How to tell if it's mold or mildew?

Author: Prof. Abigayle Gulgowski  |  Last update: Saturday, October 4, 2025

Mildew has a gray, white or light brown color and generally rests flat on the surface of a moist area. It has a powdery appearance that may have a distinct, foul odor. Mold has a fuzzy, raised appearance and in unaired areas has a strong, musty smell. It often appears in darker shades of black, green and red.

How do you tell the difference between mildew and mold?

Mildew is a surface fungi identified as a patch of gray or white fungus lying on the surface of a moist area. Mildew is easily treated with a store-bought cleaner and a scrubbing brush. Mold can have colors that range from black to green and is often the result of a much larger infestation.

How do you test for mildew or mold?

To test for mold and mildew, apply a few drops of bleach onto the affected area and then wait a few minutes. If the area lightens up or disappears, it's likely mildew. If the area remains dark or unchanged, it's likely mold.

Does a musty smell mean there is mold?

A moldy or musty smell is frequently associated with the growth of mold or mildew. These smells are due to microbial volatile organic compounds (mVOCs) being released into the air. The mVOCs are produced by mold and as it grows, they can produce strong smells alerting you of mold or mildew growth.

How long before mildew turns to mold?

Given the proper conditions, mold will start to germinate and grow as early as 24 hours after encountering the moisture source. In 3 to 12 days, the mold spores will colonize. In 18-21 days, the mold can become visible. In general, the longer that moisture is present, the greater the chance for mold to grow and spread.

Mold vs. Mildew: What's the Difference?

What are the 10 warning signs of mold toxicity?

Although symptoms can vary, the most common symptoms seen in people exposed to mold indoors include:
  • Nasal and sinus congestion.
  • Eye irritation, such as itchy, red, watery eyes.
  • Wheezing and difficulty breathing.
  • Cough.
  • Throat irritation.
  • Skin irritation, such as a rash.
  • Headache.

Will a dehumidifier help with mold?

Mould will easily grow and spread if the right conditions are present. So, dehumidifiers don't kill mould, but they can help to prevent it from growing inside your home by reducing humidity. However, the best way to deal with it is to get rid of its source.

How can you tell if a house has mold?

Warning Signs of Mold
  • Strange Musty Odors. One of the first warning signs of mold is a stale, musty odor permeating your home. ...
  • Asthma or Allergies That Worsen Indoors. ...
  • Chronic Fatigue and Headaches. ...
  • Recent Water or Moisture Issues. ...
  • Dark Stains on Walls or Ceilings. ...
  • Peeling Wallpaper. ...
  • Unusual Pet Behavior.

What can smell like mold but not be mold?

Check humidity: Musty odors can often be due to excess moisture. Use dehumidifiers to reduce humidity, especially in rooms such as the bathroom, basement or other damp areas. Cleaning: Thorough cleaning is crucial. Clean carpets, curtains, furniture and other surfaces that absorb moisture regularly.

What is the best solution to clean mold?

Chemical or Natural Mold Cleaners
  • Use undiluted white vinegar on hard surfaces in kitchens and baths. Apply it directly to the mold.
  • Make a bleach solution to kill mold. Mix one cup of bleach in a gallon of water. ...
  • Mix a 50/50 solution of ammonia and water. Spray on the surface.

How to tell if mold is behind walls?

How to Detect Mold in Walls
  1. Water stains.
  2. Dark rings.
  3. Discoloration.
  4. Deterioration like peeling, bubbling, or cracking of the paint or wallpaper.

Can I do a mold test myself?

Mold testing kits are available at most home improvement stores or online retailers, although not all tests are the same. There are some kits that only test for the presence of mold on surfaces, while others collect or grow samples of the mold that may be in your home.

What does the CDC recommend for cleaning up mold?

Mold can be removed from hard surfaces with household products, soap and water, or a bleach solution of no more than 1 cup of household laundry bleach in 1 gallon of water.

Can mold inside walls make you sick?

Can Mold Inside Walls Make You Sick or Does It Need to Be Exposed? Yes. Even if you can't see it, mold can make you sick. Spores can spread throughout your home, even from relatively contained areas like inside the wall.

How do you rule out mold?

Other Ways on How to Test Mold in Your Walls, Basement & Indoor Air. Aside from visible mold spores, looking for leaks and other sources of moisture is another way to test your home for mold. Using mold testing kits for small infestations and professional testing for severe ones are the most effective ways.

What comes first mold or mildew?

Mildew is a fungus that looks like flat, white, or gray powdery dots in its early stages before turning brown. It is an early stage of a mold growth colony and often needs moist conditions.

What are signs of mold sickness?

If you have a mold allergy, your immune system overreacts when you breathe in mold spores. A mold allergy can cause coughing, itchy eyes and other symptoms that make you miserable. In some people, a mold allergy is linked to asthma and exposure causes restricted breathing and other airway symptoms.

What to do if you smell mold but don't see it?

When a homeowner smells mold but visual clues are invisible to the naked eye, then mold testing can be performed by a professional to locate the colonies. A mold testing kit can also be inexpensively purchased from the local hardware store and utilized by the homeowner.

Are there mold detectors?

The Biomatrix mold monitor is more than the most technologically advanced smart home mold detector on the market. With the purchase of a Biomatrix device, your system will be monitored by a team of specialists, ensuring that your home is scanned for signs of trouble 24/7.

How do you test your house for mold in the air?

The two most common methods used to identify a mold problem are mold test kits or air testing sensors. These kits include the necessary air test devices, chemical strips, or Petri dishes and are available at department stores or online. They'll also come with an instruction manual for any brand-specific guidelines.

How long does it take to get sick from mold exposure?

According to the CDC, people usually experience their first symptoms within 2 to 9 hours of their first exposure. On the other hand, some people could go for weeks or months before feeling sick if their exposure is limited enough. This is why it is also important to check damp, dark areas of your home for mold.

What does harmless black mold look like?

Although the name implies a uniform coloring, black mold may appear black, dark green, or dark brown. It typically grows as a cluster of round spots with a distinctly wet, slimy appearance. As stated, black mold typically appears fuzzy or furry.

Does DampRid get rid of mold?

DampRid's Odor Eliminator products don't just mask odors, they eliminate them by breaking up their molecular structure. And DampRid can help protect your home against moisture damage, solving many mold, mildew and odor problems.

Can an air purifier remove mold?

Your air filter can help to purify the air, removing tiny mold spores. This can be a tremendous help, and soon you'll start to feel more comfortable. Note that not every air purifier can remove and purify mold; you should check to make sure that your air purifier can do the job.

How to stop mold in a house?

How to reduce condensation
  1. pull wardrobes and furniture away from walls, and keep tops of wardrobes clear, to allow air to circulate.
  2. close doors and open windows when cooking.
  3. keep lids on saucepans when cooking.
  4. keep bathroom doors closed when bathing, and open windows slightly afterwards.

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