I usually recommend pressure washing your house at least once a year. Sometimes twice if you live in a shaded area or have a side of your house that grows mildew easily. We offer a Soft Wash which is a low pressure cleaning. We let the cleaning solution break down the mildew,dirt, and grime. If your driveway or patio has black or green mildew we spray the cleaning solution on it then use a surface cleaner. It uses high pressure and a spinning head which cleans evenly with no streaks. I hope this answers your question. Check out my video below to see the surface cleaner in action.