The Best Way to Eliminate Mildew on a Ceiling

Causes of Mildew

• The primary cause of mildew and mold is excessive moisture. Any consistently warm, moist area is prone to regular mildew and mold growth. Proper ventilation will help prevent recurrences, but water leaks, poor ventilation, inadequate insulation and excessive wetness will make it difficult, if not impossible to eradicate mildew and mold growth permanently. The longer the moisture remains in a confined area, the faster the mildew and mold growth will spread. Maintaining a dry environment will prevent recurring infestations.

Testing for Mildew

• Mildew is easily distinguished from dirt by examining it under a high-powered magnifying glass. The fungus causing mildew is characterized by a thread-like growth. To test for the presence of mildew on paint, apply one or two drops of household bleach to the stain. Mildew stains will bleach out within a few minutes, but stains that don't bleach out are probably dirt. The use of fresh bleach is essential for ensuring potency.

Removing Mildew

• According to the Environmental Protection Agency and the Federal Emergency Management Agency, mildew must be removed from a contaminated ceiling prior to painting. Although paint may temporarily conceal the visible signs of mildew, unless the problem that caused it in the first place is eradicated, persistent mildew will eventually becomes mold and result in a serious environmental health hazard. A professional examination will determine the source of the problem and provide information about effective long-term remediation.

Additives for Paint

• When painting a ceiling that was contaminated with mildew, avoid using primers containing linseed oil. Linseed oil, particularly when used in warm, humid climates, attracts the fungus that causes mildew and subsequent mold growth. Look for primers designed to work with acrylic latex paint. If using an all-in-one product, consult with the paint store to determine if a mildewcide can be added to the product to inhibit any potential growth. Always use an acrylic latex paint as it is more effective at inhibiting mildew growth. Paint stores may be willing to add a paint-specific fungicide to an acrylic latex paint that doesn't already contain it.