Mold vs. Mildew: How to Tell the Difference and When to Call a Professional

Not All Fungus Is Created Equal

You've spotted something growing in your bathroom, basement, or around a window—but is it mold or mildew? While these terms are often used interchangeably, they're actually different types of fungi with different implications for your home and health.

Understanding the difference between mold and mildew helps you respond appropriately—whether that means a simple DIY cleanup or calling a professional mold remediation company.

What Is Mildew?

Mildew is a surface-level fungus that typically grows in warm, humid environments. It's commonly found in bathrooms, kitchens, and other moisture-prone areas.

Identifying Characteristics of Mildew

• Appearance: Flat, powdery, or fluffy texture
• Color: Usually white, gray, or light yellow; may turn brown over time
• Location: Grows on surfaces like tile, grout, shower curtains, windowsills, and fabrics
• Smell: Mild musty odor

Health Effects of Mildew

Mildew exposure can cause:

• Coughing and sneezing
• Headaches
• Mild respiratory irritation

While unpleasant, mildew is generally considered less hazardous than mold and is easier to clean.

What Is Mold?

Mold is a more invasive fungus that penetrates beneath surfaces and can cause significant structural damage and health problems. It thrives in areas with persistent moisture.

Identifying Characteristics of Mold

• Appearance: Fuzzy, slimy, or raised texture
• Color: Black, green, red, blue, or dark brown
• Location: Grows on and inside walls, ceilings, flooring, insulation, and wood structures
• Smell: Strong musty or earthy odor

Common Types of Household Mold

• Aspergillus – Found in HVAC systems, walls, and insulation
• Cladosporium – Grows on fabrics, carpets, and wood surfaces
• Stachybotrys (Black Mold) – Thrives on water-damaged materials; known for serious health risks
• Penicillium – Often found on water-damaged furniture and carpeting

Health Risks of Mold Exposure

Mold exposure can cause a range of health problems, especially for vulnerable individuals. Symptoms include:

• Chronic coughing and wheezing
• Nasal congestion and sinus issues
• Eye and skin irritation
• Asthma attacks or worsening respiratory conditions
• Headaches and fatigue
• In severe cases, neurological symptoms and immune system effects

Who is most at risk?

• Children and elderly individuals
• People with asthma or allergies
• Those with weakened immune systems
• Individuals with chronic respiratory conditions

If anyone in your household experiences unexplained respiratory symptoms, mold could be the cause.

When Can You Handle It Yourself?

Mildew and small mold spots can often be addressed with DIY methods if caught early.

DIY Cleanup Is Appropriate When:

• The affected area is smaller than 10 square feet
• Mold is on non-porous surfaces (tile, glass, sealed countertops)
• There's no water damage or structural involvement
• You don't have respiratory health issues

DIY Cleaning Tips:

• Wear gloves, goggles, and an N95 mask
• Use a mixture of water and detergent or a commercial mold cleaner
• Scrub the surface thoroughly and dry completely
• Improve ventilation to prevent recurrence

Caution: Never mix bleach with ammonia or other cleaners—the fumes are toxic.

When to Call a Mold Remediation Professional

Some situations require professional intervention. Call a mold remediation company if:

• The mold covers more than 10 square feet
• Mold is growing inside walls, ceilings, or HVAC systems
• The mold resulted from sewage or contaminated water
• You see visible structural damage
• Mold keeps returning after cleaning
• Household members are experiencing health symptoms

What Professional Mold Remediation Includes:

• Comprehensive inspection – Identifying all affected areas, including hidden mold
• Containment – Sealing off the area to prevent spore spread
• Air filtration – Using HEPA filters to capture airborne mold spores
• Safe removal – Removing contaminated materials following industry protocols
• Cleaning and sanitization – Treating all surfaces to eliminate remaining mold
• Prevention recommendations – Addressing moisture issues to stop future growth

How to Prevent Mold and Mildew Growth

Prevention is the best defense against mold and mildew. Follow these tips:

• Control humidity – Keep indoor humidity below 60% (ideally 30–50%)
• Fix leaks promptly – Repair plumbing, roof, and window leaks immediately
• Improve ventilation – Use exhaust fans in bathrooms and kitchens
• Dry wet areas quickly – Clean up spills and flooding within 24–48 hours
• Use mold-resistant products – Consider mold-resistant drywall and paint in moisture-prone areas

Don't Guess—Get It Checked

While mildew is a common nuisance that's easy to clean, mold is a more serious problem that can damage your home and harm your health. Knowing how to tell the difference—and when to call a professional—protects your property and your family.

If you're dealing with mold that's spreading, recurring, or causing health symptoms, don't take chances. Contact a mold remediation professional for a thorough inspection and safe removal.

Concerned about mold in your home? Schedule a professional mold inspection today.