I am an industrial coatings salesman with 42 years experience in selling to OEM-type accounts, but I am also on the architectural review board of an 80-unit, high-end townhouse development. I can't find a solution to a problem concerning extreme mildew on our painted, cedar-sided townhouses. They are approximately 11 years old, well-insulated, and are painted every four years with top-quality stain.
The painting contractor claims that the solid-color stain contains a sufficient amount of mildewcide in the formula, and the surfaces are pressure-washed prior to each painting cycle. However, after about two years, the mildew returns with a vengeance and seems to be worse as time goes on.