Where to Make Wall or Ceiling Test Cuts to Check for Mold Contamination InspectAPedia® -
How & Where to Make Wall Test Cuts to Find and Test for Mold in Buildings
Use of a borescope to find hidden mold in building wall or ceiling cavities
Growth pattern of some toxic molds in wall cavities maps insulation installation patterns
Strategies for choosing where to make test cuts to check walls or ceilings for hidden mold contamination
How to find and test for hidden mold in buildings
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This article discusses how, why, when, and where to make wall test cuts to find and test for hidden mold contamination or growth in buildings.
The fact that mold is "hidden" in buildings does not mean one cannot find it. We look by context: where do we see leak stains,
or where do we see building practices most likely to have produced a hidden leak or moisture problem? Ice dam leaks in walls,
hidden plumbing leaks, roof spillage by the foundation, are all common clues that often track to a wet building wall or ceiling cavity and
from there to a hidden mold problem which may need to be addressed.
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 discusses the variation in type of mold growth found on drywall or gypsum board at different heights above a wet floor.
This article on mold inspection and testing discusses the use of test cuts in building surfaces to explore building cavities for hidden mold. Since even small cosmetic damage
to buildings is something to avoid when possible, we also discuss how to decide when a test cut is justified, and now to explore building
cavities with the minimum damage. This document is part of a longer article which 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 MOLD TEST KITS for DIY MOLD 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.
Unless a building area is already visibly damaged or moldy, we proceed with as little damage or "invasiveness" as possible. Often no invasive cuts are needed to see into a building cavity.
Text and photo illustrations in this section are roughly in order of degree of invasiveness.
Often an experienced inspector who knows where to look, can reach very reliable conclusions
about hidden mold with no damage to a property at all. Or we can perform non-damaging invasive inspection such as the careful removal of trim for further inspection.
Use of a bore scope to inspect building cavities
Where a 2" diameter hole is not permitted, we may explore using this small borescope which requires a hole about the diameter of a pencil.
Often this probe can be inserted behind loose trim or in existing building openings to permit a limited-access view of building cavities without any destructive cuts at all.
Photos demonstrating use of a hole cutter and drill to explore buildings for hidden mold
We use several sizes of hole cutter bits to explore areas where building history or visual clues suggest a high probability of hidden mold growth between plies of building material. Examples include buildings which have been "renovated" by the
installation of additional layers of drywall.
The second photo (above right) shows that pink and other colored mold was found growing on the hidden or cavity side of the drywall where we made this cut. The building had been exposed to prior leaks
into wall cavities from the floor above.
A "water extraction" company had cut holes along the bottom of the wall in each stud bay to, as they claimed, extract the water. I have never once found this approach successful. There was no air
circulation throughout the wall during the drying procedure, and worse, the process was begun too late after the leak event, and worst still, no one inspected to evaluate the effectiveness of the procedure.
After the water extractors
left a renovation contractor was engaged to wash and paint all of the interior wall and ceiling surfaces. Most of them were badly mold-contaminated on their hidden side and had to be removed for proper mold remediation and cleanup.
The photo at above right shows us cutting a round hole in a wall to expose the wall cavity. We cut high enough above the floor to avoid the sill plate and to give access to the wall cavity itself. We cut close to but not on top of a wall stud, so that when examining the wall cavity we can examine:
The cavity side of drywall plug which was removed, checking it for visible mold
The condition of insulation in the wall cavity - if any. It may be necessary to vacuum-test wall insulation to test for mold since fiberglass insulation can be moldy but look quite clean.
The condition of nearby upper surface of horizontal sill plates to check for mold growth or evidence of leaks
The condition of nearby vertical surface of a wall stud to check for visual evidence of mold growth or leaks
The condition of the wall cavity-side of the opposing drywall or exterior wall sheathing.
Do not fail to check all of these surfaces. It is common to find more severe mold growth on the drywall of one side of a wall cavity than on the other. This happens when water has run down one surface but not on another.
How to Find or Test for Inter-ply mold, between layers of building materials
In Poughkeepsie NY we visited our friend's son who had been hired by a real estate
property "flipper" to "deal with mold" by laminating another layer of drywall over all of the very moldy walls and ceilings
in the home.
It is likely that future occupants will eventually discover and be a bit upset by this shortcut. Careful cutting through layers of material can expose mold on inter-ply layers such as shown in this ceiling cut.
Larger Drywall test cuts to check for hidden mold contamination
Where we have justification to proceed we may cut a 2" x 3" hole in drywall to peer into a wall cavity. This opening, like the plug cut openings discussed above, is trivial to patch in drywall or plaster, but permits a more reliable inspection of the building cavity interior than a borescope. Where damage is already
extensive, there is nothing lost, no material to preserve, and a still larger opening may be cut, or multiple openings, in order to confirm the extent of contamination and thus the extent of demolition and mold cleanup needed.
Memnoniella echinata - a toxic black mold in a wall cavity: During an investigation of a high-rise apartment in a large U.S. city, I was asked to evaluate
black mold visible on basement floor joists in a kitchen.
Our mold inspection procedure includes a screen of the entire living unit which in this case was a large multi-room apartment.
At the far end of the apartment, remote from
the kitchen and its leaks and mold, I found evidence of other leaks into and below an expensive cherry-wood floor.
We traced leaks to an air conditioning wall unit whose condensate was draining into the floor rather
than into its drain.
The photo (left) shows our initial test cut into the wall cavity. The next photo below shows a closeup of the cavity interior.
We chose an area to make a "test cut" into the wall cavity where we thought there had been the most water exposure.
The result is in the photo you see above - there was black mold in the wall cavity on the hidden surface of
the drywall.
A simple laboratory test confirmed what our nose and throat were suggesting at the inspection - this was a particularly irritating mold, which we identified in our lab as Memnoniella echinata.
My work plan for this New York City apartment included an expansion of the original scope to cut open the lower drywall around the room where our test cut identified this problematic mold. I asked the remediator to continue removing drywall until there was at least a 24" clear margin of no visible mold.
The result was dramatic - water had run in the steel
channel formed by the metal sill plate, and had followed the wall around the apartment, producing a significant reservoir of Memnoniella echinata or "black mold" which needed to be removed. (In case you missed it, it is complete nonsense
to assume that "black molds" are always a problem and even more erroneous to include light colored and hard to see molds which often are a more significant hazard in buildings.)
Another "toxic black mold", Memnoniella echinata is particularly toxic and irritating. It's a member of the Stachybotrys family but unlike Stachybotrys chartarum, a sticky spore that tends to stay in its place, M. echinata is more easily airborne and I often find
it in the air when it's growing in the building. It's more of a problem than its famous brother.
The photographs provide a second warning: a small amount of mold on the visible side of a wall [Memnoniella wall] may be a clue that there is a much bigger problem inside the wall cavity. In the first photo you are looking into a small 3" x 3"
opening I made to see conditions in the wall cavity. Don't do this if at risk people are around as you may be spreading spores in the air.
This photo shows the growth pattern on the cavity face of drywall on the opposite side of the drywall from where
we cut and removed a larger section of drywall during remediation.
You can see that the Memnoniella echinata exhibits
an odd growth pattern on the wall which maps the areas of contact or non-contact of wall insulation with the
paper drywall surface in this cavity.
This photo shows the extent of mold growth which had been hidden in the wall cavity after the remediation contractor cut away one side
of the drywall as I had asked.
You'll see that a large area of moldy drywall was involved, and that the remediation project needs to expand
to include removing the opposing wall drywall and thus other rooms in the apartment.
This drywall test cut to look for hidden mold was made in a basement where we observed water stains on the drywall.
We discovered a plumbing drain, unknown to the
building owner, and a history of leaks leading to moldy insulation and drywall in this basement corner.
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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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