What Does Mold Smell Like? Signs You May Have A Problem

By: Licensed Mold Assessor Brad Fishbein

February 4, 2023

I think you'll agree with me when I say: It's very startling to have a musty or unpleasant odor.

Most of the time, homeowners think they have a serious mold problem if they think they smell mold.

But Is it mold?

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Musty odors present in the house do not directly indicate you are smelling mold.

There are also a variety of other odors that can easily be confused with mold odors, however, if you do have an odor caused by mold, it was caused by one major thing:


Mold can't grow and thrive without it…

The smell of mold has an extremely distinct odor. If this is something you think you are dealing with, you will want to go through this entire article.

And if the smell is not mold that's affecting your air quality, you will be able to properly diagnose it and get rid of the odor.

That's right, no more people covering their noses when they come into your home!

Can Mold Smell?

Yes, mold certainly can smell. Have you ever walked into a room and gotten a weird, musty smell? Certain types of mold release gross Microbial Volatile Organic Compounds (MVOCs) that can cause moldy odors. The mold itself does not smell bad. It is the off-gases affecting the air quality that is let off by mold growth.


You read that right.

What Does Mold Smell Like?

Mold smells like a unique and often unpleasant odor that many people describe as musty, stale, and earthy. It's kind of like the smell of wet socks or old wood that's been left out in the rain. Those are some of the most common characteristics of mold smells, although they can vary. If you walk into a room and it smells like a stuffy attic that hasn't been aired out in a while, mold could be the cause.


These unpleasant odors are often described as wet, musty, and similar to the smell of decay or garbage.

The smell of mold can vary between different species and even within a single species, depending on things like its stage of growth and reproduction.

Some molds have an earthy smell, while others can smell sweet or even like fermented alcohol.

But wait, it gets even grosser: It smells like rotten meat. Or even wet socks!

The smell of black mold is often similar to a musty basement or rotting leaves, but keep in mind that there are many other types of mold that can be found in homes and buildings.

Musty smells may also be just high relative humidity in the home. If you have your windows open, are not running your air conditioning system frequently, or run your air conditioning system improperly, it may lead to a foul odor.

What Are MVOCs?

MVOCs are microbial volatile organic compounds (MVOCs), which causes some molds to smell. Traditional volatile organic compounds (VOCs) are mainly industrial-made chemicals with low molecular weights, high vapor pressure, and low water solubility. MVOCs are released from the metabolic processes of decay agents like fungi, bacteria, and biofilm. The off-gassing of MVOCs includes a wide range of alcohols, ketones, aldehydes, esters, carboxylic acids, lactones, terpenes, aromatic hydrocarbons, sulfur, and nitrogen compounds. Source

You don't need to know scientifically how MVOCs are formed, however, you must know it is caused in most cases by water-damaged porous materials. This could mean drywall, clothes, flooring, etc.

The bottom line is this:

If you have had a leak in your home that was not dried up properly or maybe a hidden leak that led to mold growth…

You Smell Mold - What Can You Do?

If you have a mold smell, it is important to take action to address the issue as soon as possible. It is recommended to take the following steps if you smell mold:

  1. Locate the source of the mold growth: Identify the areas where the moldy smell is strongest and try to locate the source of the moisture or water that may be contributing to the growth of the mold.

  2. Moisture or water: Once you have identified the source of the moisture or water, it is important to repair or fix the problem to prevent further growth of the mold.

  3. Remove the visible mold: Figure out the moisture source. If the affected building material is less than 10 sq feet you can remove it yourself. If it's a larger area, a mold remediation professional should be contacted.

  4. Use dehumidifiers: Use a dehumidifier to remove moisture from the air.

  5. Ventilate the area: Open windows and use fans to help circulate fresh air and reduce the musty smell. Ensure there is no leak as this can actually lead to mold growth.

  6. Check your attic: Make sure there are no leaks in your attic whether it be a roof leak or leaky ductwork.


Dealing With Musty Mold Smell That You Can't Find

If you suspect that there may be mold present in your home or workplace, but you are unable to see it, there are a few steps you can take to try to locate the source of the mold and address the issue:

  1. Keep your eyes peeled for any visible signs of mold. These can include white, brown, or green splotches and signs of decay. Be sure to check out moisture-prone areas like the basement, attic, and bathroom.

  2. Check for hidden sources of moisture or water. Mold loves nothing more than a damp and humid environment, so be on the lookout for leaks in the roof, walls, or plumbing. A moisture meter can be a great tool to help you locate hidden sources of moisture.

  3. If all else fails, don't be afraid to consult with a professional. Mold remediation specialists and healthcare professionals can help identify the type of mold present and whether it's a known health hazard. It's always better to be safe than sorry!

Is Mold Odor A Health Concern?

The musty odor or stale smell of mold is often one of the first indicators of its presence.

Musty odors do not indicate you have mold growing.

Yes, mold can be a health concern.

Mold produces allergens and irritants that can cause allergic reactions in sensitive individuals.

These reactions can include hay fever-type symptoms such as sneezing, a stuffy or runny nose, red eyes, and skin rash.

Mold can also cause more serious health effects, such as asthma attacks in people with asthma or allergies to mold. For individuals with compromised immune systems or people with chronic lung disease, mold can cause infections in the lungs.

Toxic mold can be a real health hazard, so it's important to speak with a licensed medical professional if you have any concerns.


How Else Can I Tell if I Have Mold?

Besides the smell of mold, there are a few ways to find if you have mold.

  1. Water damage or leaks: Mold loves moisture, so if you've had any recent water damage or leaks in your home, it's a good idea to check for a damp surface. Just follow your nose - the musty, stale smell of mold is a dead giveaway.

  2. Physical symptoms: If you're experiencing symptoms like sneezing, a stuffy or runny nose, coughing, itchy eyes, and watering eyes, mold could be the culprit.

  3. Visible growth: If you see any dark, fuzzy, or slimy growth on surfaces in your home, it's probably mold.

  4. Mold Test Kit: If you're not sure whether or not you have mold, you can always invest in a mold testing kit. These kits are readily available and relatively cheap, so you can get a definitive answer without breaking the bank.

  5. Profession Mold Inspector: You can consult with a professional who can perform a mold inspection and identify the type present in your home. And if you're really worried about a possible mold allergy, your doctor can offer skin or blood tests to give you peace of mind.

  6. Have HVAC System Checked: Sometimes the odor you are smelling is mold but it's not from a leak. It's growing in your air conditioning system. It's important to have your HVAC air handler and ductwork checked and cleaned as needed. Ensuring you keep your HVAC system clean will help keep the good air quality in the home.


How To Get Rid Of The Mold Smells

Getting rid of the mold smell in a home can be accomplished by a process known as mold remediation. Mold remediation will get rid of the odor by not only removing the mold-damaged materials but also sanitizing the home through a process called micro-cleaning.

In most cases, this will need to be done by a licensed professional. Here's a great guide to determine whether you need mold remediation or you can do it yourself.

Once mold remediation is completed, the odor should be gone.

If the smell still lingers within the home it could indicate all the mold has not been removed.

Dead mold spores can house themselves in your carpets, mattresses, and other furnishings which may need to be treated or discarded.

Your clothes in most cases can be put in a traditional laundry machine. Sometimes it may be necessary to put the clothes through two cycles.

Meet the author: Brad Fishbein is an ACAC council-certified Microbial Investigator. In the fall of 2012, he became a Licensed Mold Assessor in the State of Florida through the Department of Business & Professional Regulation. Brad has helped homeowners with over 5,000 successfully completed Mold Inspections since 2009.

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