All exterior surfaces collect dirt, dust, and contaminants and require cleaning. It is necessary to clean them periodically to keep them looking good. Green Plank® composites are low-maintenance products, not no-maintenance products. Periodic cleaning of Green Plank® composite products is suggested, even if they appear clean, it is important to prevent the build-up of pollen/debris that can cause mold. We recommend a basic cleaning with a composite deck cleaner or combination of soap (dishwashing detergent), hot water, and a soft-bristle brush. After cleaning rinse thoroughly. If unsure about the product being used to clean/ remove stains from your deck, it is recommended that you test a small area in an inconspicuous place to determine if the product will cause any unwanted discoloration. Hose off the entire deck with a garden hose and not with a pressure washer. The pressure washer will spray particles of soap on other surfaces, possibly causing staining. Using a garden hose is a better practice to gently rinse off the homemade cleaner and get rid of all water spots. Household pressure washers with spray nozzle may be used to remove stains, ground in dirt, or mold but risks spraying particles of soap on other surfaces.