What Is the Difference Between Mold and Mildew?

Mildew is a surface fungus that commonly appears on damp organic materials like paper, leather, or fabrics. It starts as white or gray spots that later turn yellow, brown, or black. It has a powdery or fluffy texture and tends to grow in a flat, spreading pattern. Mildew is generally easier to clean because it only grows on the surface of materials.

You often find mildew in high-moisture areas like shower walls, window sills, or on stored books. It thrives where ventilation is poor. While it can damage the items it grows on, it does not typically compromise the structural integrity of your home. Cleaning it with household cleaners is often sufficient for small, surface-level growth.

Exposure to mildew can sometimes cause minor allergic reactions, such as coughing or a headache, especially in sensitive individuals. However, its health effects are generally considered less severe than those from mold. Mildew is primarily a surface nuisance that you can address with proper cleaning and by reducing moisture.

Mold exposure poses greater health risks for many people. Inhaling mold spores can trigger allergic reactions, asthma attacks, and respiratory issues. Some individuals may experience more significant symptoms like sinus congestion or skin irritation. If you or a family member feels unwell and suspects mold, it is wise to see a doctor.

• Allergic reactions like sneezing and itchy eyes.
• Aggravation of asthma and other respiratory conditions.
• Potential for sinus infections and congestion.
• Skin rashes or irritation in some cases.
• Headaches and fatigue from prolonged exposure.
• Severity depends on the mold type and individual sensitivity.

For a small patch of mildew on a non-porous surface, you can likely clean it yourself with a mildew-killing product. Ensure the area is well-ventilated during cleaning. If the mildew returns quickly, it signals an unresolved moisture issue that needs to be fixed to prevent it from becoming a recurring problem.

For mold, especially if the area is larger than about ten square feet, or if it's in your HVAC system, professional assessment is recommended. A qualified mold professional can safely test for and remediate mold. Water damage pros address the source moisture to prevent regrowth, which may involve services like leak detection or structural drying.

• The affected area is larger than a standard trash can lid.
• You smell a persistent, musty odor but cannot find the source.
• Mold is growing in your heating or air conditioning ducts.
• There is visible mold on structural materials like drywall or subflooring.
• Water damage is extensive or has been present for over two days.
• Household members are experiencing worsening allergy symptoms.