Mold on Dirt in Crawl Spaces, Basements, Floors

How to recognize and remove mold contamination from dirt or soil such as in crawl spaces or other dirt floors
Yellow mold in crawl spaces may be destructive Meruliporia fungus
White mold found on crawl space or basement dirt floor may be a basidiomycete.
Photographs of mold growing on dirt crawl space floors - soil fungi under or in buildings
References

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This article gives advice on how to find, identify, clean up or prevent mold growing on dirt or soil surfaces such as in building crawl spaces or in dirt floor basements.

Our photo (above) shows thick pale yellow fungal growth on dirt in a damp crawl area.

FIND MOLD in BUILDINGS, HOW TO describes how to find mold and test for mold in buildings, including how and where to collect mold samples using adhesive tape - an easy, inexpensive, low-tech but very effective mold testing method. (See TEST KITS for DUST, MOLD, PARTICLE TESTS for details). This procedure helps identify the presence of or locate the probable sources of mold reservoirs in buildings, and helps decide which of these need more invasive, exhaustive inspection and testing.

MOLD on DIRT FLOORS: Mold on Dirt in Basements & Crawl Spaces

Introducing Soil Fungi - "Dirt Mold"

A broad range of fungal species among at least seven genera may be found growing on or in soil [1] and because the interaction between soil and seed fungi has been studied widely in work on plant pathogens, they are studied worldwide.

However, texts that help identify soil fungi may be incomplete when it comes to mold on or in or beneath buildings. Building conditions that produce mold growth may generate fungi that vary from how they may appear in the lab in a culture plate, and building mold, even mold on dirt in a crawl space may appear different from the same genera/species growing in nature, say in the woods.

And because mycologists so often study fungi prepared from cultures, in my (DJF) experience, texts used as identification guides may present photographs of fungi that do not necessarily match what these same genera and species may look like when found in nature. Here we provide photographs of fungi (mold) growing on soil in or beneath buildings.

What is the Significance of Soil Fungi In a Building?

Photograph: fungus and mold growing on dirt at a crawl space concrete block wall - © Daniel Friedman

Our photo (left) shows a fungal fruiting body or mushroom growing out of a concrete block basement foundation wall. The yellow fungus growing on the mushroom may be a second opportunistic parasite.

Depending on genera/species a mold growing on dirt might be toxic, pathogenic, or allergenic, though in our experience (warning, we are not a mycologist).

Interestingly Watanabe reports that some of the mold genera commonly found as problematic mold reservoirs inside buildings or on building surfaces also include species found in soil, including two Stachybotrys species, S. corda and S. elegans, and a still longer list of Aspergillus species: including Aspergillus brevipes, Aspergillus fumigatus, Aspergillus niger, Aspergillus parasiticus, and others.

The growth of fungi on or in "dirt" below a building, say in a wet crawl space, should come as no surprise: soils both under buildings and in more natural settings (the woods) contain organic matter that contains nutrients inviting to molds.

Previously I had stated here that the chance that mold from crawl space dirt passes throughout a building as problem spores is lower than otherwise, principally because of the wet conditions in crawl spaces, but on learning that some easily airborne genera such as Aspergillus may be present, I have amended that position.

Mold on Crawl Space Dirt? Look Up!

More significantly, the conditions of moisture and presence of organic matter such as wood framing and also hospitable moisture holding materials such as fiberglass insulation [see INSULATION MOLD] all mean that where you see mold on dirt in a crawl space you should be looking "up" to inspect the building walls and floor structure overhead for other mold growth that could be a problem.

An inspection of wood framing and subfloor over a damp moldy dirt-crawl space or basement should be conducted using light and careful examination of the surfaces - see FIND MOLD in BUILDINGS, HOW TO and also USING LIGHT TO FIND MOLD - how to use light when looking for mold.

In any event, ne would want to be careful not to get mold in a cut, or in your eye, even if it does not appear to be an airborne species that can be easily inhaled.

Other Nutrients Encouraging Crawl Space Mold and Mold on Dirt

Mold might also be growing apparently on dirt but actually on something that spilled or was left atop the dirt - which could mean other fungal species than the soil fungi we just cited.

In any case if there is only a small amount of mold - a few square feet - it's reasonable for a homeowner to remove the visible mold and surface soil - just an inch or less. There may be fungal components deeper in the soil, but we're going to address that by drying out the area rather than digging up the whole house.

Our photo (left) of white-colored mold on dirt , was contributed by a client whose crawl space contained Meruliporia sp. fungus on the dirt (see below). We did not process a sample to identify this white fungus in the lab. It may be a different species from others in the crawl area, and its growth may have been related to items such as cardboard or wood left on the dirt floor, or due to a buried concrete block - notice the roughly rectangular pattern of the white mold growth at the center-right in the photo.

But before sampling what looks like "white mold" on dirt or on a masonry surface, take a look at Efflorescence & white or brown deposits - very often the white crystalline looking substance in these locations is not itself mold, though it is a moisture indicator, meaning mold may be nearby.

What to Do about Mold on Dirt Under a Building

Many readers have asked us what to do about mold found growing on crawl space dirt or on a dirt basement floor. I've often seen orange and yellow molds and yeasts growing on wet dirt in these areas.

If the area of mold on dirt is large, more than 30 sq.ft., and if it's not a harmless cosmetic mold, professional cleanup would be appropriate, but only after a competent and independent (independent from the cleaning company) inspection diagnosed the extent and cause of mold and thus provided you with a mold cleanup plan.

If you see a large area of moldy soil that appears homogenous in character (color, pattern, growth surface, etc) then it may be economical to collect a sample to send to an independent lab for identification (mine or any independent mold testing lab - we give instructions on how to collect mold samples at Mold Test Kit Procedures.)

Meruliporia fungus on dirt in a crawl area (C) Daniel Friedman

It's essential to also find and correct the cause of mold growth: Any mold cleanup anywhere in a building, whether its on crawlspace dirt or basement soils, must be followed by a diagnosis and correction of the moisture source that invited the mold growth, or the mold problem will simply recur.

The fungus in this photo mailed to us by a client was identified as Meruliporia incrassata - a mold that can attack wood structures causing significant damage.

We discuss this fungus at Meruliporia Mold Photographs. Although this recently-built home, located at 5500' in the Sierra Nevada mountains had crawl area ventilation, snow melt draining towards the structure caused chronic wet conditions and was surely a significant contributor to this mold growth.

Furthermore, and possibly more important, soil mold in a basement or crawl space is an indicator of wet conditions, which means that more-problematic molds may be growing on wood or paper or other organic surfaces nearby - and may be more of a problem for building occupants.

For example if insulation were installed in this crawl space ceiling it would be likely to have mold contamination, though more likely from Aspergillus sp. or Penicillium sp. - different fungal genera/species prefer to grow on different materials. See FIBERGLASS INSULATION MOLD.

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

[1] Watanabe, Tsuneo, Soil and Seed Fungi, Morphologies of Cultured Fungi and Key to Species, 2nd Ed., 2002, CRC Press, ISBN 0-8493-118-7

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.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.

Building inspection education & report writing systems from Carson, Dunlop & Associates Ltd

Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
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 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

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) - The Atlas of Clinical Fungi is also available on CD ROM
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 at /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 [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol


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