Flagstone is a popular choice for outdoor patios, walkways, and other landscaping projects. It is a type of flat, natural stone that typically has a rustic and unique appearance. Over time, however, flagstone can become dirty and worn-looking due to exposure to the elements and foot traffic.

Pressure washing is a common method used to clean various outdoor surfaces, but can it be used on flagstone? The answer is, it depends. While pressure washing can be effective in removing dirt, grime, and even some stains from flagstone, it needs to be done correctly to avoid damaging the stone.

One important factor to consider is the type of flagstone you have. Some types of flagstone are more durable and can withstand the force of a pressure washer, while others are more delicate and can easily be pitted or cracked under pressure. If you are unsure about the type of flagstone you have, it is best to err on the side of caution and avoid using a pressure washer.

Is Pressure Washing Safe for Flagstone?

Flagstone is a popular choice for outdoor surfaces due to its natural beauty and durability. However, over time, flagstone surfaces can accumulate dirt, grime, and moss, which can dull its appearance and make it slippery. Many homeowners wonder if pressure washing is a safe and effective method to clean flagstone.

The answer depends on several factors, including the type of flagstone, the condition of the surface, and the pressure washing technique used. While pressure washing can effectively remove dirt and grime from flagstone, it can also cause damage if not done correctly.

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Type of Flagstone

Not all flagstone is created equal, and some varieties are more prone to damage from pressure washing. Soft or porous flagstone, such as sandstone or limestone, can be easily eroded by high-pressure water. In contrast, harder types of flagstone, such as granite or slate, are more resistant to damage.

Surface Condition

The condition of the flagstone surface is also an important factor to consider. If the flagstone is already cracked or damaged, pressure washing can exacerbate these issues, causing further deterioration. It is recommended to inspect the flagstone for any existing damage before attempting to pressure wash.

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Moss and algae growth is another common issue on flagstone surfaces. While pressure washing can effectively remove this growth, it is important to use a low-pressure setting and avoid using harsh chemicals that can harm the flagstone or surrounding vegetation.

Pressure Washing Technique

The key to safely pressure washing flagstone is to use the right technique. It is crucial to adjust the pressure washer’s settings to a low-pressure setting and use a wide fan nozzle to disperse the water evenly. This will minimize the risk of damaging the flagstone surface.

Additionally, it is recommended to start with a test area in a less visible area to determine the appropriate pressure and technique before cleaning the entire flagstone surface. This will help ensure that the pressure washing process is safe and effective.

In conclusion, pressure washing can be a safe and effective method to clean flagstone, but it is crucial to consider factors such as the type of flagstone, surface condition, and pressure washing technique. By taking these precautions, homeowners can enjoy a clean and vibrant flagstone surface without causing any damage.

The Pros and Cons of Pressure Washing Flagstone

Pressure washing flagstone can be an effective way to clean and restore the natural beauty of the stone. However, it is important to consider the pros and cons before using this method, as it may not be suitable for all situations.


  • Efficiency: Pressure washing can quickly and efficiently clean flagstone, removing dirt, stains, and moss with ease. It can save a lot of time and effort compared to manual scrubbing or chemical treatments.
  • Restoration: Pressure washing can rejuvenate weathered or faded flagstone surfaces, bringing out their natural colors and patterns. It can make old flagstone look like new again.
  • Environmentally friendly: Pressure washing typically does not require the use of harsh chemicals, making it a more eco-friendly option for cleaning flagstone. It uses the power of water to clean the stone without causing harm to the surrounding environment.
  • Preventive maintenance: Regular pressure washing can help prevent the buildup of dirt, grime, and moss on flagstone, prolonging its lifespan and reducing the need for costly repairs or replacements.
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  • Potential damage: Pressure washing can be too powerful for delicate or thin flagstone, causing it to crack or chip. It is important to use the appropriate pressure setting and technique to avoid damaging the stone.
  • Loss of natural patina: If you prefer the aged or weathered look of your flagstone, pressure washing may remove some of the natural patina. Consider the desired aesthetic before deciding to pressure wash.
  • Maintenance requirements: Pressure washing is not a permanent solution and may need to be performed regularly to keep flagstone looking its best. This can add to the overall maintenance requirements of the stone.
  • Professional expertise: For larger or more complex flagstone areas, it may be best to hire a professional with experience in pressure washing. They can ensure the job is done correctly and without causing damage to the stone or surrounding areas.

Before pressure washing flagstone, consider these pros and cons to make an informed decision about the best approach for cleaning and maintaining your flagstone surfaces.

Alternative Cleaning Methods for Flagstone

Pressure washing is a common method for cleaning flagstone, but it’s not the only option. If you’re concerned about the potentially abrasive effects of pressure washing or want to explore alternative cleaning methods for your flagstone, there are several alternatives to consider.

1. Scrubbing with a Bristle Brush

One alternative to pressure washing is to scrub the flagstone surface with a bristle brush and a mixture of mild detergent and water. This method allows you to be more gentle with the stones while still effectively removing dirt and stains. Make sure to use a brush with soft bristles to avoid scratching the surface of the flagstone.

2. Chemical Cleaners

Another option is to use chemical cleaners specifically designed for flagstone. These cleaners are typically formulated to break down and remove dirt, algae, mold, and other stains without damaging the stone. Be sure to follow the manufacturer’s instructions and test the cleaner on a small, inconspicuous area before applying it to the entire surface.

Note: When using chemical cleaners, always wear protective gloves and eye goggles to prevent any potential harm or irritation.

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If you choose to use chemical cleaners, it’s important to thoroughly rinse the flagstone after cleaning to avoid any residue.

In addition to these alternative cleaning methods, regular maintenance and prevention can also help keep your flagstone looking its best. Sweeping or blowing away debris, keeping the area well-ventilated to discourage the growth of algae or mold, and promptly cleaning up spills can all help preserve the appearance and longevity of your flagstone.

Remember, it’s essential to assess the condition of your flagstone and consider the manufacturer’s recommendations before choosing a cleaning method. If you’re unsure, consulting with a professional can help ensure you choose the right approach for your specific situation.

Questions and answers

Can you pressure wash flagstone?

Yes, you can pressure wash flagstone. Pressure washing can be an effective way to clean flagstone surfaces.

Is pressure washing safe for flagstone?

Pressure washing can be safe for flagstone if done correctly. It is important to use the right PSI setting and a wide spray pattern to avoid damaging the stone.

What PSI should be used for pressure washing flagstone?

The recommended PSI for pressure washing flagstone is around 1500 to 2000. Using a higher PSI can cause damage to the stone.

Can pressure washing remove stains from flagstone?

Yes, pressure washing can help remove stains from flagstone. However, some stubborn stains may require additional cleaning methods or products.

Are there any precautions to take when pressure washing flagstone?

Yes, there are precautions to take when pressure washing flagstone. It is important to avoid using high pressure or narrow spray patterns, as they can cause damage. It is also advisable to test a small, inconspicuous area before proceeding with pressure washing the entire surface.

Can I use a pressure washer to clean my flagstone patio?

Yes, you can use a pressure washer to clean your flagstone patio. However, you need to be careful not to use too high of pressure or too narrow of a spray nozzle, as it can damage the stone. It is recommended to use a wide spray nozzle and keep the pressure relatively low to avoid any potential damage.