Method 8: Use baking soda

Baking soda can be an effective, natural way to remove moss from your roof.

Mix one part baking soda with one part water and apply it to the moss. Let it sit for several hours before rinsing it off.

Method 9: Use Dawn dishwashing soap and vinegar

This combination can be a very effective solution to removing moss from your roof.

Mix a cup of vinegar, a cup of water, and a half cup of Dawn dishwashing soap (or any size 1:1 ratio of the two) in a spray bottle.

Spray the mixture on the affected area and let it sit for 15 to 20 minutes before rinsing it off with water.

How to prevent the growth of moss on your roof in the future

  • Keep your roof clean with regular cleanings: Regularly cleaning your roof is one of the best ways to prevent moss from growing on it. You can use a broom or leaf blower to remove debris, and clean it with a low-pressure washer or a mixture of water and mild detergent.
  • Use a moss-proof roofing material: Certain types of roofing materials, such as metal or asphalt shingles with zinc or copper granules, are resistant to moss growth. Consider using these materials when replacing or installing a new roof.
  • Make sure there is sufficient drainage on your roof: Water that accumulates on your roof can promote the growth of moss. Make sure your roof has proper drainage and install gutter systems that direct water away from your roof and your home’s foundation.
  • Make sure there are no holes or leaks in your roof: Holes or leaks in your roof can allow moisture to seep in, providing a hospitable environment for moss growth. Check your roof regularly for any damage and repair it promptly.
  • Spray your roof with a moss killer spray: Spraying your roof with a moss killer spray is a good way to prevent moss from growing. These sprays typically contain zinc or copper particles that inhibit the growth of moss and algae. Follow the instructions on the product label carefully.
  • Remove the shade that’s covering your roof: Moss thrives in damp, shady environments, so removing or trimming trees or other vegetation that casts shade on your roof can help prevent moss growth.
  • Keep your gutters clean: Clogged gutters can trap water on your roof, promoting moss growth. Make sure to clean your gutters regularly to prevent debris buildup and ensure proper drainage.

What types of roof materials are prone to moss growth?

Type of roofing shinglesMoss growth preventionWhy?
Metal roofsGoodGenerally less prone to moss growth, unless in shaded areas or with accumulated debris.
Slate roofsGoodResistant to moss growth, but can still be prone to it in damp or shaded locations.
Clay and concrete tilesFairNot organic, but still prone to moss growth in shady or damp locations.
Rubber roofingFairCan develop a rough, porous surface that traps dirt and debris, creating a favorable environment for moss spores to grow.
Asphalt shinglesPoor/fairMade of organic materials that provide a good environment for moss to grow.
Wood shingles and shakesPoorAlso made of organic materials and can retain moisture, making them more susceptible to moss growth.
Here’s a table ranking the best type of roofing shingles to use when you want to avoid moss growth. Keep in mind that no roofing material is naturally immune to growing moss. Moss can grow on almost any surface if the right conditions hold up.

Asphalt shingles

Asphalt shingles are one of the most common types of roofing materials, and they are also one of the most susceptible to moss growth. This is because they are made of organic materials that provide a good environment for moss to grow.

Wood shingles and shakes

Wood shingles and shakes are also organic materials and can provide a good environment for moss growth. In addition, they can retain moisture, making them more susceptible to moss growth.

Clay and concrete tiles

While clay and concrete tiles are not organic materials, they can still be prone to moss growth, particularly if they are in a shady or damp location.

Metal roofs

Moss tends to grow less on metal roofs than on other kinds of roofs, but it can still happen in some situations. For example, if they are in a shaded area, debris can accumulate on the surface and create a favorable environment for moss growth.

Slate roofs

Slate roofs are also relatively resistant to moss growth, but they can still be prone to it if they are in a damp or shaded location.

Rubber roofing

Because of how they are made and what they are made of, moss can grow on rubber roofing shingles. Rubber shingles can create a rough, porous surface that can trap dirt and other debris. This makes it easy for moss spores to take root and grow on the roof. But some rubber roofing materials are made with a coating that keeps water from getting in. This may naturally stop moss from growing.

How often should I inspect my roof for moss growth?

It’s a good idea to inspect your roof for moss growth at least once a year.

If you live in a damp, humid climate or an area with heavy rainfall, you may want to consider inspecting your roof more frequently, such as every six months.

Older roofs may also need to be checked more often because they may be more likely to get moss and have other problems.

During your inspection, look for any signs of moss growth, such as green or brown spots on the roof, as well as any signs of damage, such as missing shingles, cracks, or leaks.

If you notice any signs of moss growth or damage, it’s important to address the issue as soon as possible to prevent further damage and potentially costly repairs.

How long does moss take to grow on a roof?

Moss can start to grow on a roof in as little as six months and for up to two years, particularly in damp, shaded areas. However, it may take as long as 5 to 6 years for moss to become noticeable and for a significant amount of growth to occur.

Once moss has taken hold on a roof, it can spread quickly and cause damage if left untreated.

It’s important to address moss growth as soon as it’s noticed to prevent it from getting worse and causing more extensive damage to the roof.

Regular roof maintenance, like keeping the roof clean and free of debris, and preventative measures, like using a roofing material that doesn’t grow moss, can help keep moss from growing on your roof and make it last longer.

Is it OK to have moss growing on your roof?

One unique aspect of moss growth on a roof is that it can attract pests such as rodents, insects, and birds.

These pests may be drawn to the damp environment created by the moss and may make nests or burrows in the roof structure.

This can lead to further damage and potential health hazards, as the pests may carry disease or create fire hazards.

Also, the weight of the moss can add stress to the roof, which can cause it to sag or even collapse over time.

What should I not do to remove moss from my roof?

  • Do not use a pressure washer: While pressure washing can be an effective way to remove moss, it can also cause damage to your roof by dislodging or loosening shingles, stripping granules from asphalt shingles, and forcing water underneath the shingles.
  • Do not use harsh chemicals: Bleach and other harsh chemicals can damage your roof and kill surrounding plants and vegetation. In addition, the chemicals can be harmful to the environment and potentially hazardous to human health.
  • Do not scrape or scrub the moss off: Using a scraper or brush to remove moss can be tempting, but it can also cause damage to your roof. This method can loosen or dislodge shingles, and may also leave behind small pieces of moss that can quickly regrow.
  • Do not walk on the roof: Walking on the roof can be dangerous, as it can lead to falls and injury. In addition, the weight of a person can cause damage to the roof structure, especially if the roof is already weakened by moss growth.
  • Using metal tools: Metal tools such as a metal scraper or wire brush can scratch and damage your roof, especially if you have asphalt shingles. Instead, use a plastic scraper or soft-bristled brush to remove the moss gently. Metal tools can also increase the risk of electrical shock if they come into contact with power lines near the roof.

What time of year does moss grow on roofs?

Moss can grow on roofs at any time of the year, but it tends to be most prevalent in areas with high humidity and moisture, such as in the spring and fall.

In these seasons, there tends to be more rainfall, which can create the damp conditions that moss thrives in. However, moss can grow on roofs year-round if the conditions are right.

In fact, moss is known to thrive in moist and shaded environments, which are often found on rooftops with overhanging trees or other sources of shade.

How much does it cost to remove moss from a roof?

How much it costs to remove moss from a roof depends on a number of things, such as the size of the roof, the amount of moss, where the roof is, and how it is removed.

The cost to remove moss from a roof can vary depending on factors such as the size of the roof, the extent of the moss growth, and the location of the property. Generally, it can cost between 20 cents and 70 cents per square foot to have a professional cleaning company remove the moss.

Some do-it-yourself methods, like using cleaning products or preventive treatments, can be cheaper, but the cost of materials and tools will vary. It’s important to note that the cost of removing moss is relatively low.

Moss removal companies use various methods to remove moss from roofs, depending on the type of roof and the severity of the moss growth.

These methods include manual removal, soft washing, pressure washing, and chemical treatments. To make sure the job is done safely and well, it’s important to hire a moss removal company with a good reputation and a lot of experience.

Companies will likely remove moss from your roof with a 50:50 solution of laundry liquid, chlorine bleach, and water or eco-friendly alternatives to remove moss.

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Author: Logan

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