Cleaning and Maintaining James Hardie Siding

Cleaning and maintaining the exterior of your home is an important part of sustaining its beauty and value. Proper care of your James Hardie siding will not only ensure that its beauty will last for years, but that your warranty will last for years. Like most warranties, damage to siding arising from improper cleaning or maintenance may not be covered by the James Hardie warranty.

As a fiber cement siding, James Hardie siding has specific and unique care and maintenance qualities. Our goal is to make sure you have the tools and resources to keep your James Hardie siding looking and performing like new. Specific care and maintenance of your siding will depend on your geographic location, the exposure of the building, and whether your product is a prime or ColorPlus product. In general, cleaning is recommended to remove dirt, dust, chalking, oil, grease, organic contaminants, or mold that may build up on the product surface over time. It’s also important to note that upon installation, the dust from cutting and construction must be removed immediately (refer to the cleaning instructions in the technical bulletin below). For more information on cleaning and maintaining your James Hardie siding, see Technical Bulletin #20 “Cleaning and Maintenance” at

As a guide, it is recommended that care and maintenance of both HZ5 and HZ10 HardieZone® Systems include, but are not limited to, the following normal care and maintenance tasks:


  • Wash down the exterior surfaces of your siding every 6 to 12 months with a garden hose or low pressure water spray to remove dirt and debris.
  • James Hardie Products with ColorPlus® Technology can be cleaned using water and a soft brush or rag. For stubborn dirt or stains, a mild detergent and a soft brush may be used.
  • For paint applied in the field, refer to your paint manufacturer for washing and   maintenance requirements related to paint performance.

Pressure Washer and Acid Washing Warnings

  • High pressure water blasts and sand blasting may damage the surface of James Hardie fiber cement products.
  • Low pressure water spray and a soft medium bristle (nonmetal) brush is most suitable for cleaning fiber cement products.
  • Acid washing can damage the fiber cement surface and is not recommended.
  • Note: If using a pressure washer, care must be taken to ensure that the water stream does not damage the surface of the siding. Using wide fan tips that are kept a minimum of 6 feet from the wall and at pressures under 1500 psi will minimize the chance of damaging the siding.


  • It’s important to reapply caulking when it begins to show signs of wear, as this can help keep moisture from getting into the wall cavity.
  • Caulking areas include, but are not limited to: penetrations, flashings, plank and trim connections, and in some cases, between plank joints.
  • James Hardie recommends the use of caulks and sealants that remain permanently flexible. Look for the words “permanently flexible” written clearly on the label or in the accompanying literature.
  • For best results use an Elastomeric Joint Sealant complying with ASTM C920 Grade NS, Class 25 or higher, or a Latex Joint Sealant complying with ASTM C834. Caulking/sealant must be applied in accordance with the caulking/sealant manufacturer’s written instructions or ASTM C1193.

Keep Your Gutters Clean

  • Clean out your gutters, blocked pipes, and overflows as required.

Landscaping, Ground Clearance, and Drainage Slopes

  • It is a good practice to keep vegetation such as shrubs, bushes, and small trees trimmed back and away from the home and siding. This will also help to ensure that sprinkler systems do not saturate areas near the building.
  • Ensure required external ground clearances (typically 6”) and drainage slopes are maintained.
  • Do not fill landscaping up to the siding.


  • James Hardie ColorPlus® products can refresh their look by washing down dirt and debris from the siding.
  • Note: Repainting over the top of James Hardie ColorPlus® before the 15 year limited ColorPlus warranty is expired, will void the finish warranty. However if repainting is desired, refer to our Technical Bulletin S-100 located on our website for painting tips.
  • ColorPlus® Touch Up is used to cover nicks, scrapes and nail holes that may occur during installation. ColorPlus® touch up comes in bottles tailored to be edge coaters or touch up pens. If the touch up area is larger than the size of a dime, the use of touch up is NOT recommended. Installers are advised to replace the damage siding with a new section of ColorPlus plank or panel.
  • PrimePlus Products
  • If your James Hardie siding was originally painted after it was installed on your home, then check the original paint manufacturer recommendations for reapplication of paint.
  • Do not use stain on James Hardie Products.

 Repair or Patching

  • Dents, chips, cracks and other minor surface damage in James Hardie siding and trim products can be filled with cementitious patching compound.
  • Refer to manufacturer recommendations for products that are compatible with fiber cement.

Use of Deicing Salts

  • James Hardie siding products should not come in direct contact with deicing salts. The salts may prematurely damage the finished look of the siding.
  • James Hardie recommends the use of sand or gravel to manage snow loads near siding.