Can You Pressure Wash Your Roof? Risks and Alternatives

Wondering if you can pressure wash your roof? While pressure washing is great for many outdoor surfaces, it’s not the best choice for your roof. Roofs are delicate, and high-pressure water can cause damage, leading to leaks and other problems. In this article, we’ll explore why pressure washing your roof isn’t recommended and offer safer alternatives for keeping your roof clean and intact.

Can You Pressure Wash A Roof?

Yes, you can pressure wash your roof. However, it’s not recommended. Roofs are delicate surfaces, and the high-pressure water from a pressure washer can easily damage shingles or tiles. This damage can lead to potential leaks and water infiltration, causing costly repairs.

A safer alternative is soft washing, also known as “roof washing,” which uses a lower-pressure output. This method effectively cleans your roof without risking damage. In the next sections, we’ll discuss why soft washing is the better option for roof cleaning and highlight its benefits over pressure washing.

Why You Should Not Pressure Wash a Roof

Pressure washing a roof can cause damage to shingles and the fabric underlayment. It may also result in dirt falling onto other roof sections, causing further problems. Let’s outline the reasons why pressure washing is not recommended for roofs.

It can damage shingles

Using a pressure washer on your roof might seem like a good idea to eliminate dirt and mold. But this method can hurt your asphalt shingles. Fixing or replacing broken shingles costs a lot of money and time.

The high-pressure water strips away the granules that protect the shingles from sun and rain. Once these granules are gone, your shingles get weak and could break. High water pressure can also cause cracks or make small holes bigger in your shingles. When shingles are damaged, water can leak into your house. This leads to more problems inside.

It can damage your roof’s fabric underlayment

Beyond harming shingles, pressure washing can also hurt the fabric layer underneath your roof. This layer acts like a safety net. It catches water that gets past the shingles. But high-pressure water from a pressure washer can tear this fabric. When it rips, water leaks into your house, leading to mold and damage.

Most pressure washers are not made for roof work

Pressure washers are typically designed for cleaning surfaces like driveways, sidewalks, and decks, not roofs. Attempting to use them on roofs can lead to damage and increased risks due to the high pressure they exert.

Pressure washing equipment isn’t tailored to the delicate nature of roofing materials, which can result in unintended consequences such as cracked or broken shingles, water leaks, or other structural issues. Using equipment that is specifically prepared for cleaning roofs will help you prevent potential damage and ensure the safety and integrity of your home’s roofing system

Soft Washing: The Best Way To Clean a Roof

Soft washing is often considered the best way to clean roofs because it’s gentle and achieves effective results. This helps avoid damaging delicate roof materials like shingles or tiles.

You can use a pressure washer to do soft washing, but add special nozzles to reduce the pressure from really strong to just right for roofs. They ensure the pressure stays low, between 150 and 300 pounds per square inch (PSI), so the cleaning is safe.

Besides using low-pressure water, soft washing also includes cleaning solutions to remove dirt, algae, and other stuff from the roof. These solutions can be adjusted based on what’s on your roof and what needs cleaning:

  • Bleach: This is a fast and effective cleaning solution commonly used in soft washing. However, it may cause damage if not properly diluted (three parts bleach to one part water). Ensure thorough rinsing to prevent any residual bleach from causing harm to the roof.
  • Sodium hydroxide: Also known as caustic soda or lye, it effectively kills algae and removes soil from the roof surface. It is preferred for walkable roofs because they require a lower pressure, typically below 500 PSI.
  • Calcium chloride: It provides similar effectiveness to bleach but may leave a white haze on the roof surface. Additional cleaning steps may be required to achieve a clear finish. It’s often chosen for its cleaning power and ease of transportation.
  • Percarbonate cleaners and hydrogen peroxide: They offer effective cleaning without the strong chemical properties of bleach or caustic substances. However, they may require more time to work and may need to be left on the surface for an extended period before rinsing to achieve optimal results.

How to Soft Wash a Roof

To safely and effectively clean your roof, follow these steps:

  1. Inspect the roof for damage and remove debris with a leaf blower.
  2. Wet the roof using a garden spray nozzle to prevent the cleaning solution from drying too quickly.
  3. Mix nontoxic chemicals and water in a garden sprayer to create a soft wash solution that will effectively remove mold growth and dirt without damaging the roof.
  4. Apply the soft wash solution to the roof, ensuring complete coverage, and allow it to sit for 15-20 minutes to penetrate dirt and mold.
  5. Rinse off the solution using a gentle setting on a garden hose to prevent shingle damage and ensure thorough cleaning.

Can I Soft Wash My Own Roof?

Roof cleaning is a complex task, requiring specialized equipment and knowledge to ensure it’s done safely and effectively. If you’re uncomfortable with the idea of cleaning your roof yourself, don’t hesitate to contact professional services.

Professionals have the expertise to identify and address any potential issues with your roof, such as damaged shingles or underlying structural problems. They also have access to specialized tools and cleaning solutions tailored to the specific needs of your roof.


While pressure washing might seem convenient for cleaning your roof, it’s best to avoid it to prevent potential damage. Instead, consider soft washing with gentle chemicals and water or enlist the help of professional services. Roof cleaning requires specialized equipment and knowledge, and professionals can ensure the job is done safely and effectively, saving you time and worry.

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