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What does building mold look like? Here is an online reference photo library of various kinds and colors of mold as it is found growing in buildings. These photos of mold on indoor building surfaces 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. If you don't see information you want, ask us for it using the comments box at the end of this article.

See links at page left (below the green link) for our library of photographs of building mold, organized by color and general appearance. These indoor building mold growths and their photographs and other examples of materials sometimes mistaken for mold have been collected in the U.S., Spain, Mexico, and France. If you are looking for photographs of mold as seen through the microscope, go to MOLD by MICROSCOPE.

See MOLD GROWTH on SURFACES for an illustrated and extensive index of what mold genera/species are frequently found on various building surfaces and materials. And see FIND MOLD in BUILDINGS, HOW TO.

See Mold Related Illness: Index of Symptoms and finally, for an atlas of building molds and for more microphotographs of building mold samples observed in our laboratory, see Mold Atlas of Indoor Clinical Mold, Pathogens, Allergens & Other Indoor Particles. And MOLD BY MICROSCOPE shows what mold looks like under the microscope.

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Photographs to Help Identify Mold in Buildings -
What mold looks like in a home or other buildings

Identification Photographs of Black Mold in Buildings - what does black mold look like?

More Photos & Close ups of Black Mold on Building Surfaces

Our mold photo at above left shows black mold colonies growing among green mold colonies on a laundry room ceiling, covering both plastic ceiling tile material (around the plumbing pipes) and drywall. It is often the case that multiple mold genera/species may be growing in the same area, often on the same surface, and at times, on top of one another.

As we advised earlier, look closely when inspecting or collecting test samples of "toxic black mold" because often there are other molds, sometimes more harmful and more easily airborne mold species on the same surface, on the hidden side of the same surface of drywall, or nearby. In this building that was still wet at the time we took this photograph, the airborne level of Aspergillus sp. and Penicillium sp. (the green, gray, and light colored molds in the photo) was very high while the level of airborne Stachybotrys chartarum, Cladosporium sphaerospermum, and Nigrospora sp. (black molds found on these surfaces) was very low.

Our photo at above right shows black mold colonies as smaller "spots" growing on the painted surface of cloth covering asbestos pipe insulation.

Our black mold photos above show dense black fungal growth on drywall (black mold on Sheetrock™ type wall surfaces) in areas that have been very wet. The distinct top edge of mold growth may mark a flood water level or a discontinuity in the wall material, such as a tape joint in drywall that affected the moisture gradient in the wall and thus the mold growth pattern.

Close up Photographs of Black Mold on Building Surfaces

Here we begin to "zoom in for a closer look at dense black mold growth on indoor building surfaces in a wet basement. Notice that the mold growth on drywall and often on other surfaces includes a family of circular growth patterns (upper area of photo at above right) until the mold growth has expanded to form a solid black covering (left wall of photo at left and lower wall of black mold in photo at right).

Our photo at above left shows black mold colonies as individual rounded "rings" on the cavity side of drywall on a building crawl area wall. The black mold photo at right shows how dense black mold may be hidden from view behind wall baseboard trim (removed for this picture) in a building that has suffered wet floors.

Black mold growth on furniture is obvious in these two photographs, of a mold on a leatherette surface (left) and on an upholstered chair (right).

In our photo at above left we see black mold and other mold growths on the kraft paper facing of fiberglass building insulation. Our black mold photo at above right shows that mold colonies do not always grow in the neat round ring-like colonies shown in some our earlier photographs.

Here we start to zoom in our photographs of black mold on building surfaces to show what mold colonies look like on close inspection in-situ. At left is mold on water stained drywall in a basement utility area. At right are small mold colonies that have appeared on a kitchen ceiling in just a few days after a heating system leak led to high indoor moisture and humidity levels.

Much more closely we can examine an individual black mold colony on a painted drywall ceiling (above left). In the microscope at 1000x we can see individual spores of Stachybotrys chartarum - a well known black mold that is often found on indoor building surfaces.

Questions & Answers about what mold looks like in buildings

Question: Is this stuff on my ceiling mold?

I just moved into a rental trailer and it had a strong musty smell. I thought, maybe it hasn't been aired out. well, after two days of doors and windows open, it still smells. I found the brown discoloration on the ceiling in the kitchen cabinets. Is it mold? Thank you, - L.B.

Reply: maybe not, but those water stains mean there may be a significant risk of hidden mold indoors

Your photo shows some heavy staining on what looks like suspended ceiling tiles. The brown stains themselves may not be mold but rather brown materials carried by roof leaks into the ceiling structure. Older trailers and mobile homes often have leaky roofs.

It looks as if water has also run down the wall surface and quite likely the wall cavity of the home below those same stains.

In this case the stains you see might not be mold but they do indicate that there is a high risk of mold in this home. Here are spots where I'd suspect a more hidden but possibly larger problem reservoir of mold when we see leak stains like yours:

• The ceiling tiles may themselves be moldy on their upper or hidden surface, depending on what they are made-of. Even plastic-faced fiberglass suspended ceiling tiles that might not look moldy may in fact be contaminated if they have been wet. See INSULATION MOLD.
• The back side of wallpaper that has been soaked is often moldy. At Other Places to Look for Hidden Mold we include a photo of mold found behind wallpaper that looked just fine from the room side.
• If the walls are covered with drywall behind that wallpaper, its cavity side may be moldy, though more likely your walls are paneled. Un-painted cavity side of wood paneling often supports mold growth and of course insulation within the wall cavity may be wet and moldy too.
• Finally, where we see significant stains at a wall/ceiling juncture indicating a history of roof leaks that sent water into and down the wall, we take a close look at carpeting, carpet padding, and insulation that may be under the floor below.

I suggest having someone take a look at the insulation and floor condition in the area of leakage from below the mobile home. If that area is wet and damaged you can pretty much expect that there is hidden damage and mold in the ceiling and wall above.

If the damage is not so extensive that immediate major repairs to the structure are needed, but if there appears to be anything greater than 30 sq.ft. of moldy material, professional cleaning and repairs are needed. And the cleaning and repair work cannot be concluded before the leaks are fixed. Also see ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD.

Watch out: in some mobile homes where there has been chronic leakage we have seen floors that were badly deteriorated and even collapse.

Finally, because you are renting, you will want to see our mold advice for renters: RENTERS & TENANTS: MOLD ADVICE

Online Mold & Particle Identification Aids at InspectAPedia.com

• MOLD ATLAS & PARTICLES INDEX, Pathogens, Allergens and Other Indoor Particles - actual and possible medical health effects of Mold (separate online document)
• MOLD APPEARANCE - WHAT MOLD LOOKS LIKE Photos of what mold looks like in buildings, organized by mold color and appearance.
• 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, 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 APPEARANCE - STUFF THAT IS NOT MOLD Photos of material that is not mold but is sometimes mistaken for mold
• Recognize Harmless Black Mold Photos of of often recognizable, usually harmless or cosmetic black mold on wood
• MOLD BY MICROSCOPE Mold under the microscope - photo identification of the most common indoor molds found in buildings

Contact Us to suggest changes and additions to these online mold identification guides

Questions & Answers regarding this article

Questions & Answers about what mold looks like in buildings, including homes, offices, and even in boats, cars, trucks, and mobile homes.

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• Additional technical contributors & reference sources for this article are listed below.

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MOLD INFORMATION CENTER

MOLD APPEARANCE - WHAT MOLD LOOKS LIKE
  Black Mold  Brown Mold
  Green Mold  Red Mold
  Yellow Mold  White Mold
  Invisible Mold
  Meruliporia Mold Photographs
  Mildew Photographs
  Recognize Cosmetic Mold
  Recognize Harmless Black Mold
  MOLD GROWTH ON SURFACES, PHOTOS
  Stuff that is Mistaken for Mold

MOLD APPEARANCE - STUFF THAT IS NOT MOLD
  HARMLESS INDOOR PARTICLES
    BASKETBALL MOLD SYNDROME - BBMS
    Black stains from soot/thermal tracking
    Black stains from animals
    Black cosmetic mold
    Efflorescence & brown deposits
    Efflorescence & white or brown deposits
    House dust
    Pollen
    Sprayed foam insulation
    White stuff that is not mold
    Wood sap

• Thank you to reader Thomas M.Brooks for attentive editing assistance 03/30/09

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
• Environmental Health & Investigation Bibliography - our technical library on indoor air quality inspection, testing, laboratory procedures, forensic microscopy, etc.
• Adkins and Adkins Dictionary of Roman Religion discusses Robigus, the Roman god of crop protection and the legendary progenitor of wheat rust fungus.
• Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
• "A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
• US EPA - Mold Remediation in Schools and Commercial Building [ copy on file as /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
• US EPA - Una Breva Guia a Moho - Hongo [on file as /sickhouse/EPA_Moho_Guia_sp.pdf - - en Espanol

Mold Contamination Testing, Cleanup, Prevention: references & products

• The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems
• Aerobiology, Building Science, Microscopy, & Laboratory References, an extensive technical bibliography
• Allergens: what they look like in buildings
• Associations: Sick House, Sick Building, SBS - Air Quality, Government, Private Associations and Information Resources
• Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon)
• Atlas of Mold Related Illness: Index of Symptoms and health, physical, neurological, psychological, and other complaint which people suspect may be mold or building-related.
• Atlas of Indoor Mold, Online Clinical Mold Atlas, Toxins, Pathogens, Allergens and Other Indoor Particles - Medical Health Effects of Mold (separate online document)
• Black Mold that is Harmless Photos of recognizable, usually harmless black mold on wood, bluestain, ceratocystis, ophistoma
• Building Floods: quick steps after a building flood or plumbing leak can prevent costly mold contamination
• Classes of Mold: what types of cosmetic, allergenic, or toxic mold are a problem? Can mold be cleaned-up successfully?
• Clinical Mold References - Detailed bibliography of mold reference texts
• "A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
• "Disease Prevention Program for Certain Vegetable Crops," David B. Langston, Jr., Extension Plant Pathologist - Vegetables, University of Georgia (PDF document) original source: www.reeis.usda.gov/web/crisprojectpages/209797.html
• "Disease Prevention in Home Vegetable Gardens," Patricia Donald, Department of Plant Microbiology and Pathology, Lewis Jett
  Department of Horticulture, University of Missouri Extension - extension.missouri.edu/publications/DisplayPub.aspx?P=G6202
• "Management of Powdery Mildew, Leveillula taurica, in Greenhouse Peppers," Ministry of Agriculture and Lands, British Columbia - Original source: www.agf.gov.bc.ca/cropprot/peppermildew.htm
• Environmental Health & Investigation Bibliography - our own technical library on indoor air quality inspection, testing, laboratory procedures, forensic microscopy, etc.
• Fiberglass: Mold in Fiberglass Insulation© 2005 comments about a field study in process, & more about health hazards from fiberglass insulation - DJF
• Fifth Kingdom, Bryce Kendrick, ISBN13: 9781585100224, is available from the InspectAPedia online bookstore - we recommend the CD-ROM version of this book. This 3rd/edition is a compact but comprehensive encyclopedia of all things mycological. Every aspect of the fungi, from aflatoxin to zppspores, with an accessible blend of verve and wit. The 24 chapters are filled with up-to-date information of classification, yeast, lichens, spore dispersal, allergies, ecology, genetics, plant pathology, predatory fungi, biological control, mutualistic symbioses with animals and plants, fungi as food, food spoilage and mycotoxins.
• Fungi, Identifying Filamentous, A Clinical Laboratory Handbook, Guy St-Germain, Richard Summerbell, Star Publishing, 1996, ISBN 0-89863-177-7 (English) (buy at Amazon)
• Looking for Mold Procedure: what mold is often found where in buildings - simple technical presentation
• Meruliporia: the house eating fungus or "poria"
• Mold Action Guide: Step-by-Step Instructions, What to do about mold, mildew, and other indoor allergens
• MOLD APPEARANCE - WHAT MOLD LOOKS LIKE Photos of what mold looks like in buildings
• MOLD APPEARANCE - STUFF THAT IS NOT MOLD Photos of NOT-mold material that is sometimes mistaken for mold
• MOLD ATLAS & PARTICLES INDEX, Pathogens, Allergens and Other Indoor Particles - Medical Health Effects of Mold (separate online document)
• MOLD BY MICROSCOPE Mold under the microscope - photo identification of the most common indoor molds found in buildings
• Mold FAQs Answers to Most Questions about Indoor Mold, Mold Related Illness, Mold Cleanup, Mold Prevention
• US EPA: Mold Remediation in Schools and Commercial Building [ copy on file as /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
• Mold spores in the Home - a Photo ID Library for detection and identification of mold allergens
• Mold Test Kits - How to Collect and Send Your Own Mold Sample to our mold testing lab or to any mold lab you wish
• Most Common Indoor Molds Found in Buildings, A Table of
• Mycology, Fundamentals of Diagnostic, Fran Fisher, Norma B. Cook, W.B. Saunders Co. 1998, ISBN 0-7216-5006-6 (buy this book at Amazon)
• Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous.
• Rot concerns in buildings-some building mold such as Meruliporia incrassata "Poria" risks serious rot and hidden structural damage
• US EPA: Una Breva Guia a Moho - Hongo [on file as /sickhouse/EPA_Moho_Guia_sp.pdf - - en Espanol