How to Find Hidden Mold Reservoirs in the Home - a guide detection of mold allergens InspectAPedia® -
Where & How to Look When You Cannot Find the Mold Problem in a Building
How to Find & Test For "Invisible" Mold in buildings
Links to Photographs of black mold & other molds of various colors and textures in buildings
Photographs of mold on or behind wallpaper
Links to photos of stuff that is not mold or is harmless mold
Questions & answers about how to go about finding hidden mold contamination in buildings
How to find hidden mold contamination: What do we do when we cannot find a mold problem but we think there is problem mold in a building. Suppose an "air test" says there is problem mold indoors but you don't see where the "problem mold" is coming from? Where and How do we look for hidden mold?
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Results of a small test cut to check for hidden mold
Of course some important problematic mold reservoirs may be hidden inside building cavities where you won't see them without making a test cut in just the right place. We find these problems by inspecting "by context", that is, we decide where to make an invasive test cut by studying where leak or moisture problems have been or are likely to have been on a building.
This photo shows the hidden interior side of drywall on the test cut we made using the hole saw shown at the top of this page. The red material was a yeast which accompanied toxic mold which we confirmed was present in this wall cavity.
What's important is the development of a strategy for just where to make such test cuts to look for hidden mold. Random test cuts to screen a building for mold are unreliable.
Some other critical indoor mold problems may be on an exposed building surface or material, but the mold may be totally invisible to the naked eye. Such "hidden in plain sight mold" can be detected by a combination of common sense in recognizing mold-friendly materials and mold-producing conditions.
Exposed insulation may be mold contaminated
For example, fiberglass insulation in the ceiling over a flooded basement or crawl space is highly suspect. In some cases it's more economical and sensible to simply replace suspect material than to spend on testing it for mold contamination.
But where large areas or large expense would be involved, special testing methods can determine whether insulation or other mold reservoir materials are indeed mold-contaminated. We use a combination of vacuum pump and sampling cassettes to examine suspect building insulation.
Here is a photo taken in our laboratory when we examined our sample of insulation which we suspected would be mold-contaminated.
You can see extensive mold contamination of at least two types, Penicillium/Aspergillus spores and spore chains and darker fungal spores which are probably a species of Cladosporium sp. This insulation looked "clean" to the naked eye, but by context we suspected it would be a problem reservoir of mold.
Moldy fiberglass insulation is often missed by casual or inexperienced mold inspectors. The presence of spore chains confirms that we had active mold growth nearby if not in the insulation itself.
Making a larger wall test cut to check for hidden mold
Here we made a larger test cut in mold-suspect drywall because we saw a leak stain on the exposed surface. Even though there was no
mold on the exposed side of this wall, the water stain led us via this test cut to discover a leaky drain pipe that was previously unknown.
We would not make a cut like this unless there was external evidence of probable leakage into this cavity; a borescope might have found this problem too, though views through such instruments are quite limited and do not permit full examination of all materials and surfaces. Notice the evidence of mouse activity at the right end of this test cut?
Removing Wallpaper to Check for Hidden Mold
In our daughter's condominium we peeled down clean-looking wallpaper because we saw evidence of a history of leaks into the wall cavity at the window sill. Even though there was no
mold on the exposed side of this wallpaper, the water stains led us via this test to discover an area of Stachybotrys chartarum that was worth removing.
We often find mold growth behind wallpaper where there has been leakage or high moisture, including wallpapers used in bathrooms. Beware: some antique wallpapers which may be attacked by mold growth can cause the release of poisonous arsenic into the local environment.
Hidden Mold Under Furniture Drawers or Built-in Drawers
Simply pulling out a drawer may reveal problem mold growth. In this case we found this by pulling out the bottom draw of a built-in storage chest in a bathroom in an older home. we have also found Aspergillus sp. colonies growing on the un-finished underside of furniture and game tables.
Hidden Mold Behind Wall Paneling
We pulled down this bathroom paneling even though it's exposed side looked very clean, because other clues indicated that there had been a history of floor flooding in this area.
Hidden Black Toxic Mold Behind Drywall
We made the test cut you see in the photo at left above, even though the architect had directed the mold inspection and testing to be performed in a completely different building area.
That's because we saw water-damaged flooring and because occupants of this area were complaining of severe respiratory and eye irritation. We had to push insulation aside to show the black mold just visible in this photo on the cavity side of the opposing drywall. Our lab test indicated that we'd found Memnoniella echinata (a very close relative of Stachybotrys chartarum) which we find quite irritating.
The second photograph above shows how extensive the mold growth was when the lower wall cavity was cut away. This mold contamination had spread on 100 linear feet of wall in this area due to an air conditioning leak which drained into the channel formed by the steel u-channel used as a sill plate for this steel-stud wall.
Be sure to review our mold-detection guides & articles on where and how to look for hidden mold problems in buildings:
Questions & Answers regarding this article
Questions & answers about how to go about finding hidden mold contamination in buildings
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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.
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 at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
Allergies, Allergens, Allergy Testing in buildings - References & Products
Allergen Tests in buildings advice about how to test, what to look for, in evaluating the level of dog, cat, or other animal allergens in a building
"IgG Food Allergy Testing by ELISA/EIA, What do they really tell us?" Sheryl B. Miller, MT (ASCP), PhD, Clinical Laboratory Director, Bastyr University Natural Health Clinic - ELISA testing accuracy: Here is an example of Miller's critique of ELISA
http://www.betterhealthusa.com/public/282.cfm - Townsend Letter for Doctors and Patients
The critique included in that article raises compelling questions about IgG testing assays, which prompts our interest in actually screening for the presence of high levels of particles that could carry allergens - dog dander or cat dander in the case at hand.
http://www.tldp.com/issue/174/IgG%20Food%20Allergy.html contains similar criticism in another venue but interestingly by the same author, Sheryl Miller. Sheryl Miller, MT (ASCP), PhD, is an Immunologist and Associate Professor of Basic and Medical Sciences at Bastyr University in Bothell, Washington. She is also the Laboratory Director of the Bastyr Natural Health Clinic Laboratory.
Allergens: Testing for the level of exposure to animal allergens is discussed at http://www.animalhealthchannel.com/animalallergy/diagnosis.shtml (lab animal exposure study is interesting because it involves a higher exposure level in some cases
Allergens: WebMD discusses allergy tests for humans at webmd.com/allergies/allergy-tests
Animal Allergens: Dog, Cat, and Other Animal Dander - Cleanup & Prevention Information for Asthmatics and regarding Indoor Air Quality.
Recognizing Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
Rodent control issues, including dander, fecal, and urine contamination of buildings and Building insulation are discussed at our
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) - The Atlas of Clinical Fungi is also available on CD ROM
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?
"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
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.
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 [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
OTHER IAQ ISSUES: How To Find and Address Other Indoor Air or Indoor Environment Contaminants Besides Mold
Mold or allergens may not be the only or even the main indoor environmental contaminant. Don't let media attention to mold
cause so much enviro-scare fear that other, possibly more urgent hazards go un-addressed.
Ozone Warnings - Use of Ozone as a "mold"
remedy is ineffective and may be dangerous.
Pet control - if you can't say goodbye to your bird, cat, dog, guinea pig, hamster, tropical fish, then limit the
areas they occupy and limit the airflow from that area to sleeping or other areas of the building, use allergenic
bedding, eliminate wall-to-wall carpeting, improve housecleaning including use of a HEPA-rated vacuum cleaner. For more details
see our article Dog, Cat, and Other Animal Dander - Information for Asthmatics and Indoor Air Quality
Rodents, Mice, Squirrel Control - I find high levels of mouse and rodent dander, fecal dust, and urine-contaminated dust in some buildings,
and high levels of these materials in building insulation in those locations. If you have a mouse problem, particularly if mice and their waste (fecals or urine) are contaminating
the building HVAC or building insulation, may need both steps to clean up or remove infected materials and steps to stop an ongoing
rodent problem. If squirrels are a problem, the cleanup needs to include closing off entry openings into the building. Get some
help from a licensed pest control expert.
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