Mildew is a fungus that feeds and grows on the paint film or caulk and is identifiable by its grey, brown, green, or dark black splotchy spots.
o Moisture, poor ventilation and lack of direct sunlight have combined to create an environment where fungus can thrive. The underside of soffits and eaves are especially prone to mildew.
o Paint was applied over a surface or prior paint film that still had mildew.
o A lower-quality paint was used, without adequate mildewcide.
o Bare wood was not primed before painting.
Repair and Prevention
o 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.
o Let the solution set on the cleaned are for 10 to 15 minutes.
o Rinse with clean water.
o Wash the area with a detergent solution and rinse again.
o Let completely dry and paint with a high-quality latex house paint.