Most Long Island homes benefit from a professional House Washing at least once a year. If you notice green or black streaking along your siding, a dull or discolored exterior, or visible mold and mildew growth near the foundation or roofline, it's time to call Power Washing Pro. Seasonal pollen, salt air from the coast, and the humidity of Suffolk and Nassau County summers all accelerate the buildup of contaminants that regular rain simply cannot rinse away.