Is it Safe to Pressure Wash Hardie Siding?
Updated: Jul 1, 2022
When it comes to cleaning siding, many homeowners consider pressure washing to be the best option. This is because it can remove years of built-up dirt and grime, making the home look new again.
However, some people are hesitant to use this method because they are not sure if it is safe. In particular, they are concerned about the possibility of damaging their Hardie board siding.

Hardie siding is a composite material that is made up of two layers. The first layer is a waterproof membrane and the second layer is a fiberglass mat that protects the first layer.
The product has been designed to resist corrosion, moisture, and mold.
Although pressure washing is a common and often effective way to clean surfaces, there are some risks associated with the process. One of these is the potential for damage to your home's Hardie siding.
Before you pressure wash your home's Hardie siding, it's important to consider the risks involved and make sure that you're taking appropriate precautions.
First, always read the manufacturer’s instructions for your particular type of Hardie siding.
Second, use a mild soap or low-pressure water when cleaning your siding. And finally, wait at least two hours after washing before taking any of the steps to protect the finish, such as applying a sealant or wax.
Third, use a detergent specifically designed for Hardie siding that contains biocides and corrosion inhibitors.
Pressure washing is a common way to clean exterior surfaces but not always the recommended.
However, many homeowners don't realize that pressure washing the hardest of surfaces, such as Hardie siding, can be dangerous and hard spray from a pressure washer can damage the surface. There are several reasons why this type of cleaning can be risky.
Hardie siding is made with a synthetic material that may not stand up to the high pressures used in a pressure washer and water can easily be pushed up under the siding causing additional problems down the road.
Additionally, the chemicals used in most pressure washers can damage the surface finish on Hardie siding.
Tips For Cleaning Your Fiber Cement Siding
First, make sure to use a soft-bristled brush when cleaning it to avoid any scratches. You can always use a wet rag but make sure to rinse frequently to prevent the dirt from reattaching to the surface.
Secondly, using a mild detergent in the process will help move the dirt from the siding making it easier to remove.
Finally, be sure to seal it once a year with a sealant or wax to protect it from the weather.
Fiber Cement Siding Maintenance Recommendation Direct from Manufacturer: https://www.jameshardie.com/product-support/resource-center/fiber-cement-siding-maintenance
In conclusion, one of the best and safest ways to clean Hardie siding is through Softwashing.
Softwashing is the process of cleaning a surface with a low-pressure, high-volume water stream. This gentle cleaning method is perfect for delicate surfaces like brick, stone, wood, and synthetic siding such as Hardie siding.
Softwashing can be used to remove built-up dirt, grime, algae, and moss from a surface. It is also an effective way to prepare a surface for painting or staining.
In most cases, Hardie siding will require a soft brush or cloth with low-pressure water to remove built-on dirt. It is recommended that you should consult with a professional Softwash company to ensure proper cleaning of all exterior surfaces of your home.
Learn more about our Softwash process today!