How to Remove Moss From Your Roof: A Complete Guide (2024)

Why Removing Moss From Your Roof Is Important

Moss grows on areas of your roof that receive minimal sunlight, so northern-facing roofs and parts of the roof that are shaded are particularly vulnerable. Moss begins growing on the surface of your roof shingles, but as it expands, it can penetrate under the shingles, eventually pushing them upward. This can cause several problems, which we’ll review with you below.

Property Damage

First, uplifted roof shingles make your roof system more prone to water leaks, as precipitation can more easily get under the protective layer. Second, moss naturally retains water, so excessive growth can mean your roof shingles and underlayment are more regularly exposed to moisture, making them more likely to leak or rot. This can significantly shorten the life of your roof.

If water or moisture are making their way under your roof shingles, you’re more likely to experience these problems over time:

• • • • Decomposing shingles and roof underlayment
      • Water intrusion into your living space
      • Wet or water-damaged wood and insulation
      • Reduced energy efficiency due to damaged insulation and increased indoor humidity
      • Less comfortable living space due to higher humidity levels
      • Compromised electrical system
      • Indoor mold growth and reduced indoor air quality

If moss is allowed to grow unchecked, resulting problems can quickly become severe. In some cases, the repairs can run you thousands of dollars — you may even be looking at total roof replacement.

Moss and Gutter Systems

Unfortunately, moss and lichen can cause your gutters and downspouts to clog more easily, meaning you’ll need to clean the gutters more frequently if moss is growing on your roof. Clogged gutters can shorten the gutters’ lifespan and lead to other problems like foundation damage and interior leaks.

Issues With Moss and Solar Panels

Another issue you’ll run into with moss growing on your roof is that it can prevent you from installing solar panels.

If you’re looking into installing solar and an installation company comes to survey your property, they’ll inspect your roof for signs of damage or developing problems, including moss growth. In many cases, moss will need to be treated before solar panels are installed. In the worst-case scenario, the moss might mean you need a full roof replacement before solar panels can safely be installed.

Problems With Energy Efficiency

The effect moss has on your roof can decrease your home’s energy efficiency.

Roof shingles are insulative, and when they’re displaced by moss growth the space created allows for more heat transfer between your living space and the outside air. More heat will escape your home in the winter, and more cool, conditioned air will escape in the summer. 

In response to less comfortable indoor temperatures, homeowners will tend to increase the demand on their heating and cooling systems, placing more strain on the environment.

Additionally, moss will hold water against your roofing materials, giving water or moisture more opportunity to enter your living space and make indoor air humid. Increased humidity makes your indoor air feel less comfortable, leading to turning up the AC or heating system.

Overall, moss is detrimental to your home’s energy efficiency, so removing it can reduce your energy bills and have a positive effect on the environment overall.

How to Remove Moss From Your Roof

Now that you understand the importance of removing moss from your roof, we’ll explain how it’s done. Luckily, the process is an ideal DIY home improvement project, so with minimal monetary investment and some safety precautions, you can remove your roof moss yourself.

Below is a list of things you’ll need:

• Roof moss killer (from Home Depot, Lowes, Amazon or other home improvement supply source)
• Ladder
• Hose
• Putty knife or soft-bristle scrub brush (do not use a wire brush)
• Roof harness (recommended for safety)

Once you’ve gathered your materials, you can follow the steps below to remove the moss from your roof.

Step 1: Apply the Roof Moss Killer

Your first step will be to apply the roof moss killer. We’ll explain how to do it with both types available (dry and liquid) below.

Using Dry Moss Killer

If you purchased dry moss killer, get up on your roof and begin the application process at the roof ridge. It’s best to apply it in horizontal lines running the length of your roof spaced about two feet apart, working from top to bottom. You can now move on to step two below.

Using Liquid Moss Killer

Liquid moss killer comes either pre-mixed in an applicator, or as a liquid concentrate or powder that you mix with water in a garden sprayer. In any case, apply the moss killer in an even coat across the entire roof, moving from the eaves down toward the fascia and soffits.

Liquid moss killer is already wet, so you can skip over step two and go directly to step three if you’ve opted for a liquid application.

Step 2: Wet the Roof

This step is only necessary if you use dry moss killer. Once you’ve laid down the product, you can either wait for a light rain or, to proceed right away, dampen the roof with a garden hose.

You’re looking for a light sprinkling from your hose to avoid washing away all of the product. Begin at the top and aim for even application with minimal runoff into your gutter system. Once the entire roof has been dampened, leave the moss remover to work based on the manufacturer’s recommendation.

Step 3: Wait for the Moss Killer to Take Effect

Moss killers are effective, but they take time to work. You might need to wait anywhere from one to four weeks for the moss to die off. Over that time you’ll notice the patches of moss turn brown and start to look flaky. At this point, you can proceed to step four.

Step 4: Scrub Away the Dead Moss

Once you can see that the moss has died, it’s time to get back up on your roof and remove it. We recommend using a putty knife around roof penetrations (such as holes in your roof made to install pieces of equipment) and a soft-bristle brush on the shingles.

It might be tempting to use a wire brush or something similar to speed up the process, but more abrasive tools can damage your roof, pull away asphalt granules and lead to more leaks or other issues. We strongly recommend using a soft-bristle brush only.

The removal process is time-consuming, but it’s the best way to ensure you get rid of the problem completely and reduce the risk of roof leaks.

Step 5: Rinse and Repeat

Finally, rinse off the debris you scrubbed away with a garden hose. You can repeat the entire process if needed, but this should only be required if you had a very severe roof moss issue to begin with.

Types of Moss Removal Products

As we discussed above, there are two primary types of moss killers: liquid and dry. In terms of efficiency, the two types are more or less identical. However, there are some differences when it comes to cost, ease of application and shelf life. We’ll discuss these differences below.

What Are Dry Powder Moss Killers?

Dry powder moss killers are, as the name implies, dry powders that you apply directly to your roof. Since this product comes in powder form, the shelf life is more or less infinite, so you can buy in bulk to save and just use it as you need it.

Dry moss killers take a bit more time and work for you, as you need to spread the product on the roof and then apply water with a hose. You’ll also need additional equipment, like a garden sprayer.

However, dry moss killers do have the benefit of costing significantly less — about half the price — of liquid moss killers.

What Are Liquid Moss Killers?

Liquid moss killers often come pre-diluted, which means they are ready to apply straight from the container. They typically come in a spray bottle or in a container that you can attach a hose to for easy application.

Liquid moss killers don’t have as long a shelf life as dry ones, so it’s best to get only the amount you need for one application. However, the process of applying it is simpler and doesn’t require any additional equipment.

Liquid moss killers are more convenient, so you can also expect them to be more expensive.

What Are the Best Moss Removal Products?

There are many different roof moss killers available from your local home improvement store or on Amazon, so it can be difficult to sort through them and figure out which ones will work best.  Some of our top picks for moss killers include:

• Homemade moss removal products
• Lilly Miller Moss Out! For Roofs & Structures
• BioAdvanced Moss & Algae Killer & Cleaner
• Scotts MossEX 
• Corry’s Moss B Ware

Vinegar

Vinegar is an all-natural, cost-effective way to safely kill moss. It contains the natural ingredient acetic acid, a natural moss remover. Simply fill a spray bottle with distilled white vinegar, diluted with some cold water. Apply the solution daily until the moss dies. Depending on the strength of the moss, you may need to use a stronger product below.  

Lilly Miller Moss Out! For Roofs and Structures

Moss Out! For Roofs and Structures from Lilly Miller is a dry moss killer that is affordable and super effective. Although it demands a bit more work from you than a liquid moss killer, the results are outstanding, and you’re more likely to have to wait just a week or two for the moss to die rather than a month as you might with some other products.

BioAdvanced Moss & Algae Killer & Cleaner

This moss killer comes in liquid form in a convenient spray bottle, so there is minimal preparation required from you. You just need to make sure your roof is dry and safe to walk on, and this product will be a breeze to use to clean off moss. It’s especially convenient for cleaning moss from small areas of moss growth.

Scotts MossEX

MossEx from Scotts is a dry moss killer that is really designed for killing moss in or near your grass or around your landscape features. However, you can apply it as a roof cleaner without worrying about the runoff killing the grass or plants below.

Corry’s Moss B Ware

Corry’s Moss B Ware is another dry formula that is easy to apply and is super effective. It won’t stain or corrode your asphalt or metal roof or gutters. Just make sure to take extra precautions when using this product, as it is a skin and eye irritant.

Are There Natural or Eco-Friendly Ways to Remove Roof Moss?

Some moss killers available from hardware stores and online aren’t the best for the environment, but unfortunately, there are no all-natural products that work quite as well.

Some websites recommend using chlorine bleach or dish soap for roof cleaning, but these products are also not great for the environment and don’t work well for roof moss removal. The best thing you can do is mitigate the damaging effects the dedicated moss killer products have on the ecosystem.

One thing you can do to protect the environment while using moss killers: disconnect your downspouts and route any runoff to your lawn. This will help keep the chemicals out of storm drains and prevent them from contaminating water bodies and drinking water.

You can also choose more environmentally friendly products, like those that don’t contain zinc or copper. Zinc and copper are toxic to many animals, so choosing a product without them is a good option overall, especially if you have pets or children in your home. Sodium percarbonate is an effective and environmentally friendly moss remover contained in some of the products we outline above.