Can you power wash James Hardie siding?

Can you power wash James Hardie siding?

James Hardie, the manufacturer, generally advises against high-pressure washing its fiber cement siding, warning that pressure above roughly 1,500 PSI can strip the surface finish, expose raw cement, and potentially void your warranty. Their official recommendation is a garden hose on low pressure combined with a soft, non-metal bristle brush, working top to bottom in the direction of the panels. For grease or stubborn grime, a bucket of water mixed with mild dish soap is generally sufficient. If you do choose to pressure wash, most experts recommend staying well under 1,500 PSI, using a wide fan-angle nozzle, and keeping the nozzle at least six feet from the surface at all times. Harsh chemicals, bleach, and metal brushes should be avoided entirely, since they can etch the surface. When in doubt, a professional soft-washing service is the safest route for Hardie board.