Types of Mold in Homes that You've Probably Seen

13 Types of Mold in Homes that You Probably Unaware Of

Have you ever seen a blue color mold? What about Stachybotrys chartarum is the scientific name for black mold? Which type of mold can grow in warm and cold condition? There is so much more than is to mold that you are probably unaware of and we are here to reveal it all. Some of the facts below might be particularly useful to you while others is an interesting point or even bizarre to begin with. In this compilation post, we will explore the different types of in-home mold ranging from popular to the rarely sighted one, health risks, where to spot them and ways to deal with it.

Short answer

Alternaria, Aspergillus, Cladosporium, Penicillium, Stachybotrys, Acremonium, Aureobasidium, Chaetomium, Fusarium, Mucor, Trichoderma, Ulocladium, Serpula Lacrymans.

Long answer

Mold is a tough organism that can survive in both indoor and outdoor environment. With at least 100,000 different types of species, mold comes in different sizes, shapes, and colors. There is also good, beneficial mold use in medicine, food (cheese in particular) and plain stinky mold that brings nothing but bad health when we inhaled. The top 5 most common types of molds in home include Alternaria, Aspergillus, Cladosporium, Penicillium and the notoriously toxic Stachybotrys (black mold). Other types of mold that you would find in homes include Acremonium, Aureobasidium, Chaetomium, Fusarium, Mucor, Penicillin, Trichoderma, Ulocladium and Serpula Lacrymans. While there are many mold testing kit available online, dealing with indoor molds is generally the same and should be done at the quickest possible time.

Most Common Types of Mold in Homes

Image by Wikipedia


  • Rarity  (Very common)
  • Typically found – Shower, bathtub, sink, leaky pipes, plant soil, wet object
  • Health risks – Allergic reaction, hay fever, respiratory infection
  • Harmful level  (Low – Hazard Class B)

Arguably the most common bathroom mold types, Alternaria is often seen in bathroom/ washroom objects like sink, leaking pipes, shower, bathtub due to the high dampness level. It can also grow on wet objects like carpet, boots, ventilation or windows frame if is not dry up properly. Most species of Alternaria has an ovoid tapering, club shaped that is only viewable under a microscope. You can identify the mold with its gray-green and close to black color patch.

Alternaria is not very harmful compared with black mold but can cause irritation if is not handle with care. When we inhaled Alternaria mold into our body, the fungus will be deposit inside our nose, mouth or upper respiratory tract which can cause allergic reactions like cough, sneezing, running nose to the more severe asthma, hay fever. People with immunocompromised (impaired immune system) like AIDS patients are also more prone to the allergenic mold. Scrubbing with few drops of essential oil can easily remove Alternaria on non-porous surface.

Image by Aspergillus Web


  • Rarity (Very common)
  • Typically found – House dust, air conditioning, heating ducts, insulation, bathroom, basement, food
  • Health risks – Respiratory infection, aspergillosis, allergic reaction
  • Harmful level  (Medium – Hazard Class A)

Aspergillus is a tough allergnic mold that can survive on both outdoor (decaying leaves, compost piles and house dust) and indoor (air condition, heating ducts, insulation, food). There are around 200 species of Aspergillus and only 40 of them are known to be harmful to human. Depending on the species type, Aspergillus shape and color varies from spore, flask, dome structure to yellow-green, purple-olive or even grayish-blue. Aspergillus niger, Aspergillus terreus, Aspergillus flavus is 3 of the more common species of the genus Aspergillus.

Removable with vinegar or baking soda, Aspergillus is not particularly harmful and rarely cause any infections to those with a strong immune system. For those with a weakened immune system like infant or asthmatic person, Aspergillus can trigger an asthma attack, cause Sinusitis and other respiratory problems like Pulmonary edema, Hypersensitivity Pneumonitis, and the infamous cancer linked Aspergillosis. Aspergillosis is a type of potentially fatal fungal infection that grows inside the lungs and can spread across the brain, heart or kidneys via bloodstream.



  • Rarity (Very common)
  • Typically found – Fabric, upholstery, carpet, cupboard, cabinet, floorboard, bathroom
  • Health risks – Skin allergies, eczema, respiratory infection
  • Harmful level  (Low – Hazard Class B)

Like Alternaria, Cladosporium is also a common outdoor mold that is often found in fall leaves or dead herbaceous. The airborne fungus can travel and grows inside your home through HVAC system or open windows. One of the larger genus of fungi, most Cladosporium species has a ellipsoidal to cylindrical shield-like shape and pigmented color from pale olive-green yellow to light brown. Another unique characteristic of Cladosporium is the allergenic mold can thrive in both warm and cold conditions, making it perfect for places like sofa upholstery, fabric, carpet and wood based furniture e.g. cupboard, cabinet, floorboard.

Most species of Cladosporium mold has little health risks to human. Exposing and breathing into Cladosporium will likely cause itchiness and skin allergies like rashness, dermatitis and skin inflammation. In very rare cases or people with weakened immune system, Cladosporium can cause typical respiratory problems like asthma, sinusitis and lung inflammation. Regularly clean HVAC system, aircon, and keep windows shut is the best way of reducing Cladosporium in your home.



  • Rarity (Very common)
  • Typically found – High dampness area including food, wallpaper, insulation
  • Health risks – Respiratory infection, allergic reaction
  • Harmful level  (Low to high Hazard Class B)

Penicillium is one of the easier mold to spot due to its association with damp environment. Often grows together with other types of mold, Penicillium is frequently seen in wallpaper, duct insulation, upholstery and household object like carpet, fruit, adhesive. Under microscopic view, you can see Penicillium has a spore shape with brush-like top where most species carrying a greenish, bluish or somewhat yellowish color. Fun fact about Penicillium: Penicillium chrysogenum fungus extract is used to made antibiotic penicillin while Penicillium is also used to create blue cheese.

Penicillin is not particularly dangerous to your health as only a handful of toxigenic mold species carry mycotoxins toxic substances. The risk of breathing to Penicillin is much higher compared with others as the spores can easily become airborne. If you are an asthmatic person, infant or elderly, do look out for this allergenic mold as long exposure can trigger asthma, sinusitis, hay fever to the more severe Pulmonary edema. We recommend getting an air purifier with HEPA filter to target airborne Penicillin before it lay its ground.

Stachybotrys Chartarum (Black Mold)
Image by Kristopha Hohn

Stachybotrys Chartarum (Black Mold)

  • Rarity (Common)
  • Typically found – High dampness area including wall, ceiling, wood, basement
  • Health risks – Respiratory infection, allergic reaction, skin allergies, vision impair, physical and mental problems, reproductive system troubles, circulatory and neurological problems
  • Harmful level  (High – Hazard Class A)

Stachybotrys AKA black mold/ toxic mold, is the most notorious types of mold found in home largely for its mycotoxins toxic substances. This slimy, greenish-black mold is considerably common and can be easily spotted in basement, wall, ceiling, piping area or underneath a sink where there is excessive moisture. Fortunately, Stachybotrys does not appear as frequent as above allergens because it requires a very high humidity level for growth. The most common species from its genus is Stachybotrys chartarum or Stachybotrys atra, Stachybotrys alternans, Stilbospora chartarum.

Stachybotrys can be extremely harmful to our body and should be dealt with immediately. In short exposure, you might experience symptoms like stuffy nose, cough, watery eyes, skin rash or headache. In long-run, exposing to black mold could lead to health risks like memory loss, depression, chronic cough and sneeze, abdominal/ joint pain, eyesight damage, hearing loss, irregular heartbeat, weaker immune system, lung inflammation, liver damage, infertility, and worst scenario death. Simple actions like fixing a leaky pipe or installing a dehumidifier does the trick. Hire mold remediator if the mold situation is getting out of hand.



  • Rarity (Common)
  • Typically found – Drywall, insulation, draining pipes, HVAC system
  • Health risks – Respiratory infection, allergic reaction, skin allergies, vision impair, physical and mental problems, reproductive system troubles, circulatory and neurological problems
  • Harmful level  (High)

Like Stachybotrys, Acremonium is a toxigenic mold which means it produces toxic substances. An evolving mold that evolves from small moist to powdery texture, Acremonium is either colorless or light in gray, pink or whitish color. Often found in hard to locate places like drywall, insulation, air conditioning pipes or HVAC system, it’s hard to identify Acremonium due to its small size and can grow alongside other types of mold. It does have a strong odor characteristic that is not on most mold. Despite consisting close to 100 different species, Acremonium mold is even more uncommon than Stachybotrys.

What makes Acremonium very harmful is the release of mycotoxins toxic. A carcinogen substance capable of causing cancer in living tissue. The toxic will also cause many other side effects similar to black mold like poor memory, insomnia, sinusitis, chronic cough, migraine, body pain, bone marrow, autoimmune disease, pulmonary edema, abnormal liver, neurological damage, impotence and ultimately death.


Aureobasidium (Pink Mold)

  • Rarity (Common)
  • Typically found – Behind wallpaper, wall paint, wooden surface, windows frame
  • Health risks – Skin allergies, allergic reaction, eyes infection
  • Harmful level  (Low – Hazard Class B)

Aureobasidium is a common, indoor allergenic mold that often mistaken as Stachybotrys because of it will eventually turn into slimy dark brown, black color. Unlike the black mold, Aureobasidium is less hazardous and started as creamy, pink color before changing into darkish color. Thrive on wet and damp places, you will typically find Aureobasidium behind wallpaper, wall paint or underneath wooden furniture. Aureobasidium pullulans are the most known type within its approximately 14 genus species.

Aureobasidium poses very little threat to humans but you should never have direct contact with the mold without wearing a mask or gloves. Exposing to Aureobasidium will lead to many allergic reactions but mainly to skin or eyes. Some people might experience unbearable itchiness while others might suffer from red eyes or skin rashness i.e. Dermatitis. Hire cleaning professionals if you are unsure if the mold is indeed Aureobasidium.

Image by Wikipedia


  • Rarity (Common)
  • Typically found – High dampness area including wall, wood items, cupboard, basement, food
  • Health risks – Skin allergies, allergic reaction
  • Harmful level  (Low – Hazard Class C)

A notorious and common indoor mold that is known for its ability to destroy items, Chaetomium is actually more damaging to household materials than causing infection to humans. Its perithecia (flask shaped) body might be only viewable through a microscope, Chaetomium strong musky odor will definitely alert you of its presence. Typically found in water-damaged materials from flood, leakage, Chaetomium grows rapidly in drywall, wallpaper, plywood, basement, and even food. Fortunately for us, Chaetomium is one of few molds that require chronic moisture conditions to grow. If you see a patch of mold that smells and change its color from whitish gray to brown-black overtime, it’s time to take action.

Chaetomium pose little health risk if is in low concentration level and airborne form. In some cases, exposure to Chaetomium could cause skin rash, watery eyes or itchiness that will eventually go away once you solve your indoor moisture issue. The first place to go is to check HVAC system or piping on any leakage. Tedious job and you should take extra caution like wearing mask and glove when dealing with mold contamination.

Image by AgriLife


  • Rarity (Common)
  • Typically found – Soil, plant, wallpaper, drywall, carpet, upholstery, wood flooring
  • Health risks – Skin allergies, allergic reaction, nail infection
  • Harmful level  (Low to high – Hazard Class A)

Fusarium is a ubiquitous species that can be allergenic or toxigenic mold. You will often find Fusarium airborne in soil, plants, wallpaper, drywall, upholstery, wood cabinet. You can differentiate Fusarium from other mold through naked eyes by its unique pinkish/ red, and white patchy colors. Like Cladosporium, Fusarium can survive and even grow on cold temperature. Children, asthmatic person or recovering patient are advised to stay far away from the mold.

Incomparable to the danger black mold brings, most Fusarium species post little harm other than allergic reactions to human. Expect rashness on skin, running nose, cough to bloodshot eyes. The few toxigenic species of Fusarium that are harmful to human body can lead to many respiratory health risks like Pulmonary edema, Hypersensitivity Pneumonitis, and Hemorrhage. Discard food, objects that are heavily infested with Fusarium is the quickest and best course of action.

Image by WiseGEEK


  • Rarity (Common)
  • Typically found – Soil, plant, HVAC systems, air conditioning, carpet, decaying food
  • Health risks – Allergic reaction, mucormycosis
  • Harmful level  (Low to high – Hazard Class A)

Just like Fusarium, Mucor is commonly found on soil, plant, decaying leaves but will also flow into our home in high condensation places e.g. air conditioning vent or HVAC systems. It’s hard to separate Mucor from other types of mold even though on zoom, it has a white grayish color and apical shape with soft fluffy texture. Mucor is known for its fast-growing pace which can be nasty if you have unattended leakage or dampness issue. Hire plumbers or get a dehumidifier A.S.A.P when you spotted Mucor mold in patches.

With around 50 types of species, most Mucor post little threat other than allergenic reactions like cough, postnasal drip, rash skin or headache. On rare cases or people will weaken immune system, Mucor can lead to serious infection call Mucormycosis, a fungal disease that can spread across you whole body through inhaling or skin cuts. Depending on types of Mucormycosis you being infected, Cutaneous Mucormycosis can cause skin inflammation, Rhinocerebral Mucormycosis can cause eyes, nose or brain damage, Renal Mucormycosis can cause kidney failure, Gastrointestinal Mucormycosis can cause abdominal pain, Pulmonary Mucormycosis can cause lung infection and Disseminated Mucormycosis is arguably the most serious of them all as the fungal spread through the entire body, causing fever, mental disorder and life-threatening situation.

Image by Reddit


  • Rarity (Common)
  • Typically found – High dampness area including wall, gypsum board, wood products, carpet
  • Health risks – Allergic reaction, respiratory infection
  • Harmful level  (Low to high)

A very common outdoor mold and equally common in-home mold, Trichoderma is a non-pathogenic mold that can be seen in green color patches along with other types of mold. Also known for its wood eating and anti-fungal ability where residue Trichoderma would protect plant/ crops from other fungal diseases. Like Penicillium, you will often find Trichoderma in wet and damp area e.g. wall, gypsum board, HVAC system, carpet and other wooden items.

There are 5 types of Trichoderma genus (Pachybasium, Longibrachiatum, Trichoderma Saturnisporum, Hypocreanum) and approximately 89 recognized species. Most Trichoderma mold is not harmful other than causing allergic reactions like skin rash, red eyes, and sinus. If you are unlucky enough to encounter Trichoderma aggressivum/ harzianum species, take extra caution as the mycotoxins toxic is equally as devastating as black mold. Health hazard includes heart inflammation, pulmonary edema to abnormal liver. Any natural remedies like Tea Tree Oil, Grapefruit Seed Extract, baking soda can effectively wipe out surface mold.

Image by assuredbio


  • Rarity (Common)
  • Typically found – Water-damaged items including gypsum board, wallpaper, wood material, tapestries, other upholstery
  • Health risks – Allergic reaction, skin allergies, hay fever
  • Harmful level  (Low – Hazard Class C)

Ulocladium is also a ubiquitous, common in house mold that often grows together with other molds such as Chaetomium, Fusarium, and Stachybotrys. Other than its dark grayish, black color and medium to fast growth rate, Ulocladium has a very high water requirement than other strains of molds therefore, it usually thrive after a flood where many household items would receive a sustainable amount of water damage. You will typically find the fungus in gypsum board, wall, basement, wood furniture, upholstery or even stationary items like paper.

Approximately 20 species of reported, Ulocladium might not have the devastation power of a black mold, it still can trigger symptoms from the standard cough, running nose to the more severe asthma and hay fever. People with impaired immune system e.g. children, post-surgery or HIV/ AIDS stand higher risk on subcutaneous tissue infections. Upon spotted the mold patches, remove it with a mixture of water and Hydrogen peroxide.

Serpula lacrymans
Image by constantinedd

Serpula lacrymans

  • Rarity (Uncommon)
  • Typically found – Water-damaged items including gypsum board, floorboard, wallpaper, wood material, tapestries, upholstery
  • Health risks – Allergic reaction
  • Harmful level  (Low)

Serpula lacrymans aka building cancer is the least common in-home mold you would encounter. It is notoriously famous for its building destructiveness than its toxicity to human. It can significantly damage wood items known as dry rot (wood decay) to the extent of masonry materials. When you spotted the distinguish red, brown, gray or black patches of mold, very likely the damage is made and it is irreversible.

Serpula lacrymans post little health risks to human and is typically link to allergic reactions like nasal congestion, cough, skin rash or aggravate asthma. Like other strain of molds, children, elderly and sick person stand a higher risk of other mold-related illness. Mold contaminated gypsum board, floorboard or wall paint that is unrepairable should be replaced immediately before the fungal start spreading. Hire a renovator, carpenter to remove and replace damaged part.

Other Mold Types That Can Be Found in Homes


3 Hazard Classes of Indoor Mold

In general, indoor mold is categorized into 3 different classes based on the health risk factor. Hazard Class A is the most dangerous that will have a direct impact on our health, follow by Hazard Class B, and Hazard Class C that has a lesser impact on our health. Below are some examples of indoor fungi associated with the group.

  • Hazard Class A – Stachybotrys, Aspergillus, Fusarium, Aspergillus, Geotrichum.
  • Hazard Class B – Aureobasidium, Penicillium, Alternaria, Cladosporium.
  • Hazard Class C – Chaetomium, Ulocladium, Wallemia.

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