Mildew/mold spores are present in the air, so it is difficult to keep a house free of mildew/mold growth if it is damp. Reduce the potential for damp conditions by trimming shrubbery, plants, and trees to permit more airflow and exposure to sunlight. Scrub the affected surface with a brush using the following solution: 1 qt. liquid chlorine bleach, 2/3 cup trisodium phosphate (available in hardware or paint stores), 1/3 cup laundry detergent, and 4 qt. warm water. A solution of vinegar (30%) and water (70%) has also proven successful. Work a small area at a time and rinse well before it dries. After the surface dries, it may be treated with a commercial fungicide to prevent further growth. Make sure ammonia is not mixed with chlorine bleach since harmful fumes will result. Avoid contact with eyes and skin. Wear rubber gloves and safety goggles. Cover shrubs and grass with a plastic sheet to avoid damage to plants and grass. The solution may damage metal rain gutters, so control runoff and rinse surfaces contacted by the solution.