Zep Commercial House and Siding Pressure Wash Concentrate is a concentrated formula that makes up to 20 Gal. per container (dilution 6 oz. per gallon of water (1:20)). This product is specially formulated for use in pressure wash machines with downstream injectors (if the machine does not have this capability it may require manual application). It aggressively removes dirt and stains caused by algae, mold, mildew and other sources of soils from vinyl siding, hard coat stucco, brick, wood and aluminum siding.