Things You'll Need
Low-pressure power washer
Bicarbonate of soda
Stucco is a durable cement-based material used to coat indoor and outdoor walls. Despite its durability, it isn't immune from smoke stains and other types of grime. You can remove smoke residue from outdoor stucco with a power washer, but it's essential to use a lower-pressure model because too much force will damage the surface of the stucco. Always wear protective goggles when cleaning stucco or other concrete surfaces.
Wash outdoor stucco with a low-pressure power cleaner using a cleaning solution made up of a dishwashing detergent, 1 cup of borax, 1 cup of washing soda and 2 gallons of hot water.
Position the water nozzle no more than 36 inches from the stucco wall but always maintain a 1-foot distance between the washer nozzle and the wall to protect the stucco's surface.
Move the water sprayer evenly over the surface rather than in concentrated bursts. Start from the bottom and work upward, moving the nozzle from side to side. Rinse the wall thoroughly using a garden hose after pressure washing.
Remove any remaining smoke stains with sugar soap powder -- 3.5 ounces of powder to 1.05 gallons. Alternatively, try bicarbonate of soda mixed with household bleach.
Apply the cleaning solution to the surface of the stucco with a brush and scrub it with a scouring cleanser. Rinse the wall thoroughly after scrubbing it. You can also use this cleaning solution on indoor stucco.
Vacuum indoor stucco to remove surface grime before applying a cleaning solution.
Spray outdoor stucco with a garden hose if you aren’t planning to use a pressure washer. Start from the bottom and move up. Pre-wetting the surface before cleaning with a detergent loosens surface staining soil and stops dirty water from being absorbed into the cement.