mold removal
12 Different Types of Mold in Homes

12 Different Types of Mold in Homes

May 8, 2024
Written By:
Uliana Miklyukh

Table of Content

Mold spores are all around us every day, in the air we breathe and even in the wind that blows into our interior spaces. In the natural world, mold spores play an important part in breaking down natural matter; however, when they get inside homes and form colonies, they not only look unsightly but also pose health risks.

Most people want to know what type of mold is dangerous in a house. The truth is that no human should be exposed to any type of mold for a long time and mold remediation should be done as soon as possible because, according to the U.S. Environmental Protection Agency, all types of mold cause potential health hazards. However, the chance of this fungus ending human life is incredibly rare under ordinary circumstances.

Apart from a step-by-step guide to how to get rid of mold found in the house, EuroMaids has compiled a basic guide to help you identify different types of mold. Pictures alongside the descriptions should help too, but when in doubt, call experts and order professional one-time cleaning or deep cleaning in Naperville, IL. Remember, you should never touch mold with your bare hands and always wear a mask and goggles during the removal process, as inhaled spores tend to thrive in human respiratory tracts.

Mold Categories

To start with, all mold is classified into three major categories, depending on the degree of harm it may cause:

  • Allergenic: These are harmless to your health and may cause mild allergies such as a blocked nose or skin irritation in those sensitive to mold.
  • Pathogenic: If you have a suppressed, underdeveloped, or compromised immune system, exposure to this mold can pose a significant health risk.
  • Toxigenic: This mold is incredibly toxic, and professionals should take prompt action to remove it.

The best way to prevent mold from forming is to periodically check areas in your home that produce microclimates conducive to mold growth and ensure there are no surfaces or areas that experience consistent dampness.

Here is a table giving you a preview of the mold types, their features, and health issues they may lead to:

Mold Type Description Health Concerns Common Locations
Acremonium White, pink, gray, or orange; moist, powdery texture Infections, bone marrow/immune system diseases, brain impairment, hay fever, asthma, hypersensitivity pneumonitis Drainpipes, window sealants, humidifiers, cooling coils
Alternaria Dark green or brown hairs, velvety texture Hay fever, asthma symptoms, hypersensitivity pneumonitis Carpets, wallpaper, textiles, window frames, HVAC systems
Aspergillus White, green, black, brown, or yellow; long flask-shaped spores Allergic reactions, asthma attacks, lung infections, respiratory inflammation Damp carpets, walls, doors, windows, pillows
Aureobasidium Pink, brown, or black; flat and smooth, becoming velvety Eye, skin, and nail infections Bathrooms, kitchens, tile grout, wallpaper, caulking, window frames, textiles, HVAC units, painted wood
Chaetomium Cotton-like texture, white to gray to brown to black Skin and nail infections Wallpaper, drywall, door/window trim, paper baseboards, cardboard, carpets, damp paper
Cladosporium Black, brown, olive green Allergic reactions (skin, eyes, nose, throat), rashes, lesions, asthma, lung infections, sinusitis Carpets, upholstery, fabrics, under-floorboards, cupboards
Fusarium Pink, white, or reddish-brown Nervous system damage, hemorrhages, internal bleeding Carpets, wallpaper, fabric, wood, upholstery, water-damaged surfaces, humidifiers
Mucor White, gray, or cream-beige; cottony texture Respiratory problems, allergic reactions, mucormycosis (fungal infection) Carpets, mattresses, upholstered furniture
Penicillium Blue-green or yellow Respiratory problems, sore throat (in some people) Fabrics, mattresses, couch cushions, carpets, plywood, insulation, damp building materials, books, boxes, wood
Stachybotrys (Black Mold) Black blotches or smears Nausea, vomiting, bleeding in lungs/nose Sweating pipes, under sink cabinets, washing machines, damp cars, roof leaks, windows with condensation
Trichoderma White or yellow, turning gray or dark Allergic reactions (asthma, coughing, lung infections) Water-saturated wood, gypsum board, paint, HVAC filters, mattresses
Ulocladium Brown, gray, or black Allergic reactions (asthma, hay fever, difficulty breathing) Water-damaged buildings, wet carpets, surfaces

Below, you can read about specific household mold types and see types of mold pictures.

1) Acremonium


Acremonium colonies are white, pink, gray, or orange. If found early, their powdery texture will be moist. Generally, this mold thrives indoors under very wet conditions following flood water damage and is commonly found in moist compact areas like drainpipes, window sealants, humidifiers, and cooling coils.

It’s one of the most dangerous house mold types. Its toxicity can cause infection in persons with wound injuries and lead to bone marrow and immune system diseases, as well as brain function impairment. More commonly, mold growth induces hay fever, asthma symptoms, and hypersensitivity pneumonitis.

2) Alternaria

Alternaria is one of the most common types of house mold, with over 250 species. Indoor Alternaria spores usually originate outdoors and multiply in carpets, wallpaper, textiles, window frames, and HVAC systems. Like all mold, it grows in damp and humid areas, reaching maturity in just five days. This type has a velvety texture with dark green or brown hairs.

Those with health problems such as pulmonary diseases, asthma, weak immune systems, and allergies are most vulnerable to this mold. Prolonged exposure to Alternaria has been linked to the onset of asthma in children, while allergies wrought on by its spores are more pronounced in spring and summer. This type of mold habitually lingers in the air on dry, windy days and, when inside, can grow under carpeting and inside walls in some cases.

3) Aspergillus


Aspergillus mold starts off white and transforms to green, black, brown, or yellow as it grows, depending on the species. It has long flask-shaped spores that can form thick layers or walls of mold. It is an allergenic mold, meaning it is most likely to produce allergic reactions such as asthma attacks, lung infections, and respiratory inflammation.

This mold species spreads rapidly in low-nutrient areas like damp carpets, walls, doors, windows, and even pillows. Aspergillus is one of the most common types of house mold found in homes around the world, along with the black and pink mold. It becomes dormant in colder areas but can survive and regrow in warmer weather.

4) Aureobasidium

This mold is common indoors in moist, damp, and humid areas like bathrooms, kitchens, tile grout, behind wallpaper, caulking, window frames, textiles, HVAC units, and on painted and untreated wood. Usually pink, brown, or black, Aureobasidium is flat and smooth and becomes velvety over time.

The primary health risk associated with this mold is its ability to cause eye, skin, and nail infections; it should never be touched with bare skin. Because it is not a primary human pathogen, not everyone exposed to it will get sick. Those at greater risk are people with compromised immune systems, babies, and the elderly.

5) Chaetomium


Chaetomium types of house mold can be found on wallpaper, drywall, door and window trim, paper baseboards, cardboard, carpets, and damp paper, making it a concern for libraries and book and paper archives. It has a cotton-like texture that changes from white to gray to brown and eventually black.

This allergenic and pathogenic mold mostly causes skin and nail infections. If you have Chaetomium in your home, you may have a serious mold problem, as its spores are larger and heavier than other types of mold. Chaetomium is a sign of constant moisture, so be sure to check any leaky water lines and roofs, and damp basements.

6) Cladosporium

Cladosporium is a mold genus with around 220 species, making it one of the more widespread types of house mold. Most of these allergenic mold colonies appear black, brown, and olive green and uniquely grow in both warm and cold conditions. Cladosporium thrives in carpets, upholstery, fabrics, under-the-floorboards, and inside cupboards.

Like Chaetomium, it causes allergic reactions to the skin, eyes, nose, and throat, with symptoms such as skin rashes and lesions, asthma, lung infections, and sinusitis. Even though it’s not deadly, it should never be handled directly without protective gear.

7) Fusarium


Once inside the home, Fusarium mold spreads rapidly from room to room. If you notice it in one area, it’s advisable to examine other areas in your home too. Usually pink, white or reddish-brown, this mold is toxigenic and allergenic, meaning that prolonged exposure may damage the nervous system and potentially lead to hemorrhages and internal bleeding.

This dangerous mold typically grows in carpets, wallpaper, fabric, wood, upholstery, and on any other surfaces that have suffered water damage. Because it requires wet conditions, it’s often found in indoor humidifiers and has a flat, wooly, or cotton-like texture.

8) Mucor

Similar to Fusarium, Mucor is a fast-growing mold that’s typically white, grey, or cream-beige, with a cottony texture. With over 50 species, this mold grows in thick patches or scattered colonies, feeds on house dust, and can live in carpets, mattresses, and upholstered furniture if moisture levels are high enough.

This strain can trigger respiratory problems and allergic reaction symptoms, including coughing, sneezing, a runny or blocked nose, postnasal drip, a sore throat, itchy eyes, sinus headaches, and skin rashes. In severe cases, it can cause mucormycosis – a fungal infection, which can damage and infect your eyes, nose, sinuses, lungs, and brain. Mucor is most commonly found in buildings that have suffered flood damage and remain damp.

9) Penicillium


The Penicillium genus contains over 300 species, including Penicillin known for important antibiotic production and food processing capabilities. Usually vivid blue-green or yellow, it does not typically produce serious toxins but remains a concern for immunocompromised individuals. Allergic reactions in the form of respiratory problems and sore throats may occur in some people.

Penicillium is one of the most common types of mold found in ordinary homes. It can grow on fabrics, old mattresses, couch cushions, carpets, plywood, and even in the insulation inside walls. Any damp building materials and books, boxes, or wood stored in moist basements are potential hazards.

10) Stachybotrys (Black Mold)

Characterized by black blotches or smears, Black Mold is unique because of its sticky spores that adhere to surfaces and can remain dormant for many years until reintroduced to a water source. While often touted as one of the most dangerous types of house mold, in most cases, it won’t affect or kill an individual.

However, prolonged exposure to Black Mold may lead to nausea, vomiting, and bleeding in the lungs and nose. This toxic mold favors humid microclimates produced by sweating pipes, underneath sink cabinets, in front-loading washing machines, damp cars, as well as nearby roof leaks and windows with condensation.

11) Trichoderma


Trichoderma is one of those bathroom mold types that start out as white or yellow and turn gray or dark as the colony matures. It is commonly found in water-saturated wood, gypsum board, paint, HVAC filters, and even in mattresses. Because this mold attacks wood, it can cause rot, damaging the structural integrity of your home, so proper mold removal is crucial.

People with allergies may experience severe reactions, ranging from asthma to persistent coughing and lung infections. If this mold contaminates an air conditioner, it poses a greater health risk, as it's extremely likely to spread all over the house, so be sure to check your HVAC system regularly.

12) Ulocladium

Ulocladium mold is brown, gray, or black and grows in water-damaged buildings, wet carpets, and surfaces. Unlike the other different types of house mold mentioned, it needs large amounts of water to survive, so if present, it’s a clear indication of severe water damage.

Textually it’s like cotton wool grows rapidly and takes around five days to attain maturity and produce spores. Once inhaled, it may cause allergic reactions like asthma, hay fever, and difficulty breathing. Ulocladium is often found alongside Chaetomium, Fusarium, and Stachybotrys, increasing its potency.



Growing in damp areas, household mold types can produce mycotoxins, resulting in mold allergies and other health problems. Yet, while mold is harmful to humans, it is only after prolonged mold exposure that severe health effects occur, and only in very rare cases is it fatal. It’s impossible to eradicate spores as they are part of the natural environment’s ecosystem. However, keeping your home, and especially the bathroom, clean and knowing how often you should clean your house, prevents colonies from forming.

Our professional team at EuroMaids will be happy to clean your space in Naperville, IL to ensure it stays mold-free. Our range of comprehensive cleaning services will make your space look as good as new! Call us at (630) 931-8480 or get your free quote today.

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