What Does Mold Smell Like: Unraveling & Conquering the Aroma

Mold can produce a variety of distinct odors depending on the type of mold, age of growth, environmental conditions, and type of material/surface it is growing on. While mold smells can range greatly, some common scents associated with mold include earthy, musty, rotten, or stale odors. Identifying the specific smell can help determine the mold variety and suitable removal methods.

How Do I Know If I’m Smelling Mold?

If you notice a persistent musty or earthy odor in your living space, it could be an indication of mold. Mold emits a distinct smell, often described as musty or damp, which is a result of volatile organic compounds (VOCs) released during its growth. If you can’t visually identify mold but detect an unusual odor, it’s advisable to investigate areas prone to moisture, such as basements, bathrooms, or areas with a history of water damage.

What Does Mold Smell Like?

Musty Scents

Alternaria mold, one of the most common indoor molds, produces a strong musty smell reminiscent of old clothes or wet towels left in the washer too long. This prevalent smell is due to the mold’s production of volatile organic compounds (VOCs) like octenol, hexanol and nonanol which all contain musty odor profiles. These VOC metabolites allow the mold smell to spread easily through air circulation from a relatively small Alternaria source.

Other molds that can produce similar musty smells are Aspergillus, Penicillium and Fusarium species. They tend to smell stronger with increased moisture and humidity in the air and dissipate more as conditions become drier. The musty odor tends to intensify the longer the mold grows undisturbed in an environment.

Earthy Smells

Stachybotrys chartarum, known commonly as black mold, produces a highly distinguishable earthy smell, especially when the mold colony growth is extensive. Aspergillus versicolor is another mold variety that smells earthy and is often indicative of moisture issues indoors.

The earthy type of mold smell is created by a compound called geosmin that the mold produces during metabolic processes. Geosmin is distantly related to substances that result in the earthy smell of soil and beetroots. When smelling a strong earthy odor spreading inside a home or building, it generally signals a hidden mold problem requiring thorough inspection and elimination.

Rotten, Decay Scents

Mold growth on wood often presents as a rotten, decayed, or dead-animal type of odor. This is because the mold organisms consume the wood cellulose structure as a food source. Trichoderma mold species notably produce these signature rotten smells quite rapidly. Wet, rotting drywall also has a very similar pungent odor due to the decomposition processes occurring.

The rotten mold smell tends to become worse when the growth spreads to carpeting, mattresses, cloth furniture, and other porous materials made of natural fibers. Mold can decompose such materials and emit stronger decaying smells the longer it goes unmitigated. Proper drying out and cleaning or complete replacement is required to get rid of the smell permanently.

Fruity or Sweet Smells

While less common, some molds demonstrate distinctly sweet, fruity, or floral scents when colonies proliferate. For example, the fungus Antrodia vaillantii, which causes brown rot decay in wood, produces an identifiable scent of sweet coconut as it destroys the wood cells.

Meanwhile, Scopulariopsis mold varieties have musty earthy tones combined with hints of anise or licorice. The fungi’s complex volatile compounds interact to produce sweet notes. Usually, these types of mold with sugary notes concentrate in processed or artificial materials, such as painted drywall or particle board, rather than natural wood.

Factors Affecting Mold Odors Several key factors cause differences in mold smells:

  • Mold Type – There are thousands of known mold species and each produces its own unique odor signature through complex metabolic processes and mycotoxin production. Rare molds can smell quite unusual or even appealing compared to common moldy smells.
  • Age & Size of Growth – As mold colonies expand over time, they can emit exponentially more noticeable odors. The intensity of the smell typically correlates directly with the extent of uncontrolled mold growth.
  • Material Substrate – Mold will create varying scents based on what surface/material it is decomposing as a nutrient supply. Natural fibers tend to emit stronger odors more rapidly once infected with mold.
  • Exposure to Air – Enclosed mold trapped within walls or under materials smells less until released into open airflow. Upon exposure, smells can discharge rapidly to new intensities based on altered chemical volatility.
  • Environmental Conditions – Changes in temperature, humidity, sunlight, air supply, and occupancy all impact chemical emissions from mold resulting in differences in smell potency pending such factors.

Health Effects

In addition to producing unpleasant odors, mold can also cause allergy symptoms or respiratory issues when inhaled by sensitive individuals. Possible health effects include:

  • Wheezing, chest tightness
  • Sore throat, congestion
  • Eye & skin irritation
  • Coughing
  • Headaches
  • Fatigue

If mold smells are noticed indoors, it is critical to test the air and identify all contaminated areas promptly. Mycotoxins and mold particles when airborne can get inside the lungs and sinuses leading to inflammation or dangerous respiratory diseases. Seek professional mold inspection and remediation as soon as possible wherever smells are continuously problematic. Practicing good indoor air quality and moisture control habits can help avoid mold growth issues down the road.

Identifying the Smell

Pinpointing the exact type of musty, earthy, or rotten scent caused by mold assists in narrowing down the probable source. Write down any descriptive words that characterize the odor such as sweet, sour, bitter, floral, fruity, stale, dusty, etc. Also note if the smell changes intensity depending on the time of day, weather, or room conditions. recording specifics helps investigators locate the origin.

Here are some common identifying mold smells:

  • Wet dog, socks, towel – Alternaria, Aspergillus
  • Old dirt, beetroot – Stachybotrys, Aspergillus versicolor
  • Rotting wood, corpse – Trichoderma, carpets, drywall
  • Coconut, anise – Antrodia vaillantii, Scopulariopsis
  • No odor – Cladosporium, Aureobasidium

Testing for Mold

To validate the presence of problematic mold growth, indoor air quality testing is recommended. Sampling for mold involves inspectors using specialized equipment to catch spores, metabolites, and particles for lab analysis. Common test methods include:

  • Air Testing – Samples airborne mold levels using a cassette to capture particles for microscopic examination providing detail on the types and concentrations.
  • Surface Testing – Swab samples are taken directly from visible mold growth spots or potentially contaminated material and then examined by a mycologist to identify genera and toxicity.
  • Bulk Sampling – Lynette mold inspector cuts out a piece of wall cavity, insulation, or other building materials with suspected hidden mold for quantitative cultures to gauge the full extent of the contamination.
  • VOC Metabolite Testing – Air samples are analyzed for the unique mold volatile organic compounds like geosmin or microbial VOCs (mVOCs) consistent with fungal metabolisms to help locate sources.

Once positive mold specimens are classified taxonomically, the probable smells produced by each genre can be checked against existing scent observations. This mold matching assists remediators in pinpointing all related areas for treatment. Any zones exhibiting water leaks, condensation, or moisture enabled the mold and must be fully dried with repairs completed before rebuilding contaminated structures.

Mold Varieties & Associated Smells

Mold GenusCommon Smells
AlternariaMusty, old clothes
AspergillusMusty, earthy
PenicilliumMusty, stale
StachybotrysEarthy, dirt
TrichodermaRotten, decay
FusariumMusty, damp

Remediating Mold Odors

Once mold inspection confirms the type and location of contamination, addressing any resulting musty or rotten smells involves:

  1. Fix plumbing leaks, seal roofs, improve ventilation, and dehumidify to stop recurring mold growth.
  2. Remove mold from non-porous surfaces with HEPA vacuuming, followed by cleaning using hydrogen peroxide, vinegar, or detergents.
  3. Discard porous goods like drywall, carpet, and insulation that exhibit mold as smells may persist long-term.
  4. Treat remaining tiny mold residue or deeper structural infiltration using antimicrobial coatings to encapsulate spores.
  5. Install air scrubbers and negative air machines with high-quality HEPA filters during remediation to manage airborne smells through high ventilation.
  6. Employ fogging or thermal systems to treat whole rooms effectively. Repeat applications may be required.
  7. Seal off and ventilate work zones to avoid spreading spores and smells into unaffected areas.

With diligent, thorough remediation most moldy smells can be eliminated successfully. Prevent future growth by monitoring humidity levels and promptly fixing any recurrent moisture or leaks.


In conclusion, understanding what mold smells like is a valuable skill for homeowners. The distinctive musty odor associated with mold is a result of volatile organic compounds released during its metabolic processes. Early detection and proactive measures are crucial to preventing mold-related health issues and maintaining a healthy indoor environment.

With attentive mold detection and remediation, even long-standing or pervasive smells can be cleared fully from a home or building. Stay alert for any returning odors as a sign of lingering issues requiring additional repair and mitigation. Consistent moisture control keeps mold negligible.

If you mold smell issues inside your home, contact Southeast Water Restoration to get rid of the smell immediately.