Using a garden hose or a pressure washer, wet the mildewed area with water.
Using a pump sprayer, apply BEHR PREMIUM® All-In-One Wood Cleaner to the mildewed area.
Reapply the cleaner as needed to keep the surface wet. Allow the solution to remain on the surface for 10-15 minutes. Scrubbing may be required on severely stained surfaces.
Thoroughly rinse the surface with water. Allow it to dry.