Mildew is a common problem for homeowners, often appearing as a discoloured patch on exterior walls. While it may be tempting to simply paint over it, this is not a long-term solution. To effectively deal with mildew, it is necessary to remove it and address the underlying cause, which is usually excess moisture. Once the mildew has been eradicated, the affected area should be cleaned and dried before applying a moisture-resistant primer and paint. This comprehensive approach will ensure that the mildew does not return and that your exterior walls remain looking their best.CharacteristicsValuesMildew AppearanceBlack, gray, or brown discoloration on a painted surfaceMildew HabitatDamp environments with little exposure to sunlightMildew TestingApply household chlorine bleach to an affected area; if mildew, it will lighten or disappearMildew RemovalWash with a mixture of household bleach and water (3:1) or a household cleanser designed to kill mildew; scrub with a soft brush; rinse with c...