Moisture Gradients in Building Materials Tell Where to Look for Mold InspectAPedia® -
An explanation of the relationship between level of moisture and mold growth in common building materials like drywall and paneling
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This article provides an explanation of An explanation of the relationship between level of moisture and mold growth in common building materials like drywall and paneling.
The photo at page top shows three different mold genera/species, each occurring at a different elevation on this basement wall. The probable
reason for these distinct areas of growth was that water on the basement floor soaked the bottom section of drywall while upper sections
were less wet, each attracting a different mold genera and species.
See Wall test cuts to spot hidden mold for a discussion of mold hidden in wall cavities. See SAMPLING DRYWALL for a discussion of mold on drywall. Also see MOLD RESISTANT DRYWALL for a discussion of that product type as well as a list of drywall or gypsum board industry standards and drywall product MSDS sheets.
Moisture Gradients and Mold Growth on Drywall and Other Building Surfaces
This document 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. This mold inspection 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.
This section explains that because different mold genera/species will grow on the same building material at different moisture levels,
it is easy to make a mistake in inspecting or testing mold in buildings by ignoring the light-colored but more problematic molds that
are often found higher on drywall above the more obvious "black mold" people see there.
Keep in mind that different molds like different moisture, temperature, and food.
One reason
that S. chartarum has been "over-reported" as a problem in some studies is that the
field "experts" didn't look for lighter molds, and maybe they didn't even carry a flash
light.
The photo (left) shows three tape samples being taken from different heights on a
laundry room wall. Three different mold species were found, one in each
area. Only the lowest black mold was obvious.
In this wall test of three molds which were growing quite close together, I've marked each tape sample
so that you can see where it was on the wall. #1 =Stachybotrys chartarum,
#2 = Ulocladium chartarum, #3 = Aspergillus sp.. - it is this third mold which, in a larger quantity,
would be airborne and more likely to bother building occupants. Yet nearly 100% of home owners and 80% of industrial hygienists and
90% of home inspectors who send mold samples to our lab are going to tape-sample only the "dark mold" on this wall.
Why are there three different genera/species on this drywall? Most likely because each of them prefers a different moisture level
in the paper which they're digesting. I can generally track the mold genera up the wall as a function of the moisture gradients in
the wall. When a wall has been wet because of wet floor conditions, the drywall and in-cavity wall insulation will be wettest at
the wall bottom.
Be sure to review our notes above on use of lighting at Use of a flashlight to find mold
since if you don't know exactly how to use a flashlight, as simple as it seems, you're not going to find important light-colored
molds 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
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 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.
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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