The Big Difference Between Mold and Mildew 

Understanding the difference between mold and mildew is the best way to develop a strategy to keep your household safe from fungal threats.

Mold and mildew aren’t just ugly; they present several risks to you and your home. Left untreated, these fungi can cause structural damage and even cause severe damage to your health and the health of your loved ones.

While both mold and mildew share many common traits, each poses its own risks and can require a specific type of treatment.

Mold vs. Mildew: What’s the Difference?

Difference Between Mold and Mildew

Both types of fungi are very closely related. For example, they like to sprout in similar places and both give off a foul smell, but how they develop and grow is a crucial difference between them, as well as the danger they pose to you.  

On the one hand, mold grows in black or green patches that penetrate beneath the surface of the affected material, while mildew instead grows flat on the surface without penetrating the surface, making it much easier to remove.  

Mildew also presents a much lesser risk of damage to your health as well, and more of a threat to plants and crops. Of the many types of mold that can exist inside your house, some are extremely toxic to people and animals. 

While both fungi can thrive in the same types of warm, damp environments, you will more often find mold growing inside permanent structures like walls and flooring while mildew usually grows on smaller surfaces like paper and fabric.

Is it Mold or Mildew? 

Experts know how to deal with all types of household funguses, but you can try telling the difference between mold and mildew by yourself.

While each can appear anywhere from unsightly to grotesque, there are some key differences in their overall appearances.

Moldy wall
Moldy wall
Mildewed wall
Mildewed wall

Mildew most often grows in a flat pattern and appears in either of two forms: powdery or fluffy. You can identify it by its lighter appearance which is either white, gray, or a light yellow. However, mildew can turn black or brown over time. 

In contrast, mold usually appears fuzzy, hairy, or slimy, and often grows more irregularly than mildew. While it can rarely look white and gray, most molds are usually a darker color or have multiple colors, such as blue, green, yellow, brown, and black. Wooden surfaces covered in mold will often begin to rot.

Common Types of Mold 

There are over 10,000 types of mold that we know of that can grow indoors and threaten your home.

However, there are five of these types that we find are by far most common, and we are highly equipped to treat. 


It is a mold commonly found in buildings that have suffered water damage.

It grows in showers, under sinks, around windows, walls, doors and in a variety of places that can acquire moisture.

The mold can look black, grey or dark brown and has a wooly or string-like texture.

Alternaria is known to increase your risk of allergic reactions and cause asthma attacks and breathing issues.


It is the most common type of mold found insides houses in the U.S. and all over the world.

The mold can appear in a variety of colors such as grey, brown, yellow, green, white, or black, and usually grows on walls, insulation, paper products, and clothing.

Prolonged exposure to Aspergillus can range from lung infections to allergic aspergillosis, an immune response that can include fever, asthma attacks, and coughing up blood and mucus. 


It is different than most other types of mold because it can grow in cooler areas.

More often found in fabrics like carpets and curtains and wood surfaces like cabinets and floorboards, the mold often looks black or dark green.

While Cladosporium is not often directly toxic to humans, it has been known to cause severe respiratory and allergy issues in some people, as well as infections of the skin and nails. 


It is a little different type of mold that can thrive in even low humidity.

While often attributed to food spoilage, it can also be found growing in furniture, carpeting, insulation, wallpaper, mattresses, and other several other materials.

Its appearance can vary, but the mold usually looks blue or green and produces a strong odor.

Penicillium spores can easily spread from one area of your home to another and can cause lung issues like asthma and allergic reactions that increase in severity over time.

black mold on wall

“Black Mold,”

Scientifically called Stachybotrys Chartarum is named both after its appearance and its extreme toxicity, being the most dangerous of common household molds.

The airborne toxins it produces can cause a wide variety of ill health effects, from breathing issues and allergy symptoms to headaches, chronic fatigue, and fever.

Black mold has a characteristic dusty, earthy smell, like dirt or rotting leaves, and can appear in parts of your home that are particularly warm and humid.

Some of the common places where we find black mold are basements, crawlspaces, and air conditioning ducts.

Learn more about mold symptoms exposure.

The best way to find the presence of mold in your home is using a mold test kit or call for an expert.

If you’ve spotted mold in your home, it’s time to act quickly before the situation gets out of control.

Don’t take a chance on your home and your health.

Call a professional mold removal service, or if you don’t find one or find it too expensive, then you can do it yourself.

There are many great mold removal products on the market. Just grab one and take action against unsightly mold immediately.

Leave a Reply