Mildew is a fungus feeding and growing on the paint film or caulk and is identifiable by its grey, brown, green or dark black "splotchy" spots.
- Combination of moisture, poor ventilation and lack of direct sunlight. Underside of soffits and eaves are especially prone to mildew.
- Painting over a surface or prior paint film that still had mildew.
- Use of lower quality paint having inadequate mildewcide.
- Not priming bare wood before painting.
- Wearing eye protection (goggles) and rubber gloves, scrub vigorously with a trisodium phosphate cleaning solution or a household bleach solution of 1 part bleach to 3 parts water.
- Let the solution set on the cleaned are for 10-15 minutes.
- Rinse with clean water.
- Wash the area with a detergent solution and rinse again.
- Let completely dry and paint with a high quality latex house paint.