Misc. Items - Decks, Steps etc. Mold & mildew are a major problem to the exterior of your house, but it also affects the accessories of your home such as deck, walkways, patios, gazebos, foundations, ramps, sidewalks & sheds etc. These items are also exposed to rain and sun and over time the mold and mildew will build up, making a harsh appearance. The following pictures are of before and after.