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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, HOW OLD
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 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 PREVENTION
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
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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Where to look for "Invisible Mold" in buildings - important mold reservoirs that cannot be detected by visual inspection
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.
See Mold in Fiberglass Insulation for details of the occurrence of mold contamination in building insulation, and see Vacuuming building cavitiesas a screen for building mold as well as VACUUMING BUILDING INSULATION for finding mold-contaminated fiberglass.
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:
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Technical Reviewers & References
Allergies, Allergens, Allergy Testing in buildings - References & Products
Mold Contamination Testing, Cleanup, Prevention: references & products
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.