Cleaning flagstone with a pressure washer can be an effective way to revive the appearance of your outdoor living space, but it requires careful consideration to avoid damaging the delicate stone. This comprehensive guide will provide you with the technical specifications, recommended pressure settings, and step-by-step instructions to clean your flagstone patio or walkway safely and effectively.
Recommended Pressure Setting
When it comes to pressure washing flagstone, the key is to use the lowest possible pressure setting. Flagstone is a relatively soft and porous material, and excessive pressure can cause chipping, cracking, and erosion of the stone surface.
- Pressure Washer Settings: Use a pressure washer with a low-pressure setting, around 2,800 psi, and a wide surface cleaner to clean large areas effectively.
- Start Low: Begin with the lowest pressure setting and gradually increase the pressure if necessary, but be cautious as even a slight increase in pressure can cause significant damage to the flagstone.
- Avoid High Pressure: Flagstone will chip and crack if you use too much pressure, so it’s essential to avoid high-pressure settings, which can range from 3,000 to 4,000 psi or higher.
Avoiding Damage
To prevent damage to your flagstone during the cleaning process, follow these guidelines:
Nozzle Distance
- Keep Nozzle Distance: Maintain a safe distance of at least 12 inches between the pressure washer nozzle and the flagstone surface. This will help to avoid chipping, cracking, and erosion of the stone.
- Adjust Angle: Hold the nozzle at a 45-degree angle to the flagstone surface to distribute the water flow evenly and reduce the risk of concentrated high-pressure streams.
Water Flow
- Avoid Forceful Streams: Don’t use a water stream that is too forceful, as flagstone will erode with prolonged exposure to running water. Opt for a wider, fan-shaped spray pattern to distribute the water more gently.
- Limit Exposure Time: Minimize the amount of time the flagstone is exposed to the pressure washer’s water flow. Quickly move the wand back and forth across the surface to avoid excessive erosion.
Cleaning Solutions
- Avoid Acidic Cleaners: Steer clear of acidic cleaners, as they can lead to stains if left on the surface too long and are dangerous to humans, animals, and plants.
- Use Mild Detergents: Choose a mild, pH-neutral detergent or cleaning solution specifically formulated for use on natural stone surfaces.
- Pretreat Heavily: Apply a heavy pretreat to the flagstone and let it sit for several minutes before rinsing with a low-pressure setting to ensure effective cleaning.
Cleaning Solutions
When it comes to cleaning solutions for flagstone, there are a few options to consider:
Vinegar
- Vinegar: Vinegar is a highly effective and eco-friendly cleaning solution for removing mildew, moss, and stains from flagstone.
- Vinegar Concentration: Mix a solution of 1 part white vinegar to 3 parts water for optimal cleaning results.
- Application: Apply the vinegar solution to the flagstone using a pump sprayer or a soft-bristle scrub brush, let it sit for 5-10 minutes, and then rinse with a low-pressure water flow.
Commercial Cleaners
- Stone-Specific Cleaners: Look for commercial cleaners specifically formulated for natural stone surfaces, such as flagstone. These cleaners are designed to be gentle yet effective at removing dirt, grime, and stains.
- Cleaning Solution Mix: When using a commercial cleaner, follow the manufacturer’s instructions for the recommended dilution ratio, typically around 3-4% cleaning solution to water.
Additional Tips
To ensure the best results and minimize the risk of damage, consider the following additional tips:
Test Area
- Start in a Seldom Trafficked Area: Begin cleaning in a less trafficked part of the patio or walkway to test the pressure washer settings and cleaning solution before tackling the entire surface.
Scrub Brush
- Use a Scrub Brush: Scrubbing the flagstone with a stiff-bristle scrub brush and a mild detergent solution can be an effective alternative to pressure washing, especially for heavily soiled or stained areas.
Joint Refilling
- Refill Joints: After cleaning, refill the joints between the flagstone with stone dust or a similar material, sweep it in, hose it off, and let it dry to help stabilize the stones and prevent weed growth.
Technical Specifications
For optimal results when pressure washing flagstone, consider the following technical specifications:
- Pressure Washer Settings: Use a pressure washer with a low-pressure setting, around 2,800 psi, and a wide surface cleaner to clean large areas effectively.
- Cleaning Solution Mix: Use a 3-4% mix of cleaning solution for optimal results.
- Nozzle Angle: Hold the pressure washer nozzle at a 45-degree angle to the flagstone surface.
- Nozzle Distance: Maintain a distance of at least 12 inches between the nozzle and the flagstone.
- Water Flow: Opt for a wide, fan-shaped spray pattern to distribute the water flow gently across the surface.
Reference:
- Houzz – Best way to clean flagstone patio
- Devine Escapes – How to clean dry laid flagstone | how-to install stone dust in the joints
- YouTube – Flagstone Patio Pressure Washing Revival
- Pressure Washing Resource – Cleaning Flagstone – Stains/Surfaces
- The Grounds Guys – Can You Pressure Wash Flagstone? Yes, If You Do It Right