How do I clean fibre cement siding?
How much and what kind of maintenance / cleaning your James Hardie Fiber Cement siding needs depends on your where you live and what kind of environmental exposure your building gets.
Remember: Always wear appropriate protection (gloves and eye-wear) and shield any landscaping or vegetation while you’re cleaning your siding.
Clean your James Hardie Fibre Cement siding every 6-12 months.
We recommend that you clean your siding every 6-12 months at minimum to remove dirt, dust, chalking, oil, grease, organic contaminants, or mold that may build up on the products surface over time. That said, some areas require maintenance / cleaning more frequently than that.
How to clean James Hardie Fibre Cement siding.
It’s always suggested that you work with one small section at a time, starting from the top and working your way down. This prevents dripping or streaking onto the cleaned areas. Gently clean the siding with a soft brush or wet soft cloth in a side-to-side motion in the direction of the plank siding. If your cleaning panel, the cleaning direction of the siding is up and down.
Do not push the soft brush or wet cloth too hard against the products surface.
Do not allow the soap and mildew cleaner to dry on the siding (continually rinse the area until all of the cleaner has washed off of the siding).
Any areas that have been missed may show up when the siding has dried. Spot clean and rinse those missed areas as needed. If your surface still looks dirty after using the washing methods outlined above, the problem may be mildew.
How to clean mildew off of Fibre Cement siding.
Mildew discoloration is usually found in damp, dark areas or during prolonged humid conditions. Mildew discoloration can resemble dirt. Moisture is the most important single factor in the growth of mildew, which can lie dormant for years. For this reason, we recommend following all of the instructions and precautions that are outlined on the label of the mildew cleaners and wear all protective equipment that is prescribed. At all times, care must be taken not to use harsh or harmful chemicals that can damage the finish on the siding.
Be careful if you’re using a pressure washer to clean your siding.
Warning: High pressure water blasting and sand blasting may damage the surface of the fiber cement product. Use a low pressure water spray and a soft or medium bristle brush (nonmetal). That tends to be the most suitable combo for cleaning fiber cement products. Acid washing can damage the fiber cement surface and is never recommended.
And remember, if you’re using a pressure washer, take care and ensure that the water stream doesn’t damage the surface of the siding. Damage to siding arising from improper cleaning or maintenance may not be covered by the James Hardie warranty. To minimize the chance of damaging the siding, use wide-fan tips that are kept a minimum of 6 feet from the wall and at pressures under 1500 psi.