Sodium percarbonate, a powerful oxidizing agent, is often considered the best chemical for washing a roof. When it comes to effectively removing stains, algae, and moss from a roof, sodium percarbonate offers unparalleled results. However, it’s important to understand the potential risks and proper application methods before using any chemical on your roof. In this blog post, we will explore the different types of chemicals commonly used for washing roofs, their benefits, and potential drawbacks to help you make an informed decision for your roof cleaning needs.

Key Takeaways:

Understanding Roof Types

Even though all roofs are designed to fulfill the same basic function of protecting the building from the elements, they come in different types and materials. Understanding the specific characteristics of each roof type is crucial for determining the best chemical for washing a roof.

Below is  a comprehensive breakdown of roofing types along with the materials commonly used in their construction:

Roof Type Material
Asphalt Shingle Asphalt, fiberglass, or organic materials
Metal Steel, aluminum, copper, or zinc
Tile Clay, concrete, or slate
Flat Asphalt, rubber, or PVC

Asphalt Shingle Roofs

Types of asphalt shingle roofs are common in many residential properties. They are known for their affordability, versatility, and ease of installation. Asphalt shingles can come in various colors and styles, making them a popular choice for homeowners.

When it comes to cleaning asphalt shingle roofs, it’s important to use a gentle yet effective chemical solution to avoid damaging the shingles or causing discoloration.

Metal Roofs

To understand the specific maintenance needs of metal roofs, it’s essential to recognize the different types of materials used, such as steel, aluminum, copper, or zinc. Metal roofs are valued for their durability, longevity, and resistance to weathering and corrosion. They are also known for their energy efficiency and environmentally friendly nature.

It is important to choose a chemical for washing metal roofs that is compatible with the specific metal material to avoid any corrosion or degradation of the surface.

It is essential to choose a chemical for washing metal roofs that is compatible with the specific metal material to avoid any corrosion or degradation of the surface.

Tile Roofs

To effectively maintain tile roofs, it’s crucial to understand the different materials they are made of, such as clay, concrete, or slate. Tile roofs are known for their aesthetic appeal, durability, and resistance to fire and insect damage. They come in a variety of colors, shapes, and textures, adding a unique charm to residential and commercial buildings.

Roofs made of tiles often require specialized chemical solutions that are gentle on the surface while effectively removing dirt, mold, and algae.

Flat Roofs

Flat roofs are commonly found in commercial and industrial buildings, and they are also used in some residential properties. They are characterized by their horizontal or nearly horizontal design, offering a unique aesthetic and functional appeal. Materials used for flat roofs include asphalt, rubber, or PVC.

Asphalt, rubber, or PVC are prone to damage from harsh chemicals, so it’s crucial to select a gentle yet powerful detergent for washing flat roofs.

Common Contaminants on Roofs

Not all roofs are created equal, and neither are the contaminants that can accumulate on them. Understanding the common types of contaminants found on roofs is crucial for determining the best chemical for washing a roof.

Algae and Moss

Moss and algae are common culprits when it comes to roof contamination. These organisms thrive in damp and shaded areas, which makes roofs an ideal environment for their growth. If left untreated, moss and algae can cause damage to the roof and compromise its integrity.

It’s important to address moss and algae growth promptly to prevent any structural damage to the roof. Regular cleaning and treatment can help control their growth and preserve the roof’s lifespan.

Mold and Mildew

With their ability to thrive in moist and humid environments, mold and mildew can be persistent problems for roofs. These contaminants not only detract from the aesthetic appeal of the roof but can also pose health risks to the inhabitants of the building. It’s crucial to address mold and mildew promptly to avoid any potential health hazards.

It is essential to choose a chemical for roof washing that effectively targets and eliminates mold and mildew, while also preventing their recurrence. Look for a solution that not only cleans the surface but also inhibits further growth of these contaminants.

It is important to closely examine the type of mold and mildew present on the roof before selecting a chemical for washing. Different types of mold and mildew may require different treatment approaches, so identifying the specific contaminants is crucial.

Dirt and Debris

Common contaminants such as dirt, dust, leaves, and other debris can accumulate on roofs over time, detracting from their appearance and causing potential drainage issues. Regular maintenance and cleaning are essential to prevent the buildup of dirt and debris, which can lead to clogged gutters and water pooling on the roof.

Any accumulated dirt and debris should be promptly removed to prevent any potential damage to the roof. A thorough cleaning with an effective chemical solution can help restore the roof’s appearance and functionality.

Any chemical used for washing the roof should be capable of effectively loosening and removing dirt and debris without causing damage to the roof’s surface or surrounding environment.

Staining from Trees and Other Natural Elements

Staining from trees, leaves, bird droppings, and other natural elements can detract from the visual appeal of a roof. These stains can also be indicative of potential underlying issues such as mold growth. It’s important to address these stains promptly to maintain the roof’s integrity and appearance.

Mold, mildew, algae, and dirt can contribute to the accumulation of stains from trees and other natural elements, making it essential to choose a chemical that effectively eliminates these contaminants while also lifting and preventing the recurrence of stains.

Chemical Solutions for Roof Washing

Your roof is constantly exposed to the elements and can accumulate dirt, grime, and even algae over time. To effectively clean your roof, you will need the right chemical solution. Here, we will discuss some of the best chemicals for washing a roof, their advantages, and their disadvantages.

Chlorine Bleach Solutions

With its powerful disinfectant properties, chlorine bleach solutions are commonly used for roof cleaning. When mixed with water and applied to the roof surface, the bleach can effectively kill algae, mold, and mildew. However, it is important to use this solution with caution, as it can be harmful to plants and may cause corrosion to metal surfaces.

Additionally, when using chlorine bleach solutions, it is crucial to take proper safety precautions, including wearing protective gear and ensuring proper ventilation in the work area. It is also important to follow manufacturer recommendations for dilution and application to avoid damaging the roof or surrounding areas.

Sodium Hydroxide-Based Cleaners

Cleaners containing sodium hydroxide offer strong alkaline properties that can effectively tackle stubborn stains and contaminants on the roof surface. These cleaners are particularly effective for removing grease, oil, and some types of organic growth. However, sodium hydroxide-based cleaners can be corrosive and should be handled with care to avoid skin and eye irritation.

Hydroxide-based cleaners can be used with caution on various roof materials, including asphalt shingles, metal, and concrete tiles. However, it is important to carefully follow application instructions and thoroughly rinse the roof surface after use to prevent damage or discoloration.

When using sodium hydroxide-based cleaners, be sure to wear protective gear, such as gloves and goggles, and avoid contact with skin and eyes. It is also essential to take measures to protect surrounding vegetation and landscaping from potential harm.

Sodium Percarbonate Solutions

On a completely different note, sodium percarbonate(also known as oxygen bleach) solutions offer an eco-friendly alternative for roof cleaning. This chemical breaks down into oxygen, water, and soda ash, making it safe for the environment and surrounding vegetation. It can effectively remove dirt, grime, and organic stains from the roof surface without causing damage to the roofing material.

One of the key advantages of sodium percarbonate solutions is that they do not produce harmful fumes or odors, making them safe for use in residential areas. They are also gentle on the hands and skin, reducing the need for extensive safety gear during application.

Eco-Friendly and Biodegradable Options


When considering eco-friendly and biodegradable options for roof washing, it is important to weigh the benefits of minimizing environmental impact and reducing potential harm to surrounding vegetation and water sources. These options are often safer for use in residential areas and can be beneficial for homeowners looking to prioritize sustainability.


Some eco-friendly and biodegradable options may require more frequent applications or longer exposure times to achieve the desired cleaning results. Additionally, these solutions may be less effective for tackling tough stains and contaminants compared to traditional chemical cleaners, requiring additional effort and resources for thorough roof cleaning.

Safety and Precautionary Measures

After deciding to wash your roof, it’s essential to prioritize safety. Whether you’re a professional contractor or a homeowner taking on the task, following the necessary precautionary measures is key to a successful and accident-free roof washing process.

Personal Protective Equipment (PPE)

One of the most important aspects of roof washing is the use of personal protective equipment (PPE). This includes but is not limited to, safety goggles, gloves, non-slip footwear, and a respirator. When working with powerful chemicals, it’s imperative to protect yourself from potential exposure and inhalation of harmful fumes. Furthermore, wearing the appropriate PPE ensures that you are shielded from any potential splashes or spills during the cleaning process.

One should never compromise on the quality of PPE, as it can greatly minimize the risk of accidents and injuries during the roof washing process.

Protecting Landscaping and Surrounding Areas

On top of ensuring personal safety, it’s crucial to consider the protection of landscaping and surrounding areas during roof washing. To prevent damage to plants, grass, and other delicate surfaces, it is recommended to thoroughly wet these areas before, during, and after the cleaning process. Additionally, covering them with tarps or plastic sheeting can provide an extra layer of protection against any potential chemical runoff or overspray.

To avoid any unnecessary harm, it is important to take extra precautions and safeguard the surrounding environment from the impact of the roof washing chemicals and equipment.

Ensuring Structural Safety

An often overlooked aspect of roof washing is ensuring the structural safety of the building. Before beginning the process, it is essential to inspect the roof for any signs of damage or deterioration. Additionally, securing loose shingles, checking for any weak spots, and reinforcing the gutters can prevent any unforeseen issues during the cleaning process.

Using appropriate equipment, such as sturdy ladders and harnesses, is also crucial to ensure the safety of anyone undertaking the roof washing task. By making structural safety a priority, you can avoid potential accidents and damage to the building.

Application Techniques for Roof Washing

Now that you have selected the best chemical for washing your roof, it’s essential to understand the various application techniques to ensure a thorough and effective cleaning process. Proper application techniques can make a significant difference in the outcome of your roof washing project, so let’s explore some key considerations.

Manual Scrubbing vs. Low-Pressure Washing

Washing your roof can be achieved through manual scrubbing or low-pressure washing methods. Manual scrubbing involves physically scrubbing the surface of the roof with a brush or sponge, which can be effective for removing stubborn stains and debris. On the other hand, low-pressure washing utilizes a gentle, controlled water flow to wash away dirt and grime without damaging the roof surface. When choosing between the two methods, consider the condition of your roof and the level of cleaning required.

This decision will ultimately depend on the type of roof material and the extent of the cleaning needed. Low-pressure washing is generally recommended for delicate materials such as shingles, while manual scrubbing may be suitable for tougher surfaces.

Tips for Effective Chemical Application

An important aspect of roof washing is the effective application of the cleaning chemical. Proper chemical application ensures that the cleaning solution reaches all areas of the roof and effectively breaks down dirt and contaminants. Here are some tips for effective chemical application:

This systematic approach will optimize the cleaning process and promote a successful outcome. Effective chemical application is crucial in achieving a clean and pristine roof surface while protecting the surrounding environment from potential harm.

When to Seek Professional Help

Roof washing can be a demanding task, especially for larger or more complex roof structures. If you encounter challenging cleaning situations or lack the necessary equipment and expertise, it may be time to seek professional help. Professional roof washing services have the experience, resources, and specialized tools to handle intricate cleaning tasks with precision and efficiency.

Professional assistance can also be beneficial when dealing with stubborn stains, delicate roof materials, or safety concerns. By entrusting the job to skilled professionals, you can ensure a thorough and safe roof cleaning process, ultimately preserving the integrity and longevity of your roof.

Maintenance Tips Post-Washing

Unlike other surfaces, roof maintenance doesn’t end after a thorough washing. It’s important to take proactive measures to ensure that your roof stays clean and free from organic growth in the future. Here are some tips to consider:

Routine Inspections

For routine inspections, make sure to check your roof for any signs of moss, algae, or lichen regrowth. Address any issues promptly to prevent further accumulation. Regular inspections will allow you to catch any problems early and take action before they escalate, potentially saving you time and money in the long run.

Preventive Measures Against Future Growth

Against future growth, it’s essential to take preventive measures to prevent the reoccurrence of moss, algae, or lichen on your roof. This can include trimming overhanging branches, keeping gutters clean, and applying a specialized treatment to inhibit the growth of organic matter.

It’s important to regularly clean your roof to prevent the buildup of debris and organic growth, ensuring its longevity and structural integrity. By following a routine maintenance schedule, you can stay ahead of potential issues and protect your investment in your home.

When to Schedule Your Next Roof Cleaning

Maintenance of your roof is crucial, so it’s essential to have a clear plan for scheduling your next cleaning. Depending on your location and climate, it’s advisable to schedule a professional roof cleaning at least once a year to ensure that any potential issues are addressed promptly.

Measures such as regular inspections and preventive maintenance against future growth will help you determine when it’s time to schedule your next roof cleaning. By staying proactive and attentive to your roof’s condition, you can maintain a clean and well-protected surface for years to come.

To wrap up

Now that we have explored the various options for washing a roof and the different chemicals that can be used, it is clear that the best chemical for washing a roof depends on the type of roof material and the specific cleaning needs. For asphalt shingle roofs, a combination of water, mild detergent, and chlorine bleach can be effective. On the other hand, for metal roofs, a solution of water and a mild detergent is likely your best bet. Whichever chemical you choose, it is crucial to follow safety precautions and manufacturer’s instructions to ensure the best results and longevity of your roof.

When selecting a chemical for washing your roof, it is important to consider the potential environmental impact and impact on surrounding landscaping. Additionally, consulting a professional roof cleaning service can provide valuable insight and ensure that the best and safest chemical is used for your specific roof type and condition. As always, it is essential to prioritize safety and follow best practices for roof cleaning to maintain the integrity of your roof and protect your home.


Q: What is the best chemical for washing a roof?

A: The best chemical for washing a roof is a solution of oxygen bleach(commonly known as sodium percarbonate) and water. Oxygen bleach is effective in removing dirt, algae, and moss without causing harm to the environment or the roof surface.

Q: How does oxygen bleach work in cleaning a roof?

A: Oxygen bleach works by releasing oxygen when mixed with water. This oxygen helps to break down and remove stains, dirt, and organic matter from the roof’s surface, resulting in a thorough and safe cleaning process.

Q: Can I use chlorine bleach to clean my roof?

A: It is not recommended to use chlorine bleach for cleaning a roof. Chlorine bleach can be too harsh and may cause damage to the roof materials and harm surrounding vegetation and the environment.

Q: What safety precautions should I take when washing a roof with chemicals?

A: When washing a roof with chemicals, it is important to wear protective gear such as gloves, goggles, and a mask to prevent contact with the cleaning solution. Additionally, cover nearby plants and shrubs with a tarp to protect them from any potential harm.

Q: Is it necessary to rinse the roof after applying the cleaning solution?

A: Yes, it is essential to thoroughly rinse the roof after applying the cleaning solution to remove any residue and ensure that the chemicals do not linger and potentially cause damage. Use a gentle water stream or low-pressure washing to rinse the roof surface.