Common Types of Mold (and How to Identify Them in Your Home)

Types of Mold

No home is completely mold-free. 

Regardless of where you live, there will always be trace amounts of mold somewhere indoors, typically in the form of microscopic units called spores that are invisible to the naked eye. However, under the right conditions, those spores may flourish and form colonies.

Unlike mold spores, mold colonies are visible. Which means if you spot a patch of mold somewhere inside your house, the problem has escalated. At this point, the safest course of action for you and your family is to call a professional who can assess the situation and help you develop a plan to remove the mold colony and prevent future mold growth

This blog will provide a brief overview of some common types of mold you may encounter in your home, plus a few key facts about mold to help you understand what you might be dealing with. 

The basics: What is mold? 

Mold is a type of fungi that is commonly found both outdoors and indoors. 

Because mold thrives on moisture, it will grow anywhere it can find wet or humid conditions. If you recently experienced water damage in your basement, for example, or if a broken pipe caused your kitchen to flood, you should definitely keep an eye out for mold growth. 

Mold is classified into one three main types (or groups) based on certain characteristics:

  • Allergenic mold: As you may have guessed by the name, this type of mold can cause allergy symptoms or aggravate existing allergies in some people. Such symptoms may include coughing, sneezing, watery eyes, runny nose, and trouble breathing.
  • Pathogenic mold: This type of mold is more concerning and could potentially trigger an infection in someone with a weakened or compromised immune system. 
  • Toxigenic mold: Toxigenic mold can be extremely harmful, even to healthy humans and animals. One example is Stachybotrys chartarum, otherwise known as toxic black mold. (Note: There are many types of mold that may appear black but are not Stachybotrys chartarum, which is another reason why you should always consult a specialist.) 

Mold vs. mildew

Are mold and mildew the same thing? Actually, no. 

While the two have several similarities—both are fungi, both love moisture, both grow on a variety of surfaces, and both can cause health problems—their primary differences are in the way they look, how they grow, and where you might find them

  • Mold can come in a variety of colors, while mildew is typically white or light gray, sometimes turning yellow or brown. 
  • Whereas mold will penetrate deeply into a material (such as wood or drywall), mildew has shallow roots and stays on the surface, often making it easier to clean. 
  • Mold grows in large spots or fuzzy patches, while mildew is generally powdery in appearance, often looking like a collection of very small dots. 

Common types of mold

According to the EPA, mold can grow anywhere, as long as moisture and oxygen are present. Some of the most common types of household mold include: 

Four 3-day old Aspergillus colonies on a Petri dish” by Adrian J. Hunter is licensed under CC BY-SA 3.0.

Aspergillus

This common type of indoor mold is especially prevalent after flooding or heavy water damage. It is also found around HVAC systems, on damp walls and wallpaper, and on flooring and carpets. It may be gray, green, or black, often fuzzy looking or with a speckled appearance. Though generally harmless, it may exacerbate allergy and asthma symptoms.

Alternaria brassicicola culture plate” by Seemadua, S. Department of Agriculture, Thailand is licensed under CC BY 3.0.

Alternaria

Generally described as fuzzy or “hairy” looking and dark green in color, alternaria mold likes damp environments and may indicate water damage. It can range from green to black to brown in color and is often spotted in humid areas such as around sinks and showers. 

Cladosporium sphaerospermum colony” by Medmyco is licensed under CC BY-SA 4.0.

Cladosporium” by 10423 is licensed under CC BY 4.0.

Cladosporium

This type of mold has a suede-like appearance and is typically green, black, or brown. It is often found on damp carpets, upholstery, curtains, and other textiles. It grows in both warm and cold climates and is considered a highly common household mold. 

Penicillium digitatum” by Adam Kranz is marked with CC0 1.0.

Penicillium

Moldy bread? It’s probably penicillium. However, this type of allergenic mold (often white and/or light green or blue in color) can also be lurking anywhere moisture is present—especially if there has been water damage in the home. 

Chaetomium globosum” by Sigrid Jakob is licensed under CC BY 4.0.

Chaetomium

Homes that have experienced a significant amount of water damage (such as roof leaks or basement flooding) will typically have chaetomium growth. This type of mold is often identified by its stale, musty odor and can be found hiding under carpets, in wood and drywall, and on ceiling tiles. The color is usually gray, black, or brown.

Pleiospilos nelii (split rock): Fusarium sp.” by Plant pests and diseases is marked with CC0 1.0.

Fusarium longipes” by Jie-Hao Ou is licensed under CC BY 4.0.

Fusarium

Another type of mold commonly found in homes, fusarium spreads quickly and likes moist, humid areas such as basements and around humidifiers and air conditioners. It also thrives in plant soil, so keep an eye out if you have indoor plants. Colors can be wide ranging, from white and yellow to pink, purple, and black, with a velvet-like texture. 

Stachybotrys chartarum” by Christine Braaten is marked with CC0 1.0.

What about black mold? 

The term “black mold” gets a lot of press, but in most cases it is referring to toxic black mold, or a species known as Stachybotrys chartarum. Toxic compounds released by this type of mold can be harmful to both humans and animals, causing symptoms that range from allergic reactions to severe respiratory issues. 

However, Stachybotrys chartarum is not commonly found in residential homes, unless there is:

  • An ongoing (and untreated) moisture problem
  • Heavy water damage that has not been identified or fixed
  • Poor ventilation
  • Excessive humidity or condensation
  • A combination of any of these factors

For example, a home that was flooded and left to sit for several months is a prime candidate for toxic black mold growth. This type of mold will generally appear dark green or black, with a slimy texture. 

Bottom line: Mold species are vast and often difficult to identify. 

Regardless of what type of mold it may be, finding mold growth where you and your family live is never a good thing. Because certain types of mold can cause health problems, as well as damage your belongings and the structural integrity of your home, it is important to have the problem assessed quickly and by a certified mold remediation specialist

Call CT Mold Pros today at (203) 920-0265 for a free estimate or fill out this short form with your message to schedule an appointment with one of our trained and certified specialists.

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