Mold Odours: What Does Mold Smell Like?

Ever smell something “off” inside your home or business? It could very well indicate the presence of mold. In fact, when we conduct professional mold testing, the smell is often the first giveaway! With that said, follow your nose and use it as a natural alert to the developing risk.

Most mold in homes is hidden in walls, attics or other places where it can’t be easily seen. Mold spots typically become visible on the outside of a wall only after weeks, months or even years of contamination. The eyes are therefore not very useful or accurate for detecting mold.

Luckily, mold smells are much quicker to appear than any visible signs of contamination. While mold smells are unpleasant, they are actually a good thing. They alert homeowners of an existing mold infestation that needs immediate attention.

In many cases, your sense of smell will be your most useful weapon in early mold detection and prevention of property damage.

mold odours

How can you detect mold smells?

The obvious answer to this question is: with your nose. However, in order for your nose to be effective, you have to be able to identify mold smells.

So what exactly does mold smell like? The answer is more complex than you might think.

There are thousands of species of mold, each with different colours, textures and, of course, odours. Some molds produce earthy smells, others produce sweeter smells and some even smell like fermenting alcohol or rotting meat.

hidden mold spores
hidden mold spores

Smells don’t only vary between mold species. A single species can produce wildly different smells depending on where it is in its cycle of digestion, growth and reproduction.

It’s important to keep this variation in mind when you try to detect potential mold smells in your home. Many people expect mold to smell only one way, so when they don’t notice this smell, they ignore other odours that can be caused by mold. Remember, you aren’t searching for just one particular smell!

What does mold smell like?

Despite the broad range of odours mold can give off, there are ways to distinguish those produced by mold from other types of smells. Mold smells are a bit like cheese in that they can vary a great deal but all share similar characteristics.

Some smell sharp, like aged cheddar, while others, like mozzarella, have softer smells. But despite this variation, we all know what cheese smells like.

Mold smells are usually described as pungent, musty, and moist. If you notice any smells with these characteristics, you should investigate immediately because they might be caused by mold!

What causes mold smells?

Many people believe that all mold smells are caused by mold spores, but this is not the case. While some mold smells are caused by mold spores, most mold smells are caused by microbial volatile organic compounds (MVOC), which are chemicals produced by mold’s various biological processes. They could be byproducts of the mold’s digestion, growth or reproduction. And depending on where the mold is in its life cycle, it may produce different odours or seemingly no odours at all.

black mold inside kitchen cabinet
hidden black mold inside kitchen cabinet

People sometimes think that if they can’t smell the mold, then it can’t harm them. This, however, is completely false. Most health risks of mold are caused by mold spores, while most mold smells are produced by MVOCs. During a mold colony’s reproductive www, it produces fewer MVOCs and more spores, so a mold colony is actually most harmful when it is least smelly.

While mold odours are a great early warning of mold growth, you should avoid relying solely on your sense of smell to detect potential mold growth in your home. The only way to really be sure that your home is free of mold is to have it inspected by qualified mold professionals. These professionals can use sophisticated detection methods, such as laboratory air testing and surface sampling, which are thousands of times more sensitive (and accurate) than your sense of smell.

At Mold Busters, we offer a range of inspection services, including virtual inspections and mold inspection and testing in Ottawa.

Are mold smells harmful?

On their own, mold smells aren’t especially harmful. However, they are an indicator of a mold problem, which could be a threat to your health if left unaddressed.

Depending on the species of mold, the amount of spores you’re exposed to, and the duration of exposure, mold can cause a number of health problems. The symptoms of mold exposure can be mild, such as headaches, nausea and minor irritation in eyes or lungs. Mold symptoms can also be very serious, causing potentially fatal allergic reactions, cancers, lung infections and other serious health issues.

Because the health risks of mold exposure range from mild to life-threatening, it’s best not to take any chances. Eliminating all sources of mold in your home is the surest way to protect yourself from the toxic effects of mold.

fungal growth in basement
fungal growth in basement

How to get rid of mold smell?

You should avoid the temptation to tackle mold smells with scented cleaners and air fresheners. It’s easy and inexpensive, but it also happens to be very ineffective. Cleaners and air fresheners may temporarily cover up the smell of mold, but they won’t solve the problem or stop the growth of mold.

The size of a mold colony will likely increase if all you are doing to address mold odours is to cover them up with scents. And while mold smells can be supressed with air fresheners, the harmful health effects of mold cannot. So while you cover up the problem with artificial scents, you will continue to be exposed to hazardous mold spores.

The only way to get rid of mold smells for good is to eliminate the mold colonies causing them in the first place. For large colonies covering more than 10 square feet, Health Canada recommends hiring mold remediation professionals. Our mold removal services are designed to do just that, ensuring a safe and healthy environment in your home or business.

However, for small colonies, it is possible to remove them safely and effectively on your own, so long as you have all the proper equipment and take the appropriate precautions:

  1. Before you tackle the removal of mold on your own, it is important to protect your lungs. Mold spores are light and the slightest disturbance can make them airborne. To prevent harm to your lungs, you should wear a mask or a respirator. It is also a good idea to wear safety glasses to protect your eyes.
  2. Mold is also very good at clinging to clothes and fabrics, so it is important to prevent spores from spreading to other areas of your home by wearing a plastic hazmat suit. Keep in mind that many clothes, especially if they are high in cotton, can become a breeding ground for mold.
  3. Once you have taken proper precautions, you can prepare the cleaning solution you’ll use to remove the mold. Depending on the area and the size of the colony, you can use a vinegar or bleach solution or a specialized mold cleaner. Scrub the affected area with the solution and then pat dry once you’re finished. Be sure to throw out any cloths or sponges you used for cleaning because they can easily become a breeding ground for mold.

Why should you hire professionals to get rid of mold smell?

If all of that sounds complicated and time-consuming, that’s because it is. Contrary to popular belief, mold is actually very difficult to clean up yourself. Mold is persistent and will grow back if it is not completely eliminated. More often than not, cleaning up mold without the proper experience or equipment just makes the problem worse. Mold spores spread easily through the air to other locations if disturbed by cleaning, so if you don’t do it right, you might wind up with three, four or even five more colonies in the long run.

mold in crawl space
hidden mold in crawl space

And if you only clean up mold that is readily visible, then you are likely missing even bigger mold colonies that are hidden from view. This hidden mold will continue growing and spreading spores, so you might see mold spots return weeks after you cleaned them up!

It’s also important to keep in mind that mold cleanup on its own doesn’t fix the problems that caused the mold to grow in the first place. You could have problems with your insulation, moisture build-up from leaking pipes or countless other contributing factors for mold. If these problems aren’t addressed, then you can expect to see mold return after cleanup.

For all of these reasons and more, it is best to hire qualified mold remediation professionals to remove larger mold problems. They will conduct a thorough inspection prior to the remediation to identify the extent of the contamination and plan for a safe and effective removal process. Our teams in Montreal and Ottawa are equipped with the latest technology and training to handle mold issues of all sizes.

At Mold Busters, we use sophisticated air testing, infrared scanning, third-party laboratories and other techniques to detect mold throughout your house. Once the cleanup begins, we adhere to rigorous standards in all our practices to prevent cross-contamination. Our mold experts will also identify and address the moisture problem that led to the mold growth in the first place, thereby preventing the mold from returning after cleanup.


Mold smells are a nuisance, but a welcome one because they warn us of mold colonies in our homes before these colonies are visible. You should always take mold odours as a reason to investigate the problem further. Call Mold Busters certified mold professionals for help.

Published: April 18, 2019 Updated: April 10, 2020

John Ward

Written by:

Account Executive
Mold Busters

Fact checked by:

Mold Busters

Michael Golubev