Mold and mildew are both fungi that thrive in damp spaces, and the terms are often used interchangeably. But there are real differences in how they look, how deep they grow and how they should be handled. Knowing which one you are dealing with helps you decide whether a quick cleaning will do or whether you have a bigger moisture problem.
What Is Mildew?
Mildew is a type of mold that grows flat on the surface of moist areas. It is commonly found on shower tile and grout, window sills, bathroom ceilings, and damp fabrics or paper.
- Color: usually white, gray or light yellow, sometimes turning darker
- Texture: powdery or fluffy
- Growth: stays on the surface and is easy to wipe away
What Is Mold?
Mold is a broader group of fungi that can penetrate into porous materials like drywall, wood, carpet and insulation. Once it roots into these materials, it cannot simply be wiped off.
- Color: green, black, blue, brown, white or even pink or orange
- Texture: fuzzy, slimy or raised
- Growth: spreads into and beneath surfaces, often in hidden areas
Learn about specific species in our guide to common types of mold.
Mold vs. Mildew at a Glance
- Appearance: mildew is flat and powdery; mold is fuzzy or slimy and raised.
- Depth: mildew sits on the surface; mold grows into materials.
- Location: mildew favors bathrooms, windows and fabrics; mold appears on drywall, wood, ceilings, basements and inside walls.
- Cleanup: mildew usually cleans up with household cleaners; mold on porous materials often requires removal.
- Cause: both indicate moisture, but significant mold growth often points to a leak or water damage.
The Simple Test
Dab the spot with a cotton swab dipped in diluted household bleach. If it lightens within a minute or two, it is likely mildew. If it stays dark or comes back quickly, it is more likely mold. This is a rough indicator only, and you should wear gloves and ventilate the area.
Health Effects
Both mildew and mold can trigger allergy-like symptoms such as sneezing, coughing, congestion, and eye and skin irritation, and both can aggravate asthma. Larger mold problems typically release more spores and pose a greater risk, especially to children, older adults and anyone with respiratory issues. See our guide on black mold health risks.
How to Clean Mildew
- Ventilate the room and wear gloves, eye protection and a mask.
- Scrub with a household cleaner or detergent and water.
- Rinse and dry the surface thoroughly.
- Never mix bleach with ammonia or other cleaners.
When It Is Mold and You Need Help
Call a professional mold remediation company if:
- The growth covers more than about 10 square feet
- Mold is on drywall, ceilings, wood framing, insulation or carpet
- The growth followed a leak, flood or other water damage
- You smell mold but cannot find the source. Check our list of signs of hidden water damage.
- It keeps returning after cleaning
How to Prevent Mold and Mildew
- Keep indoor humidity between 30 and 50 percent
- Run exhaust fans during and after showers and cooking
- Fix leaks right away and dry wet areas within 24 to 48 hours
- Do not leave wet towels or laundry sitting
- Improve airflow in closets, basements and crawl spaces
Mold vs. Mildew FAQ
Is mildew less harmful than mold?
Mildew is generally easier to deal with because it stays on the surface, but both can cause symptoms in sensitive people.
Can mildew turn into mold?
Mildew is itself a type of mold. Surface growth that is ignored in a persistently damp area can spread, and conditions that support mildew also support more invasive mold.
Does vinegar kill mildew?
Many people use white vinegar to clean surface mildew on non-porous surfaces. It will not fix mold that has grown into porous materials, and it does not address the moisture source.
Need Help Now? Longview Restoration Is Available 24/7
Longview Restoration is a locally owned, IICRC-certified water, fire, mold and storm damage restoration company. Our technicians respond day or night, document everything for your insurance claim, and restore your property to preliminary condition.
- Call 24/7: (615) 903-0053
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- Learn more: Water damage restoration · Mold remediation