Vinyl siding is usually regarded as a low-maintenance choice for siding homes, but that is not entirely true. While vinyl siding almost never requires re-painting, it does need some maintenance. Every year to a year and a half you should thoroughly wash your vinyl siding.
Vinyl siding often collects dirt, mildew and mold. This is especially true in areas of your home where there is little sunlight and where shrubs and trees brush up against the siding.