• Cleaning: 2 – 3 Hours
  • Drying: 1 – 2 Hours
  • Difficulty: Medium
  • Cost: Medium

Mold is a menace that can plague warm and humid spots of your home. It can show up as dark-colored spots or black stains. The warmth and humidity trapped in your roof make it vulnerable to mold, mildew, moss, and algae growth. 

Houses located in states prone to flooding or wet climates are at a higher risk of developing mold. Mold can affect the exterior appearance of your home and can even penetrate into the structure of your home if ignored. 

Mold isn’t just unsightly but can cause persistent health issues such as difficulty breathing and headaches. It can also be hazardous for people with asthma.

While the most common solution to eradicate mold growth is by calling experienced professionals, you’re able to affordably and effectively remove mold stains and spots from roof shingles yourself with a little bit of elbow grease. 

1. Prepare the Cleaning Solution 

The main items you will need to clean mold from your roof can be easily found in your home. Heavy-duty bleach is a household item you will need for preparing the cleaning solution, bleach is a powerful ingredient that effectively kills and removes mold. 

mold growth on roof shingles
Roof Shingles Plagued by Mold Growth

An additional item, dishwashing liquid or dish soap, is not vital but can help make your roof look cleaner and increase the viscosity of the cleaning solution for easier application. 

You will also need to use a gallon sprayer for this process, it’s helpful in dispersing the cleaning solution and achieving maximum coverage for your roof shingles. You can use a normal spray bottle but multiple refills will be necessary depending on the size of your roof. 

Bear in mind that power washers are too harsh for roof shingles and can affect the quality of your roofing. Using power washers for your roof can also reduce the lifespan of roof shingles and cause leaks. 

Mixing the Cleaning Solution

The formula for the cleaning solution consists of equal parts of hot or warm water and bleach. If you have a sprayer that has a one-gallon capacity, you should add ½ a gallon of hot or warm water and ½ a gallon of bleach. 

Add a bit of dishwashing liquid to the cleaning solution, about 1 ounce for relatively flat roofs, and up to 4 ounces for very steep roofs. The addition of dishwashing liquid makes it more viscous and helps to set the cleaning solution a little when you apply it to the roof. 

We recommend using gloves and eye protection to keep yourself safe from bleach during this process.

Bleach-Free Alternative Cleaning Solutions For Removing Moss From Roof Shingles

If you prefer not to handle bleach or use bleach on your roof, we have two popular bleach-free alternatives we recommend:  

  1. Wet & Forget Outdoor Cleaner – This bleach-free and non-acidic cleaner removes signs of mold, mildew, moss, and algae from your roof shingles. It is an excellent cleaner that not only removes impurities from your roof but also prevents staining for up to a year. It also comes with a sprayer, making it ready to use. This is ideal for small outdoor surfaces. 
  2. Spray & Forget Roof Cleaner Concentrate – This roof cleaner is truly revolutionary as it removes all signs of algae, mold, and moss from your roof efficiently. You don’t need to rinse your roof after application, and it can cover 1,000-2,000 square feet after mixing the concentrate with water. 

Both of these roof cleaners (and also similar ones) are safe to use on multiple types of roof shingles, such as asphalt shingles, wood shingles, slate shingles, and clay or tile shingles.

2. Protect the Surrounding Areas of the Roof 

The next step after preparing the cleaning solution is to protect the surrounding areas of the roof. Bleach is a harmful chemical agent that can destroy vegetation and plants. If you want to protect the surrounding areas, especially the greenery in your garden, you should cover these areas with plastic sheets or a tarp. 

This will ensure you can clean your roof shingles effectively without much damage. It is also best to keep small children and pets inside while you work on the roof, to keep them safe from bleach and dangerous chemicals.  

3. Get on Top of the Roof 

Getting on top of the roof and cleaning it involves some risk, so you’ll need to be careful! You need to safely get on top of the roof with a ladder or find a tall and safe spot to spray the cleaning solution onto your roof. Consider wearing a safety harness and other protective equipment for the task. 

Wear a respirator mask that filters out mold spores, as this will prevent the inhalation of mold spores, and help you breathe without irritation. Exposure to a large number of mold spores can cause a variety of health problems. 

Slip-resistant shoes can also help you navigate the roof without slipping. If you are working on a large roof, you should have some emergency tools and a cell phone with you, in case you get stranded.

4. Remove Mold Stains From Roof Shingles 

After following these precautionary measures, it is time to begin removing mold from your roof shingles. The first step in the process is to sweep your roof free of dirt, dust, and excessive growth of mold with the use of a broom. 

This will help you remove mold more effectively with the cleaning solution and reduce the time you spend removing heavy mold growth. It is essential to wear a respirator mask when scrubbing the heavy mold growth on your roof so you can stay safe from mold spores in the air. 

Applying the Cleaning Solution

The next step in the process is to clean the roof shingles. We recommend starting from the lowest row of shingles and working your way toward the top. This application method prevents drainage in your direction and allows you to clean efficiently. Spray the roof shingles until you notice runoff. 

After spraying the entire roof, let the chemicals work their magic on your roof for about 20-30 minutes. The porous parts of your roof may absorb and soak in some of the cleaning liquid and begin killing the attached mold. 

Always check the weather before cleaning your roof. A heavy downpour can wash off the cleaning solution before it has time to do its work and light rain can dilute the applied bleach solution, rendering it ineffective for mold removal.

Letting the Solution Rest

After having applied the cleaning solution and you’ve let it rest for about 20-30 minutes, you need to properly rinse the entire roof with water. If you do not rinse your roof with water after the cleaning process, the bleach in the cleaning solution might permanently discolor or damage your roofing. 

Mold takes time to completely go away after you apply and rinse off the bleach cleaning solution. Your roof may actually look worse before it gets better, the mold will disappear slowly after bleaching it. It may even look yellow right after bleaching. 

It can take several weeks to several months for the mold to be completely removed from your roof shingles. 

Best Practices for Prevention and Maintenance 

Here are some best practices you should keep in mind for removing mold from roof shingles to achieve the best results.

  • Clean Gutters Frequently – When you clean your gutters frequently, there is a lower chance of debris buildup, as well as moss and mold growth. Cleaning your gutters can also help you spot any mold problems early on. 
  • Get Rid of Standing Water – Mold mainly grows due to trapped moisture, which is why you should remove any standing water from your roof as soon as possible. This way, you can ensure that the standing water doesn’t cause algae, moss, or mold growth.
  • Trim Tree Branches – Overhanging tree branches can promote mold and moss growth on asphalt roof shingles. The spores from tree branches can land on the roof and begin causing algae, moss, or mold growth. 
  • Avoid Using Harsh Chemicals & Power Washers – A higher concentration of bleach, harsher chemicals, or power washers can leave your roof vulnerable to further damage. Harsh chemicals can affect the appearance of the shingles, while power washers cause your roof to begin leaking or dislodge your roof’s shingles.
  • Install Zinc or Copper Flashing – By installing zinc or copper flashing on your roof, you can prevent mold, mildew, moss, and algae. Zinc and copper strips enhance the durability of your roof and inhibit mold growth.  
  • Switch to Mold-Resistant Roof Shingles – Prevention is better than cure. This is why it is better to opt for a mold-resistant, yet costly roofing option, than to clean your roof yourself or hire a professional to remove mold. 

Frequently Asked Questions 

Below, you’ll find some common questions that are frequently asked by homeowners that deal with removing mold from their roofs. We have answered them to help you understand how to clean roof shingles in the best way possible.

How Frequently Should I Remove Mold from Roof Shingles? 

The frequency of cleaning your roof depends on the kind of mold damage on your roof. It is best to inspect your roof before cleaning it to see how diligently it needs to be cleaned to remove mold growth. 

We recommend cleaning your roof once or twice a year, depending on how severe the mold growth is on the shingles. Aim to clean your roof annually to keep it in good condition and prevent buildup, aim for at least twice a year if there is serious mold growth. 

How Long Does It Typically Take to Remove Mold from My Roof?

It typically takes a few hours to clean your roof, this will depend on the size of your roof. The smaller the roof, the less time you will require. Once you have rinsed the entire roof, allow it to dry for a couple of hours. After a few weeks or months, you will begin noticing that your roof is free from mold.