What Does Mold Actually Smell Like?

What You Need to Know

• Newly formed mold has a distinctive earthy or musty smell.
• Different types of mold have different types of smells, including rotten wood and fermenting alcohol.
• Mold smells are consistent and can be very pungent. They can also irritate a home’s residents and make them sneeze
• Mold can be present even if there are no telltale scents in the home.
• If there is a smell of mold, it’s best to call a mold remediation professional to test the home.

Q. There’s a strange musty odor in my basement. I’ve opened the windows, but the smell won’t go away. Is it mold? What does mold smell like?

A: It’s one of the greatest fears for every homeowner: a mysterious, lingering, musty smell. Where did it come from? How did it get there? And how can you get rid of it? Homeowners may be on the right track if they start to wonder, “Does mold smell?” But mold can take on different smells and spread to different places, depending on its stage of growth and type. Homeowners need to know how to identify and remove mold, as well as how to prevent it from spreading and reappearing.

Here’s how to identify mold based on the smell it produces and what to do if you discover mold in your home.

Editor’s Note: If you are experiencing the symptoms of mold exposure, which includes coughing, sneezing, congestion, and shortness of breath per the CDC, it’s best to consult a medical professional.

Mold can have a musty or earthy smell, especially when it is just starting to form.

The smell of mold is typically described as “musty.” It’s a stale and damp scent that lingers in the air. It’s one of the first and clearest signs of mold or mildew. Some common mold varieties like black mold may also give off an earthy smell.

If the initial scent is not very pungent, then it’s likely that the mold has just started to form. Mold spores can start to form in as little as 24 hours in the right conditions, so within a day, that musty mold smell might be present in the home.

When this is the case, it’s best to immediately find the root of the scent and eliminate it. The quicker mold is removed, the less time it has to spread. Homeowners should know that, depending on the type that’s growing, the mold can also potentially be hazardous to their health.

According to David Harley, Certified Mold Inspector (CMI), Certified Mold Remediation Contractor (CMRC), and owner of AdvantaClean of Badgerland, not all molds are created equal. “All molds tend to be either allergenic, pathogenic, or toxigenic,” Harley explains. “Allergenic mold causes allergic reactions such as itchy, watery eyes; sneezing; and headaches. Pathogenic mold tends to cause issues for people that have certain sensitivities to mold or have compromised immune systems or chronic conditions such as COPD or asthma. Toxigenic mold tends to be toxic to humans regardless of any underlying conditions. The most dangerous mold for you is the mold that causes health issues for you.”

Homeowners may not know that they are sensitive to a particular mold until they come into contact with it. Harley cautions, “Since any mold can be potentially allergenic, pathogenic, or toxigenic, all mold should be treated carefully and by a professional.”

There are several types of mold, and each one has a different smell.

Different types of mold will have different smells. For example, black mold is one of the most common types of mold found in households. What does black mold smell like? For many people, it has the scent of a musty basement or rotting leaves. However, black mold is far from the only type of mold that can be present in the home. According to Victor Coppola, senior building biologist and founder of GreenWorks Environmental, LLC, the smell of mold could range from decaying meat to sweaty socks depending on its variety and the condition in which it grows. “Odors vary depending on a variety of things like moisture levels, food sources, location, [the presence of] other microorganisms (bacteria in particular), and where [the mold] is in its lifecycle. Most molds fall into a broad ‘damp-musty aroma’ category, but if a ‘sweaty sock’ aroma is also present, that would be the bacteria that cohabitate in that environment,” says Coppola. This, he explains, is due to the presence of microbial volatile organic compounds, or mVOCs.

Smelling mold but not seeing it might mean that it is growing somewhere hidden. So what does mold smell like in walls? “If it smells more like a ‘meaty-decay-musty’ fragrance, that is one of your more toxic black molds hidden in a wall cavity,” says Coppola.

The average homeowner may not be able to distinguish among mold’s various scents, and they shouldn’t risk extended exposure to do so. In any case, Coppola explains, “It’s more common to get a multitude of aromas all overlapping that we call a ‘cocktail effect’ that makes things even more complicated.” A mold removal professional will be able to better assess what kind of mold is present and how to handle it.

Mold odor can be very pungent, and the smell is generally consistent.

Those wondering how to get rid of mold smell should keep in mind that unless they are also getting rid of the mold itself, the smell is sure to stick around. When some homeowners smell mold, their first thought may be to open their windows to air out the odor and hope it goes away. However, even with the windows open and air circulating, the smell will still be there.

The longer the homeowner takes to address the smell, the more it will spread and the stronger and more pungent the odor will become. It’s important for homeowners to isolate the source of the smell as soon as possible. If left untreated, the mold could spread to new places, which can result in a longer and more arduous removal process.

A stale and damp smell in the air is often a telltale sign of mold.

No number of open windows or amount of air freshener can fully remove the odor created by mold. These quick fixes may temporarily mask the scent, but if left unchecked, the mold will continue to spread.

A damp smell is a common sign of mold because mold and mildew thrive on moisture. Spores of the mildew fungus will linger in the air until they find a damp, dark, warm area for them to multiply and spread. This is why most molds and mildew are typically found in a basement or bathroom setting, as there is plenty of moisture and these rooms tend to be darker for extended periods.

The smell of mold can resemble the smell that rotten wood produces, or it can smell sour and tangy like fermenting alcohol.

Homeowners who have spent a fair amount of time hiking or camping in the woods or have spent time doing yard work may find the musty, damp smell of mold familiar. But what does mold smell like in a house? Mold can often resemble the scent of rotting wood particles. While this smell is commonly found outdoors, if a homeowner notices it in their house, it is an almost definitive sign that mold is growing. Mold can also take on a sour or tangy smell that resembles fermenting alcohol.

The musty smell may irritate you and make you sneeze.

When mold is concentrated, sneezing and headaches are common symptoms that homeowners who may have a mold allergy can experience. Other common symptoms may include a runny nose, itchy throat, congestion, and dry skin. These symptoms are remarkably similar to that of seasonal allergies, also known as hay fever.

A mold allergy occurs when spores get into your nose and cause the symptoms. When they reach your lungs, they can also cause asthma. Sometimes these symptoms are delayed and may worsen over time.

If a homeowner is experiencing these symptoms more indoors than outdoors, it’s usually a sign they may have a mold allergy and that mold is present in the home.

Signs of water damage, even without a smell, could signal mold.

Unfortunately, if mold has only begun to form recently or is in a part of the home that isn’t visited often, it may go unnoticed. Parts of the home that have been affected by water damage or that tend to be damp are especially prone. According to Harley, attics and basements are prime candidates for mold since temperature changes between seasons can cause condensation to form. It also shouldn’t be assumed that any part of the home is immune to mold. “Mold can actually be found anywhere in the home,” says Harley, “Mold simply needs three things to grow: a temperature of somewhere between 40 and 100 degrees Fahrenheit; a food source of organic materials such as wood, paper, leftover food, [or] plant matter; and moisture. Moisture tends to be the wild card; in other words, if you can control the moisture, you can control the mold.” Harley’s recommendation is to keep the humidity level in the home relatively low using one of the best dehumidifiers for your home.

Some forms of household mold are toxic and may cause additional health complications.

The biggest reason homeowners should take care of mold as soon as they smell it is that some forms of mold, such as black mold, are toxic, and therefore could be potentially hazardous and should be removed as soon as possible. Toxic mold typically causes neurological symptoms, such as dizziness, decreased focus, headaches, and memory loss. Homeowners experiencing any of the above symptoms regularly may want to seek medical attention and have a professional assess the mold situation in their home. The cost of mold remediation is a small price to pay when it comes to one’s health and the health of their family.

A musty smell doesn’t always signify the presence of mold.

If a homeowner detects an unpleasant odor in their home but can’t locate where it is coming from, they shouldn’t start ripping up their carpet to look for mold right away. They should first check for other sources of the smell, such as a pile of wet laundry, an expired food item, or a pet that needs a bath, all of which could give off a similar musty stench. Bad odors in the home could also be a sign that the home’s plumbing has sprung a leak or the HVAC is in need of service. Googling “house smells musty but no mold” may yield more ideas of where the stench could be coming from. Once the homeowner has ruled out these other potential culprits, it may be time to get a mold inspection. While the average cost of a mold inspection may seem high, it will most likely be worth the investment.

What should I do if I smell mold in my home?

Once a homeowner has detected a mold smell somewhere in their home, they need to very carefully try to locate where the growth is coming from. Homeowners should wear a mask or respirator and put on gloves when they think they’re close to the source of the mold. Because mold likes to grow in a dark area, it may not be visible right away. A light source can help the homeowner look for surfaces that collect moisture, especially in corners and tight spaces without much airflow.

Once the scent and its source have been located, the homeowner can assess the severity of the mold. If they decide the problem is small enough to tackle on their own, they can follow steps to thoroughly clean the affected area. But homeowners should also keep in mind that without proper remediation, mold is likely to return again and again. Letting a professional take care of the problem will always be the most effective way to keep homeowners and their families safe from mold exposure. If anyone in the home has been experiencing symptoms of mold exposure or has health conditions that might be worsened by it, it’s best to call one of the best mold remediation companies (such as ServiceMaster Restore or ServPro) right away.

After the mold is eliminated, homeowners can take different precautions to prevent it from returning. Coppola cautions, “As we are dealing with opportunistic organisms, you always need to be monitoring your environment to ensure conditions don’t return that would invite regrowth of the organism.” One effective method is to install dehumidifiers in any area where humidity is an issue. Having a ceiling fan on in a room that is mildew prone or that smells like mildew is another way to keep the area dry and prevent the spread.

Understanding how to identify mold by scent can help homeowners detect a mold or mildew problem before it gets worse, and it can potentially save them from negative health symptoms and home damage.