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ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
MOLD: A COMPLETE GUIDE to TEST CLEAN PREVENT
ACTIVITY of MOLD in BUILDINGS
AGE of MOLD - Old is the Mold?
AIR CLEANER PURIFIER TYPES
AIR FILTERS for HVAC SYSTEMS
AIR TEST SAMPLING CASSETTE STUDY
AIRBORNE MOLD COUNT NUMBER GUIDE
AIRBORNE PARTICLE ANALYSIS METHODS
ALLERGEN TESTS for BUILDINGS
BROWN HAIRY BATHROOM MOLD
BIBLIOGAPHY for ENVIRONMENTAL HEALTH, MOLD, IAQ
BLACK MOLD, HARMLESS COSMETIC
BLACK MOLD, TOXIC & ALLERGENIC
BLEACHING MOLD, Advice about
BOOK MOLD, Moldy Book Cleaning
BOOKSTORE - ENVIRONMENTAL
CACTUS FUNGI / MOLD
CAR MOLD CONTAMINATION
CARPET DUST IDENTIFICATION
CARPET PADDING ASBESTOS, MOLD, ODORS
CARPET FUNGICIDAL SPRAY
CARPET STAIN DIAGNOSIS
CARPET & other STAIN TESTS
CARPET TEST PROCEDURE
CARPETING & INDOOR AIR QUALITY
CHAIN OF CUSTODY - TEST SAMPLE
CLEARANCE INSPECTIONS - MOLD CLEANUP
DIRECTORY of MOLD / ENVIRONMENTAL EXPERTS
DIRT FLOOR MOLD CONTAMINATION
DISINFECTANTS & SANITIZERS, SOURCES
DISINFECTING BUILDINGS with BLEACH
DO-IT-YOURSELF MOLD CLEANUP WARNINGS
DUST ANALYSIS for FIBERGLASS
DUST, HVAC CONTAMINATION STUDY
EFFLORESCENCE, Salts & White / Brown Deposits
FEAR of MOLD - MYCOPHOBIA
Fiberboard Insulation Sheathing Mold
FIBERGLASS INSULATION MOLD
FIND MOLD, ESSENTIAL STEPS
MOLD in BUILDINGS
FIRE DAMAGE vs MOLD DAMAGE
FLOODS IN BUILDINGS-mold
FOXING STAINS on books & papers
FUNGICIDAL SPRAY & SEALANT USE GUIDE
GAS DETECTION INSTRUMENTS
GAS EXPOSURE EFFECTS, TOXIC
GAS EXPOSURE LIMITS & STANDARDS
GAS TEST PROCEDURES
HOUSE DUST ANALYSIS
HOUSE DUST COMPONENTS
HUMIDITY CONTROL & TARGETS INDOORS
LAB PROCEDURES MICROSCOPE TECHNIQUES
LIGHT, GUIDE to FORENSIC USE
MEDIA BLASTING for MOLD REMOVAL
METHANE GAS SOURCES
MICROSCOPE DIGITAL PHOTOGRAPHY
MEDIA BLASTING for MOLD REMOVAL
METHANE GAS SOURCES
MICROSCOPE DIGITAL PHOTOGRAPHY
MILDEW ERRORS, IT's MOLD
MILDEW REMOVAL & PREVENTION
MOISTURE CONTROL in BUILDINGS
MOLD: A COMPLETE GUIDE TO MOLD
MOLD EXPERT, WHEN TO HIRE
MVOCs & MOLDY MUSTY ODORS
MYCOPHOBIA, STAINS MISTAKEN for MOLD
MYCOTOXIN EFFECTS of MOLD EXPOSURE
ODORS GASES SMELLS, DIAGNOSIS & CURE
RENTERS GUIDE TO MOLD & IAQ
ROBIGUS & Wheat Rust Fungus
SMELL PATCH TEST to Track Down Odors
STAINS on & in BUILDINGS, CAUSES & CURES
THERMAL IMAGING MOLD SCANS
TRAPPED MOLD BETWEEN WOOD SURFACES
UV LIGHT BLACK LIGHT USES
VAPOR BARRIERS & CONDENSATION
VENTILATION in BUILDINGS
VOCs VOLATILE ORGANIC COMPOUNDS
WATER ENTRY in buildings
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.
MOLD in BUILDINGS 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.
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Introducing Soil Fungi - "Dirt Mold"
A broad range of fungal species among at least seven genera may be found growing on or in soil  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. This article does not address the much larger topic of the genera of soil fungi. For that topic see Tsuneo Watanabe, Pictorial Atlas of Soil and Seed Fungi, Morphologies of Cultured Fungi and Key to Species, [at Amazon.com] Second Ed., CRC Press 2002, ISBN 0-8493-1118-7. [Disclosure: Amazon pays us a pathetic pittance on the sale of books listed here].
What is the Significance of Soil Fungi In a Building?
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 MOLD in BUILDINGS 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
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.)
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 PHOTOS. 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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