Here we provide a table identifying the molds most commonly found on specific building surfaces or in/on building materials, furnishings, and other building contents.

Table of Common Indoor Molds Found on Building Surfaces

We list here the most common mold genera/species that our field investigations have detected in the screening of more than 3000 buildings between 1986 and the present.

Our page top photo of a mold damaged home shows an area with many different surfaces, materials, and in some cases different genera/species of mold contamination.

[Click to enlarge any image]

Like bird-watching, knowing what molds are likely to be present, what they look like, and what they like to eat, in other words, knowing some mycology, can make a significant difference in what a building inspection for mold actually turns up.

The difference between what molds are found in buildings and what molds commonly grow on various building surfaces is that most mold tests and mold reports involve samples collected by people who are not expert at recognizing and sampling mold in buildings.

So easy-to-see molds are over-reported and hard-to-see molds are under-reported in consumer-generated mold tests and samples. This reporting error also confounds attempts to correlate mold related illness and sick building complaints with specific genera or species of indoor mold.

Simple "mold screening methods" which omit the inspection, and "test only" sampling methods, such as air and culture methods can produce very unreliable results when used quantitatively - as we discuss
at IAQ Methods and at other articles at this website.

We are conducting ongoing research on the presence of specific molds on building surfaces and materials. Comments, critique, and contributions are invited. CONTACT US.

Wet or Moldy Furnishings:

following a building flood or water entry, some items that have been soaked do not need to be tested for mold contamination. A mattress that has been soaked (photo at left), had visible mold growth, or smells moldy is best just discarded. In our mold table below we include additional comments about furnishings that have may not have been wet but that may be mold-contaminated.

NOTICE: the molds we list as most-commonly found on building surfaces and materials in the table below are by no means the only genera/species that may appear in a specific build ling or case. Further, the mold genera/species that grows on a particular surface depends primarily on its growth conditions, in particular moisture level, and of course temperature, light exposure, and similar factors.

It is often the case that multiple mold genera/species are present on the same surface; some molds may be growing parasitically on others, and the particular mold found at a particular spot on a building surface may depend on the moisture level at that location.

Our investigations include extreme-mold cases in which a building had been subjected to severe water damage and left unattended for weeks or months, leading to extensive mold growth throughout the structure on many or nearly all surfaces.

In those extremely-moldy buildings we collected tape samples of mold on each different type of surface or material in the building as well as collecting vacuum and air samples of mold to observe the dominant airborne molds in those environments.

Our OPINION is that the genera of Aspergillus ranks as a wide-lead first as most widely adapted to grow on the greatest number of different indoor building surfaces, with Penicillium sp. probably second.

As we discuss
at MOLD FREQUENCY in BUILDINGS, these two mold genera are probably under-reported by consumers who collect mold samples using test kits as well as many mold test consultants who naturally focus on the most visually obvious dark or "black" molds in buildings. Outdoors we most often find the king of molds, Cladosporium sp. on widespread building surfaces.

Notes to Table above

1. We have been using special methods to test fiberglass building insulation for Penicillium/Aspergillus sp. in areas where the insulation has been wet or where insulation has been exposed to active mold growth such as over a wet crawl space or a moldy basement.

2. Some of the molds listed in this table, even though found indoors, are unlikely to be indicative of a growing mold reservoir of that genera/species. For example, we often find Cladosporium herbarium and certain Basidiomycetes such as Ganoderma sp./G. applanatum/G. tsuge in indoor air samples but we have not found these genera/species growing on building materials. Rather they enter in outdoor air.

3. In conclusion, this interesting table needs additional research with data provided by expert building investigators rather than self-collected data by individuals who spot first and sample first dark molds on building surfaces. Readers should

see HOW to LOOK FOR MOLD.

4. Sedlbauer, Klaus. PREDICTION OF MOULD FUNGUS FORMATION ON THE SURFACE OF AND INSIDE BUILDING COMPONENTS [PDF] Fraunhofer Institute for Building Physics (2001): 75-141.

 

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-06-22 by inspectapedia.com.moderator (mod) - look in the microscope for clues to IAQ & health hazards ... with care to get expert help!

@Anonymous,

So sorry but I really can't make out much from your photos. I think I see a dime for scale in some of your photos (cute);

I see what looks like a lot of fibres, one possible ascomycete (normal, harmless), and some dark objects that might be mite or other fecals.

You're right that various fibres are ubiquitous, and I'll add that in a typical surface sample or vacuum sample or "tweezed-out sample" one wouldn't expect them to be deposited homogeneously on a mattress or in other crevices on mattresses or furniture, carpets, etc.

There is not much chance that those fibres as I see them in your photos would explain occupant health complaints. Nor do they address a mold concern.

I must emphasize that while it's fun and interesting to look at stuff under the microscope, experts spend a lifetime in the lab and in formal training learning how to use the microscope, how to prepare slides, choice of mountants, refractive indexes, types of light, immersion oils, and an endless range of particle identification classes to become reasonably competent at particle and mold identification.

Even after nearly forty years of work in this field I don't consider myself anywhere near a top expert. Yet I have spent years in multiple classes at McCrone Research (forensic microscopy, particle identification), at the Harvard School of Public Health (mold & pollen identification), and at numerous clinics, summer spore-camps, and IAQ conferences and courses (field and lab methodology); usually most of the attendees were older than I (not any more as I'm old now) and some had already spent 40 years behind the microscope.

And many of my classmates knew ten to fifty times what I did. We try to pool our areas of expertise.

Really? So don't expect that even a smart and motivated homeowner or amateur with a microscope is going to quickly produce reliable results.

Watch out: also for a capture error: your attention may be so captured by one indoor health hazard theory that you fail to look more-broadly and may miss more-significant or more-urgent health or safety hazards.

Your doctor is wrong to look at you as if you're crazy, but quite right that it's not likely that what you're showing in these photos explains a health complaint.

Take a look at MOLD by MICROSCOPE https://inspectapedia.com/Microscopy/Mold_Spore_Photographs_by_Microscope.php

as that may give you a reference; most of those photos - at least mine - are shot at 300 x to 1200x in transmitted light, or polarized light, using various mounting liquids, chosen to suit the search target (mold vs pollen vs fibres etc) and sometimes having to vary the mountant refractive index as well.

You can collect surface or dust samples for a non-quantitative but in some regards more-reliable screen of mold-suspect materials that you find and can send them to any qualified mold or environmental test lab.

But instead of sending your mattress lint, consider these steps

1. Ask your doctor
   
   what environmental contaminants or IAQ hazards might cause or exacerbate your health complaints: which of those might be sought in your indoor environment to see if they are there at high levels
2. Hire an expert:
   
   if your doctor agrees that screening your home is worthwhile, then have an expert examine the whole building to identify the most-likely problem areas or sources or visible evidence of hazards bearing further investigation
   
   MOLD / ENVIRONMENTAL EXPERT, HIRE ? - for help in deciding if it's appropriate to bring in an expert.
   
   Watch out: don't hire someone who's just going to stop by and collect some samples to toss over the wall to a lab. It's the thorough inspection by an expert who knows what to look for that's more immediately needed than "testing"
   
   ACCURACY OF AIR TESTS for MOLD offers an explanation of why tests alone are not helpful
   

See also LAB PROCEDURES MICROSCOPE TECHNIQUES https://inspectapedia.com/Microscopy/Microscope_Techniques.php

and TAPE & BULK SAMPLING & TESTS for MOLD https://inspectapedia.com/mold/Mold_Test_Adhesive_Tape.php

On 2021-06-22 by Anonymous

@inspectapedia.com.moderator, @inspectapedia.com.moderator, Thanks so much for replying so quickly!!! You all (behind this website) are phenomenal!

I don't know enough to know which pictures are diagnostic, so I screen shotted a few and am uploading them as a jpeg. I hope that's okay! I have MANY more (and more detailed), but again, don't know enough to know which are even helpful to look at!

Thank you again!

On 2021-06-22 by Anonymous

Hello, and thank you SO much for all the careful work you're doing to provide us all with this critical info!! I'm wondering if you might be able to tell me if this looks at all like it could be mold/fungal and what kind of lab I should send it to in order to get tested? (I hope this is okay to ask--I don't mean to exploit your generosity here at all so pls tell me if I should ask elsewhere!).

I took pictures with 1000x magnification. It is debris I found in the creases of a mattress in our home. To the naked eye, there were two different kinds of substance-- one that was blue-ish and looked like lint and the other that was yellowish and looked grainy.

What's odd about this is that we only ever have had white sheets on the bed (which is very rarely used), and while I understand microfibers/plastics are all over now, I don't think that explains why they would be separated by color! That is what made me suspect it might be fungal. And under magnification, my (very uneducated) suspicions were heightened.

When I noticed it, I took a small sample and then I cleaned it up, enclosed the mattress in two allergen encasements (no idea if that did anything). When I sampled, I (stupidly) mixed the two different "kinds" I noticed in different places. We have far more generic looking mold elsewhere and are about to do a remediation (via a contracted professional) as we are all showing signs of significant mold illness.

I am also dealing with a **potential** dermatological fungal infection and so naturally, when I saw this debris (located on the mattress in the room where I work all day long), I wondered if this might be a culprit. I've shown pics to doctors who looked at me as if I was crazy for suggesting this might be a part of the problem.

I'd like to send the debris for proper testing, but I don't even know how to classify it so am not sure where or how to get it tested. I'm about to submit an EMRI test and the lab (Envirobiomics) generously said they could try, but I don't even know if this could be mold.

Any direction you can provide would be SUPER appreciated!! Thanks so much again for all your work (and so sorry for lengthy comment!!)

On 2020-08-28 by Helen Martin

Yes, there is a need for additional research from our side as well. The presence of mould is a serious concern. I got to know this when I hired the home inspection company, and the building inspector from Perth told me that protection of mould is only possible through its detection.

Following are some useful detection ways:

• Be aware of water leaks
• Periodical Testing of the home plumbing system
• Get a mould inspection once in every year.

Thanks, hope all these are helpful for everyone.

On 2018-10-15 by (mod) - Is "Toxic black mold" worse than green or other colured moulds? - NO.

Matt

You ask a very important question that points to an area of much misunderstanding.

Is "Toxic black mold" worse than green or other colured moulds?

Some time ago a news article about a black mold contamination case involving Stachybotrys chartarum and serious illness led to a media focus on "toxic black mold" in articles that can be misleading.

It is not the case that "black mold" is necessarily more harmful nor more toxic than moulds of other colours.

In fact it is rarely the case that only one mold genera/species will be found in an area of mold contamination anyway. The conditions that make one mold grow will make several or more grow. However dark coloured moulds are easier to see than light coloured molds, so are often over-reported and over-tested while lighter coloured moulds are missed and under-tested and under-reported.

Nevertheless some of these lighter or green (or other coloured) moulds can be even more harmful than the most famous "toxic black mould" of S. chartarum I mentioned above.

For example Aspergillus sp. mold is very very common in buildings, more-common than Stachybotrys chartarum. Aspergillus sp. is often a green, blue, or gray mould but can be other colours as it is a large family or genera with many sub-species of various colours.

Let's compare a few features of Aspergillus sp. and Stachybotrys c.

Stachybotrys chartarum ( black mold) spores are large, black, and sticky. The mould evolved to be spread by sticking to cows' feet as cows trampled through mouldy straw. It can be highly toxic and produces toxic mold volatile organic compounds (MVOCs).

However because of its stickiness this mould is not easily made airbourne and becomes so only when violently disturbed, such as during demolition of moldy drywall.

And because of its large size this mould spore is not normally breathed deeply into the lungs. A doctor who specializes in mold-related illnesses told me that Stachybotrys-related mold illnesses manifest first in the upper airway - such as nose and sinus infections, while Aspergillus-related mold illnesses often manifest as lung infections - I'll explain further below. He noted that he could make a good guess about what sort of mold spore - by size at least - was the cause of a person's illness by the type of illness: sinus vs. lung, for example.

In comparison

Aspergillus sp. spores can be as small as 1 micron (1 / 50th the diameter of some human hairs) - less than 1 10th the size of an Stachybotrys spores.

These spores are easily made airbourne, are highly toxic, and worse, are breathed deeply into the lung (hence the very serious if not so common illness Aspergillosis).

Like bird-watching, if there are big black birds and small green birds, and if your "bird expert" is only looking for big black birds, she won't see and won't report those small, viscious, pecking little green birds.

But they're there.

To be fair to Aspergillus, it's a huge family. According to the US CDC,

Types of Aspergillus. There are approximately 180 species of Aspergillus, but fewer than 40 of them are known to cause infections in humans. Aspergillus fumigatus is the most common cause of human Aspergillus infections. Other common species include A. flavus, A. terreus, and A. niger. - source: U.S. CDC, retrieved 2018/10/15 original source: www.cdc.gov/fungal/diseases/aspergillosis/causes.html

which is ironic since the CDC source page is named for the causes of Aspergillosis - an Aspergillus infection of the lung not mentioned in their summary.

It is important to understand further that the very small size of those harmful Aspergillus spores means that they travel in air like a gas, riding gleefully and easily on air currents throughout a building, moving through tiny openings wherever air moves and ranging far afield.

Stachybotrys spores, big sticky fellows, are far less venturesome.

Finally about your photo:

Watch out: when you see very extensive visible mold such as in your photo that environment is absolutely unsafe, and the area should not be occupied nor even entered without wearing the appropriate protective clothing, respiratory, eye protection etc.
Professional cleaning involving inspection, definition of the extent of demolition and cleaning needed, and then removal of the mold and moldy materials, followed by more cleaning and by correction of the cause of the mold growth.

Thanks for asking. Let me know if you have more questions.

On 2018-10-15 by Matt

Why do some mould's appear green, wheras other mould's create a black toxic colour?

Is the black mould any more dangerous than the green mould?
IMAGE LOST by older version of Clark Van Oyen’s Comments Box code - now fixed. Please re-post the image if you can. Sorry. Mod.

On 2017-07-10 by Jimmy

@Kate C.,
My name is Jimmy Smith and I posted the question about the air handlers in our building.

On 2017-06-29 by Jimmy

The three air handlers where I work recently had fungal surface sampling done with the following results: (Unit 1) raw ct. 205 -540,000 spores/unit and 3+ growth, (Unit 2) 150 raw ct. 390,000 and 3+ growth and (Unit 3) raw ct. 65, 170,000 spores/unit count and 2+ growth. What does this mean to us who have been breathing this air for 10-15 years? Many of us have upper respiratory conditions....

On 2017-01-30 by Kate C.

May I know the exact date these informations are posted and who is the author.

On 2016-01-25 by Daniel

Hi, We are building a home and I think our OSB walls roof have aspergillus on them. It's probably 5-6 small areas the size of a dime. What's the best way to get rid of it? The roof is really tall, so I'm not sure how we are going to deal with that.

Question: mold on the basement floor

(Sept 15, 2012) Jay said:
White mold underneath boxes on basement floor - 2001 property, I assume there is no poly underneath the slab. Currently fixing it by sealing the floor with 3 coats of DryGard mildew resistant block sealer.

White mold underneath upstairs hypoallergenic carpet padding on 3\4" OSB sub floor which is sealed with oil based Kilz mildew blocker. ( sub floor had stains from previous owner )
The carpet pad is not able to breath. The padding is just like memory foam and contains a fiber 2x2mm meshing on the OSB side. This house stinks like minty mildew and has proper ventilation including ERV, HVAC and always under 50% RH. 39 to 45% usually.

Reply:

Jay, carpet on a basement floor over a slab is often a source of mold and other problems - I prefer not to use carpeting in such locations. I'd eliminate it entirely; Abd from the design you describe I'd check for a hidden mold reservoir on the underside of that OSB subfloor and any sleepers on which it rests.

The two approaches are: dry out the area by finding and fixing the source of water entry or dampness and use a design that does not invite mold growth by choice of different materials for floor covering.

You'd be better off with ceramic or vinyl tile on the concrete.

...

Continue reading at MOLD GROWTH ON SURFACES, PHOTOS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• ACCURACY OF AIR TESTS for MOLD
• BLACK MOLD, HARMLESS - Photos of of often recognizable, usually harmless or cosmetic black mold on wood
• LAB PROCEDURES MICROSCOPE TECHNIQUES
• MOLD / ENVIRONMENTAL EXPERT, HIRE ? for help in deciding if it's appropriate to bring in an expert
• MOLD APPEARANCE - WHAT MOLD LOOKS LIKE - Photos of what mold looks like in buildings, organized by mold color and appearance.
• MOLD APPEARANCE - STUFF THAT IS NOT MOLD - Photos of material that is not mold but is sometimes mistaken for mold
• MOLD ATLAS & PARTICLES INDEX, Pathogens, Allergens and Other Indoor Particles - actual and possible medical health effects of Mold (separate online document)
• MOLD FREQUENCY in BUILDINGS - Table of what mold genera/species are frequently found in indoor mold tests.
• MOLD GROWTH ON SURFACES, PHOTOS - Photos of what mold looks like in buildings on more than 100 surfaces, organized by mold growth on various kinds of building surfaces and contents or items found in buildings. Mold in situ.
• MOLD GROWTH on SURFACES, TABLE OF - Summary table of what mold genera/species are frequently found on various building surfaces and materials
• MOLD BY MICROSCOPE - Mold under the microscope - photo identification of the most common indoor molds found in buildings
• MOLD in the PETRI DISH, PHOTOS - what mold looks like on culture plates or in culture-type mold test kits
• MOLD RELATED ILLNESS SYMPTOMS - Mold Related Illness: Index of Symptoms. Readers should not rely on this document for medical diagnosis and instead should consult with their physician or with a specialist such as a medical toxicologist
• MOLD RESISTANT CONSTRUCTION - how well do different building materials resist mold growth?
• TAPE & BULK SAMPLING & TESTS for MOLD

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MOLD GROWTH on SURFACES, TABLE OF at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to MOLD CONTAMINATION & REMEDIATION

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