Mildew resembles dirt in appearance. Can look gray, brown or black. Often found in areas that receive little direct sunlight; eaves and areas of northern exposure. Mildew is a fungus and does not need light.
Mold and algae grow in the same areas that mildew does but usually requires more frequent moisture. Often found around leaky faucets. Mold and algae are plants and require light.
Painting over an area without removing growth or using a low quality paint without a mildewcide/algaecide.
Poor home maintenance. Not washing the home or keeping plants trimmed back from the home.
If you apply some diluted bleach to suspected areas and they disappear, it’s mildew.
Prior to painting you should power wash and apply a diluted solution of bleach and water. 1 cup bleach to a gallon of water up to 1 part bleach to 3 parts water if needed for real problem areas. It is best to wet the area and then apply the solution. Let it set for 10 minutes and rinse.
To maintain a home you should wash it twice a year. Spring and Fall are good choices. I do not recommend using a bleach solution for maintenance but suggest some of the mild house wash solutions that use activated oxygen to kill mildew, algae and mold. Sashco CPR or Krud Kutter House Wash are good choices.
If you found this article helpful, be sure to check in regularly with The Painting Company for more helpful tips and advice!