Photographs of mold growth in buildings:

Here is an extensive photo guide to fungi, mushrooms & mold growing on all kinds of surfaces of all kinds of materials found on or in buildings:

A photographic guide to the appearance of mold as it is found growing on more than 120 indoor building surfaces and materials such as building contents, furnishings, trim, walls, wood, and personal or even plastic items found in buildings. What genera & species of mold commonly grow on different building surfaces? Mold on artworks, paintings, cultural artifacts is included.

What does mold look like growing on various building & other material surfaces? Beginning here is an online reference photo library of various kinds of mold as it is found growing on a wide range of surfaces and materials found on or in buildings.

These photos of mold on indoor various materials or "mold growth substrates" may help you recognize mold in buildings, recognize probably-cosmetic mold, and recognize stuff that is not mold and does not need to be tested.

Q&A about Reader Photos of Suspected-Mold on Various Building Surfaces

These questions & answers about what mold looks like - in-situ photographs of all types of mold growths found in buildings - were posted originally at MOLD APPEARANCE on VARIOUS SURFACES - our index to photos of mold on various materials - be sure to check out those illustrations and guides to recognizing mold contamination.

[Click to enlarge any image]

On 2019-07-13 by (mod) - White stuff on fiberglass HVAC air duct liner - is this drywall dust, effloresence, or mold?

Morgan:

The white material on the fiberglass duct liner in your photo looks like mold to me by its growth pattern and supported by your case history.

See AIRBORNE PARTICLE & MOLD LEVELS in DUCTWORK

Why this isn't drywall dust:

White deposits, if they were alone with no other colors of apparent mold colonies, might also be suspected to be drywall dust from sanding dust that was sent through the duct system.

However if the material were white drywall dust you'd find it first and thickest at the air inlet or air return duct and on the blower fan blades in the air handler. Absent heavy white goop deposits in those locations and then finding such white deposits only downstream from those locations is a compelling argument against dyrwall dust even without further testing.

Why this isn't effloresence:

The white material will not be effloresence. Effloresence is a mineral salt left behind when water passes through and then evaporates from the surface of masonry materials like concrete, concrete block, brick, mortar, stone.

Details are at EFFLORESCENCE SALTS & WHITE DEPOSITS

On 2019-07-13 by Morgan - white deposits in ductwork

Hi - reading a lot on this website as we are renters in a 3-level (w/ HVAC unit in 4th level crawl space) townhome in NC. I independently hired an air duct cleaning service, since I noticed that we were still wiping dust off of surfaces following some drywall repair and I have bad allergies.

The cleaning never started though, since the guy went up to the unit, looked inside the plenum box and suspects there is mold/other growth that needs to be remediate before cleaning can be done.

Couple of things/prior events to keep in mind:

Approx 6 months ago: HVAC utility drain clogged and was running over for a few weeks. We only picked it up due to a leak down on the 1st floor that was coming through drywall.

Approx 3 months ago: ServPro brought in to remove damaged drywall and bring in dryer fans. Drywall was replaced and sanded and painted (hence the dust mentioned above).

Approx 1 month ago: noticed another leak on 1st floor. This one resulted in replacement of HVAC system (coils were dirty, lines freezing over thus causing leak).

This week: duct cleaning service came out but could not proceed further. HVAC company that installed new unit came out and looked at plenum box, saying it is probably efflorescence growing in the fiberglass box due to sediment from the water that runs through the unit. Unit is on 4th floor, in an unconditioned crawl space so during summer months it is hot and humid up there.

I welcome your thoughts on situation and whether you’d recommend a test for mold. Property manager is slow to act, and given I have allergies (esp to mold), I don’t want to just sit around and wait. Photos also attached.

Thanks!

On 2018-10-09 by (mod) -

There are some insects that make spotty deposits, including spider droppings. But if you magnify your spots and see what looks like fuzzy growth that's more-likely a fungus. Perhaps you can try taking a photo through a magnifying glass. The photos from you that I've seen so far are a bit blurry for me to be confident about what we have.

On 2018-10-09 by J

thanks so much! Will see if it comes back or reappears anywhere else. Any chance it’s related to insects?

On 2018-10-09 by (mod) -

Could be a fungus + indoor humidity or damp surfaces. I'd have to see a tape sample of the material to make a reliable identification - and would do so -pro-bono, but cant' as I am out of the lab on assignment for the month.

On 2018-10-09 by Anonymous

thanks! I had similar spots but darker and many fewer in a different area of the apartment a few weeks ago, but the distinct pattern is very strange.

IMAGE LOST by older version of Clark Van Oyen’s useful Comments code - now fixed. Please re-post the image if you can. Sorry. Mod.

On 2018-10-09 by (mod) - what are these small black spots

There are some insects that make spotty deposits, including spider droppings.

But if you magnify your spots and see what looks like fuzzy growth that's more-likely a fungus. Perhaps you can try taking a photo through a magnifying glass. The photos from you that I've seen so far are a bit blurry for me to be confident about what we have.

On 2018-10-09 by J

thanks so much! Will see if it comes back or reappears anywhere else. Any chance it’s related to insects?

On 2018-10-09 by (mod) -

Could be a fungus + indoor humidity or damp surfaces. I'd have to see a tape sample of the material to make a reliable identification - and would do so -pro-bono, but cant' as I am out of the lab on assignment for the month.

It's possible you are seeing not mold but thermal tracking on drywall nails - though usually you'd see more than just two such spots.

On 2018-10-09 by Anonymous

thanks! I had similar spots but darker and many fewer in a different area of the apartment a few weeks ago, but the distinct pattern is very strange.

On 2018-10-09 by (mod) -

I'm not sure, J. That could be a fungus, more-likely if the area was wet or, for example, was covered by a damp carpet or rug. If it recurs after having been cleaned-off with a household cleaner, I'd be surprised - let me know.

My guess, however is that we're seeing a deposit from someting wet placed on the floor.

On 2018-10-09 by J

Any idea what these spots are on wood floor in apartment? They appear to come off with water.

On 2018-08-08 by (mod) -

Rbow

Sorry but I can't say as I don't know what "this" is the subject of your photo of what appears to be a garage door and jamb and gasket and brick veneer on a building.

I suspect we're seeing either an algae or a mold.

On 2018-08-08 by Rbowman02 - black stuff on garage door jambs

What is this

On 2018-07-08 by Reese

I have been very sick and moody as well as had several odd symptoms since moving into my apartment can anyone tell me if this is toxic mold?

On 2017-10-31 by (mod) -

I can but guess that you'll want to clean that out, perhaps use a household cleaner to finish the job. Don't force muck down the drain as you risk clogging it.

On 2017-10-30 by Heather Weir

I have like black mud in my laundry tub

On 2017-02-21 by (mod) -

Could be a mold or a yeast - or insulation - or something else. If the total demolition is less than 30 sq.ft. it's not normally necessary to hire a professional mold remediator. Remove all drywall and insulation that was wet or looks moldy.

On 2017-02-21 by Sharon's

My microwave above my stove caught fire and I had to take it out the drywall behind the wall was crumpled and had tiny hairs growing out of it all of the pieces had little tiny hairs growing out of it what could that be

Reader Comments:

(Aug 3, 2011) taz said:
thank you for your help! i've been trying to find out if i have mold on my window in the bedroom and looks like i do. so thanks for the pictures it really helped me.

Question: tests for mold

(June 8, 2012) Anonymous said:
Is there any tests that can be done?

Reply:

Yes you can see articles above at CONTINUE READING that list mold test resources. First I suggest seeing MOLD TEST vs. PROBLEM DIAGNOSIS

There are various "tests" for mold, but used without a thorough inspection of the building inside and out, air tests and even surface tests can be quite unreliable.

Even when a test detects mold we can't know that the mold it detected is the mold that is a problem in the building unless the test was a surface sample that the investigator is confident accurately represents the dominant mold growth(s) in the building by area covered, location, etc.

And by that time, by eye, you already know that mold is present.

Indeed when a careful building inspection does not immediately find a significant visible mold reservoir, we might decide to examine settled dust as well as air (much less reliable) as an additional screening test.

Test results in that case are a helpful indicator that further inspection, perhaps using invasive methods such as making small test cut openings in most-suspect walls, ceilings, floors, could be in order.

Question:

(June 9, 2012) Manny said:

Can a humidifier cause mold growth in a building?

Reply:

Manny, mold is everywhere, always. High moisture conditions indoors are a gating factor in indoor mold contamination problems. So if the humidifier is not properly adjusted or is run to excess high indoor moisture would be the cause of indoor mold, not the humidifier itself.

Watch out: Failure to clean a humidifier can breed bacteria or other pathogens in the unit.

Question: black mold behind vinyl wall paper

(July 9, 2012) Lynz said:
Please help! :(
We are currently re-decorating my victorian end terrace house. The living room has dado rails and just above the rails we had powdery paint (?) settling on the dado. We brushed this off and applied a alkai-resistant primer ready to paint.

Can I just mention this was seen on the adjoining wall with next door, the external wall AND the internal archway to the dining room. When we tapped the plaster , parts sounded hallow , so then we hacked off the loose part and re-filled and plastered. This was all done weeks ago. This weekend weve started properly on the room and we took the dadorails off.

This pulled off part of the plaster on the external wall where the powdery area was a problem .

Under the rail is an obvious water mark and where the plaster has pulled off theres a green/black and rough white material. Now I know in the hallway the people before use have plastered OVER existing wallpaper. Im assuming this material in the livingroom is a kind of mold/fungus? Im scared to hack off the surrounding loose plaster because I know some species can be hazardous! Im totally at the end of my sanity with this house :( Any suggestions on what I can do myself? Or who is best to contact ?

(Aug 1, 2012) diane said:
I was exposed to a aspergillus mold in my classroom for which I became very ill. I have found blue black mold on the back of vinyl wallpaper backing up to a restroom. Any suggestions on the type or pictures of mold on vinyl wallpaper?

Reply: presence of "black mold" in a building should not be taken to be the most serious mold problem

Diane, "black mold" on the back of vinyl wallpaper could be any of many genera/species, and furthermore the presence of "black mold" in a building should not be taken to mean that the mold you see is the biggest or most serious mold problem present - it is just what you can easily see. The presence of visible mold means that conditions are ripe for mold growth indoors - which means that a competent check of the building for the presence and extent of mold problems may be appropriate.

And no, just telling me you see mold on wallpaper is not enough to offer a reliable identification of what genera/species is present. It's true that my study of what molds grow on what surfaces in buildings indicates that certain molds prefer certain growth substrates, but there are 1.5 million genera species to choose from overall, so to determine the identity of a mold we'd need to examine a sample under a microscope.

Question: musty odor in metal filing cabinets

(Aug 14, 2012) Linda said:
I recently bought used metal filing cabinets. Once home, I noticed that they have a musty odor.

It isn't noticeable unless I go very close to the inside of the cabinet drawers. These were from an architect and I believe were kept in a clean air conditioned office, but they are old so I don't know the history. What does the odor indicate? Could it be that they are just old? Have I brought something contagious into my home? Is there a way to get rid of the problem? I bought them to store artwork in, so I really don't want that odor to transfer. Thanks very much.

Reply:

Check the filing cabinets inside for signs of flooding; if the cabinets were insulated they may not be economically salvageable; if they are simple one-wall steel items they can be cleaned.

Question: Need to kill mold?

(Aug 19, 2012) ian watkins said:
we moved in to a bungalow six moths ago, every thing was bought,including the carpets. new, but we have just found the bedroom cupboards, cloths including shoes covered in a fluffy, raised and white mould/mildew,even under the carpet, the rest of the bungalow is unafected.

(Oct 13, 2012) Reyna said:
Hello, I am having a terrible allergic reaction to something and I'm not sure what, so I'm just trying to eliminate things

I built my own platform bed and when I took it apart the other day I noticed spots in the plywood where the layers had separated and there are dark spots in there.

I'm not sure if this would make sense, since I have my allergy attacks everywhere (work, friends' places) and not just in my bed, but I'm just wondering if these spots are normal. They don't look like mold, they're hard and I'm not even able to scrape them off with something.

Almost looks like the material tree bark is made of. I'm just confused. picture below:

(Oct 27, 2012) Gina Hansen said:

I have dark pumpkin colored growths on the outside of my refrigerator doors.

It is in the pattern of mold but I don't think it is mold. I have cleaned it with comet, Tilex, bleach and even tried polish remover. It never completely removes the growth but makes it so light it isn't that noticeable unless you really get up close and inspect it.

However, within a couple of days the dark growth is back and even looks worse. I can't get rid of it. Can anyone help me?! Please!!!

(Feb 7, 2014) gail mollin said:
How to kill mold on unfinished plywood in vanity under sink.
Had a water leak.

Reply:

search inspectapedia for

How to Clean Mold on Building Framing Lumber or Plywood Sheathing

to read our advice on this topic;

Basically, "killing" is not the best objective - as even dead spores can be harmful; you want to "remove" the mold by cleaning - any household cleaner is fine. If there are cosmetic objections to stains that remain (harmless) one can try cautious bleaching but otherwise it's the cleaning that is more important.

After the surface is cleaned, you can reduce the chances of new mold growth by using a sealant

Details are at MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD

Question: flooded basement, sewer backups, I'm worried.

(June 19, 2014) Danette said:
I have been renting a half house for 5 years now and have had water in the basement 3 times after the sewer pipe broke under the concrete floor in the basement. I just notices thes copper penny mushrooms growing all over the basement floor. Are they dangerous to our health? My landlord has not been over to do anything about them in 2 weeks now :( I am worried that they can cause my family and cats harm. Please any info?

Reply:

What you describe sounds like there could be serious bacterial hazards as well as mold contamination.

Detailed advice is at RENTERS & TENANTS ADVICE for UNSAFE or UNHEALTHY HOME

Question: hard brown foam like substance in the dog run

(Aug 1, 2014) Monica said:
I have been renting a house for 8 months and have just begun to notice a hard, brown foam-like substance that keeps appearing in the dog run.

At first, I thought it was foam insulation that was coming up to the surface, since it seems to only appear against the side of the house; but since it keeps appearing even though I dig them up and throw them away, I'm starting to think they might be some kind of fungi. The dog run consists only of dirt and gravel.

They are dark brown on the outside, but when broken open, they look like yellow insulation and are very light weight. Are these things harmful to my dogs and myself?

Reply:

Monica,
From just your text message I don't know what you are seeing at all. It might be a fungus or something else.

Question: mold on linoleum under the sink and at a toilet

(Nov 30, 2014) Michele said:
If I am seeing a darker color under my linoleum in the bathroom at the base of the toilet is that a sign that mold is under the linoleum? I also see the same darker coloration coming from under the linoleum that lines the bathroom sink.

Reply:

Michelle,

The dark colour could be mastic seeping upwards or stained sheet flooring from sewage water leaks OR it could be mold growing within the sheet flooring material. If wiping the surface is not fixing the trouble I suspect there is a leak or moisture problem to be found.

Question: black on styrofoam = mold?

(Jan 7, 2015) Diane said:
Why is everything that is plastic or Styrofoam is getting what looks to be black soot on them? Cups, trash bin. Some items are in the cabinets. I placed an envelope with a plastic address window on table and one day later is turning black

Reply:

Diane

We can hardly guess: there may be soil, dust, soot in the air in the area or something else. Use our CONTACT link to find our email and send me some sharp photos if you can - that may permit further comment.

Question: moldy rental property in Houghton MI

13 January 2015 Charlie said:
Hello,
Myself and three others live in a rental property in Houghton MI.

There are two area i am concerned about one is a leak that was comming through the ceiling in one room and im concerned there is mold on the ceiling and in the attic (this wasn't fixed since fall), as well as i came home from a month vacation and there are grey spots in the bathroom on the ceiling and walls when we use a ceiling fan wondering if you can tell me which type of mold they are. i will send you some pictures.

Reply:

You are welcome to send us photos for comment using the email found at our CONTACT link at page top or bottom. But one cannot speciate mold from an in-situ photograph. You may need to look further or even more invasively to find where there is actionable mold contamination - follow the water.

Also see RENTERS & TENANTS ADVICE for UNSAFE or UNHEALTHY HOME

...

Continue reading at MOLD APPEARANCE on VARIOUS SURFACES_GROUP_2 to continue reviewing our photographs of mold growth on all sorts of items, building surfaces, building contents, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Mold Identification Articles

• BLACK MOLD, HARMLESS
• MOLD APPEARANCE on VARIOUS SURFACES index to photos of mold on all kinds of surfaces and materials
• MOLD APPEARANCE - WHAT MOLD LOOKS LIKE - home
• MOLD APPEARANCE - STUFF THAT IS NOT MOLD
• MOLD ATLAS & PARTICLES INDEX
• MOLD FREQUENCY in BUILDINGS
• MOLD in BUILDINGS
• MOLD CONTAMINATION IN BUILDINGS - home
• MOLD by MICROSCOPE - mold under the microscope
• MOLD in the PETRI DISH, PHOTOS - mold on culture plates or in culture-type mold test kits
• MOLD RELATED ILLNESS SYMPTOMS

Suggested citation for this web page

MOLD APPEARANCE on VARIOUS SURFACES FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

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

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