Unfortunately, there is nothing you can do about this, external factors will determine if your home needs to be washed every year or two to five years. But there are a few steps you can take to reduce the time frames between Pressure Washing your home. First off, be sure to trim trees and bushes a foot or more off your home. This will allow more airflow thus allowing to dry faster. If water seems to stand you may benefit from installing a French Drain, helping water travel away from your home.
Another tip is to keep your gutters clean. Proper working gutters, help keep water from overflowing next to your foundation, but make sure the down spouts take the water away, at least two to three feet.
When you do get your house washed, make sure you or your service professional uses some sort of soap mix that contains an algicide that kills the algae. Just using water or even hot water just adds to the moisture. Even though your home maybe clean when complete, rest assured mold and algae will be back quickly. Using an algicide in the soap mix allows Innovative Glass to put a one-year warranty on all pressure washing jobs.