Wash the siding with a pressure washer set to the lowest setting. If you find you aren’t getting very good results, gradually increase the pressure, but always test on an inconspicuous area of the siding as you add more pressure to ensure there isn’t any damage.
Mix a solution of 1/8 cup laundry detergent for every 2 gallons of water. Agitate the water till the detergent has completely dissolved.
Dip a large scrub brush into the soapy mix and use this to scrub any remaining dirt from the siding. Use a sturdy ladder to reach high areas of the home and begin washing at the top, gradually working your way down.
Rinse the siding with a hose to remove any soap residue.
Scrub away corrosion with sand paper. Corrosion can be identified as any dark spots on the aluminum siding.
Mix 3 cups of bleach into a gallon of water to make a cleaning solution for mold or mildew stains on the siding. Scrub with this solution on any areas with a green stain that remains after the prior steps.