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Mobile ViewENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY MOLD: A COMPLETE GUIDE to TEST CLEAN PREVENT ACCEPTABLE MOLD LEVEL ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD ACTIVITY of MOLD in BUILDINGS AIRBORNE MOLD SPORE COUNT ACCURACY AIRBORNE PARTICLE ANALYSIS METHODS ALLERGEN TESTS for BUILDINGS ALLERGENS in BUILDINGS, RECOGNIZING ALLERGY TESTS for PEOPLE ALLERGY TEST ACCURACY ANIMAL ALLERGENS / PET DANDER ANIMAL ENTRY POINTS in BUILDINGS ASBESTOS CLEANUP COMPANIES ASBESTOS ROOFING / SIDING DUST ASBESTOS IDENTIFICATION IN BUILDINGS ATTIC MOLD BASEMENT MOLD BASEMENT MOLD WATER IMPACT BASICS YOU NEED to FIND, TEST, REMOVE MOLD BASKETBALL MOLD SYNDROME - BBMS BATHROOM MOLD BROWN HAIRY BATHROOM MOLD BIBLIOGAPHY for ENVIRONMENTAL HEALTH, MOLD, IAQ BIOGAS PRODUCTION & USE BIOLOGICAL POLLUTANTS BIOLOGICAL POLLUTANTS in the HOME - EPA BLACK MOLD, HARMLESS COSMETIC BLACK MOLD, TOXIC & ALLERGENIC BLEACHING MOLD, Advice about Bisphenol-A, BPA BOOK MOLD, Moldy Book Cleaning BOOKSTORE - ENVIRONMENTAL BUYERS GUIDE - home inspections for mold CARPET DUST IDENTIFICATION CARPET MOLD CONTAMINATION CARPET STAIN DIAGNOSIS CARPET & other STAIN TESTS CARPET TEST GUIDE CARPETING & INDOOR AIR QUALITY CAT DANDER CRAWLSPACE MOLD DO IT YOURSELF MOLD CLEANUP DRYWALL MOLD DUST ANALYSIS for FIBERGLASS DUST SAMPLING PROCEDURE EFFLORESCENCE, Salts & White / Brown Deposits ESSENTIAL STEPS IN FINDING MOLD FEAR of MOLD - MYCOPHOBIA Fiberboard Insulation Sheathing Mold FIBERGLASS INSULATION MOLD FIBERGLASS PARTICLE CONTAMINATION TEST FIELD INVESTIGATION SERVICE FIND MOLD, ESSENTIAL STEPS FIND MOLD in BUILDINGS, HOW TO FIRE DAMAGE vs MOLD DAMAGE FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP FLOODS IN BUILDINGS-mold FLOORING MATERIALS, Age, Types FUNGICIDAL SPRAY & SEALANT USE GUIDE GASES, EXPOSURE, TESTING GAS MEASUREMENT TOOLS Gas Toxicity Levels GAS EXPOSURE EFFECTS GAS TEST PROCEDURES House Dust Analysis HIDDEN MOLD, HOW TO FIND HUMIDITY CONTROL & TARGETS INDOORS INDOOR AIR HAZARDS TABLE INDOOR AIR QUALITY & HOUSE TIGHTNESS INDOOR AIR QUALITY IMPROVEMENT GUIDE INSULATION INSPECTION & IMPROVEMENT INSULATION MOLD ITCHY FABRICS LABORATORY SERVICES LAB PROCEDURES MICROSCOPE TECHNIQUES Legionella Legionnaires' Disease Legionella BACTERIA & HVAC Equipment MEDIA BLASTING for MOLD REMOVAL METHANE GAS SOURCES MICROSCOPE DIGITAL PHOTOGRAPHY MILDEW in BUILDINGS ? MILDEW ERRORS - MOLD PHOTOS MILDEW REMOVAL & PREVENTION MOISTURE CONTROL in BUILDINGS MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD ACCEPTABLE MOLD LEVEL ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD MOLD CLEARANCE: FOLLOWUP STEPS ATTIC MOLD BASEMENT MOLD BASEMENT MOLD WATER IMPACT BASICS YOU NEED to FIND, TEST, REMOVE MOLD BASKETBALL MOLD SYNDROME - BBMS BIBLIOGAPHY for ENVIRONMENTAL HEALTH, MOLD, IAQ BIOGAS PRODUCTION & USE BIOLOGICAL POLLUTANTS BIOLOGICAL POLLUTANTS in the HOME - EPA Bisphenol-A, BPA BLACK MOLD, HARMLESS COSMETIC BLACK MOLD, TOXIC & ALLERGENIC BLEACHING MOLD, Advice about BOOK MOLD, Moldy Book Cleaning BOOKSTORE - ENVIRONMENTAL BUYERS GUIDE - home inspections for mold CARPET MOLD CARPET STAIN DIAGNOSIS CARPET & other STAIN TESTS CARPET TEST GUIDE CAT DANDER CRAWLSPACE MOLD DO IT YOURSELF MOLD CLEANUP MOLD CLEANUP - SAFETY WARNINGS DRYWALL MOLD DUST ANALYSIS for FIBERGLASS DUST SAMPLING PROCEDURE EFFLORESCENCE, Salts & White / Brown Deposits ESSENTIAL STEPS IN FINDING MOLD FEAR of MOLD - MYCOPHOBIA Fiberboard Insulation Sheathing Mold FIBERGLASS INSULATION MOLD FIND MOLD, ESSENTIAL STEPS FIND MOLD in BUILDINGS, HOW TO CHOOSE SAMPLE POINT SAMPLING DRYWALL MOLD TESTING & SAMPLING MISTAKES FLASHLIGHT HELPS FIND MOLD HIDDEN MOLD, HOW TO FIND INDOOR AIR QUALITY & HOUSE TIGHTNESS INDOOR AIR QUALITY IMPROVEMENT GUIDE INDOOR AIR QUALITY METHODS COMPARED INSULATION MOLD ITCHY FABRICS LAB PROCEDURES MICROSCOPE TECHNIQUES LEED GREEN BUILDING CERTIFICATION LEED Building Designation & IAQ MILDEW in BUILDINGS ? MILDEW ERRORS - MOLD PHOTOS MILDEW REMOVAL & PREVENTION MOISTURE CONTROL in BUILDINGS MOLD: A COMPLETE GUIDE to TEST CLEAN PREVENT MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD MOLD ACTIVITY in BUILDINGS MOLD AGE - Old is the Mold? Single-leak mold Multi-event mold Mycologists' view on age of mold Building scientists' view on age of mold Conditions affecting fungal growth Conditions permitting mold age assessment Determine if Mold Contamination is Active? MOLD APPEARANCE - WHAT MOLD LOOKS LIKE Black Mold Brown Mold Green Mold Red Mold Yellow Mold White Mold Invisible Mold Meruliporia Mold Photographs Mildew Photographs Recognize Cosmetic Mold Recognize Harmless Black Mold MOLD GROWTH ON SURFACES, PHOTOS MOLD APPEARANCE - STUFF THAT IS NOT MOLD HARMLESS INDOOR PARTICLES BASKETBALL MOLD SYNDROME - BBMS Black stains from soot/thermal tracking Black stains from animals Black cosmetic mold Efflorescence & white or brown deposits House dust Pollen Sprayed foam insulation White stuff that is not mold Wood sap MOLD ATLAS & PARTICLES INDEX MOLD by MICROSCOPE MOLD in the PETRI DISH, PHOTOS Mold on Books, Book Conservation MOLD CLASSES, HAZARD LEVELS MOLD CLEANERS - WHAT TO USE MOLD CLEANUP COMPANIES MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD MOLD CLEANUP with BLEACH MOLD CLEANUP - WOOD FLOORING MOLD CLEANUP - WOOD FRAMING & PLYWOOD MOLD CLEANUP HEALTH RISKS MOLD CLEANUP MISTAKES to AVOID MOLD CLEANUP - SAFETY WARNINGS MOLD CLEARANCE INSPECTIONS MOLD CULTURES MOLD DETECTION & INSPECTION GUIDE MOLD DOCTORS - ENVIRONMENTAL MEDICINE MOLD EXPERT, WHEN TO HIRE MOLD EXPOSURE, FOOD HAZARDS MOLD EXPOSURE RISK LEVELS MOLD EXPOSURE STANDARDS MOLD FREQUENCY in BUILDINGS MOLD GROWTH ON SURFACES, PHOTOS MOLD GROWTH on SURFACES, TABLE OF MOLD INSPECTORS & MOLD TESTERS MOLD KILLING GUIDE MOLD LAB REPORTS MOLD LEVEL REPORTS MOLD LEVELS IN BUILDINGS MOLD by MICROSCOPE MOLD ODORS, MUSTY SMELLS MOLD PREVENTION GUIDE MOLD RELATED ILLNESS MOLD SAFETY WARNINGS MOLD SPRAYS, SEALANTS, PAINTS MOLD TEST KITS MOLD TEST KITS for DIY MOLD TESTS MOLD TESTING SERVICES MOLD TEST METHODS, ACCURACY MOLD TEST PROCEDURES MOLD TEST REASONS MVOCs & MOLDY MUSTY ODORS MYCOTOXIN EFFECTS of MOLD EXPOSURE Nanomaterials Hazards NOISE / SOUND DIAGNOSIS & CURE ODORS & SMELLS DIAGNOSIS & CURE ODOR DIAGNOSIS CHECKLIST RENTERS & TENANTS GUIDE TO MOLD STAIN DIAGNOSIS & GUIDE TECHNICAL & LAB PROCEDURES THERMAL TRACKING Indicates Heat Loss TRAPPED MOLD BETWEEN WOOD SURFACES VENTILATION in BUILDINGS VINYL Siding or PLASTIC Window ODORS in Buildings VINYL CHLORIDE HEALTH INFO WALL SIDING TRIM & FINISHES WALL FINISHES INTERIOR WATER BARRIERS, EXTERIOR BUILDING WATER ENTRY in BUILDINGS WATER ODORS, CAUSE CURE World Trade Center Collapse Dust Photos More Information |
Guide to testing mold on building drywall: This article describes proper procedures for sampling mold on drywall in buildings. Because moldy drywall or "sheetrock" is often the consequence of a building flood or wet floor, the moisture gradient in drywall varies at different heights above the floor surface. Because different mold genera/species vary in their hydrophilic nature (some molds love water more than others), different mold genera/species are likely to be found at different heights on a building wall. Which molds are most important to sample? InspectAPedia offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/Contact.htm.The photo above shows several colors of mold on a drywall surface. Still more mold may be present but still lighter in color and harder to see. Each of these may be a different mold genera or species. Which molds that we see on a building surface should be sampled? We explain the answers here. At Wall test cuts to spot hidden mold we discuss finding mold on the wall cavity side of 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. 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 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 chapter is part of a 'how to' photo and text primer on finding and testing for mold in buildings using simple clear adhesive tape on suspect or visibly moldy surfaces. Also see MOLD GROWTH ON SURFACES, PHOTOS and MOLD APPEARANCE - WHAT MOLD LOOKS LIKE. © Copyright 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.
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In our photographs shown above the thick black mold growth on drywall in a wet basement appears to nearly "stop" in a neat horizontal line just about four feet from the floor surface. Why?
Stachybotrys chartarum, which dominated the mold on this drywall, really likes wet conditions. As we explained above, the genera/species of mold growth may vary on a surface of the same material as a function of variation in moisture levels in the material.
In our photo at above right we show by having made a test cut into the moldy drywall that mold growth stopped its rapid advance up the drywall when it encountered the horizontal tape joint between the lower and upper runs of drywall in the building. We have found two common explanations for this observation:
I had energy efficient windows installed in my townhouse over a year ago. This past spring one of the master bedroom windows leaked after a rain storm because the caulking failed. The company immediately came out and recaulked the window and it hasn't leaked since.
[Photo at left provided by InspectAPedia, taken from a New Jersey home and not the building discussed by this reader, shows mold growth on drywall and on wallpaper beneath a leaky window. A single rainstorm combined with the window having been left partly opened caused this mold growth.
After checking the basement ceiling cavity below this window as well as in the wall cavity itself, our investigation found that the total moldy area was less than 30 sq.ft. and the mold cleanup could be handled as a normal renovation job. More examples of mold growth on and in wall cavities and hidden by wallpaper are shown at MOLD GROWTH ON SURFACES, PHOTOS - Ed.]
My concern is that I now have a water stain under the window on the drywall, and since I have a mold allergy, I'm wondering if there might be mold on the inside of the drywall. I read your article on testing the dry wall but as mentioned in the article would rather not cut into it unless it's necessary. I looked at other articles but didn't see one with a picture resembling the water stain I'm concerned about. What would you recommend?
By the way, this is a very helpful website. I was considering using ozone for any possible mold in my place but see from your article that's not a good idea.
Continued: I emailed you recently about the possibility of mold forming on the inside of drywall under a window that leaked last spring when it rained.
I contacted a bonded company about replacing the drywall. The gentleman I spoke on the phone with told me that he's attended mold seminars and that mold requires an ongoing source of water or moisture over an extended period of time to grow. In his opinion, since my leak occurred only once during a rain storm that lasted an hour or so, there's little or no chance mold could grow on the inside of the drywall under the window. He also said that since the water stain is barely visible, this is more reason to conclude there's no mold on the inside of the dry wall.
I thought it would be a good idea to check this on your website, but didn't find any topic that seemed related to the conditions for mold formation, so I thought I should email you. Is what he says about mold formation accurate? And if so, is it reasonable to conclude that there's probably no mold on the inside of the dry wall under the window that leaked?
I'm hoping he's right, because I won't have to replace the drywall. I'll replace it if necessary, though.
Thanks again for your help. G.N.
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with mold, hidden mold, and with tracking down just how much water leaked into the building and where it went.
First, how disappointing that your new windows leaked - certainly a wet wall below a leaky window is not particularly energy efficient, and indeed it could become a mold reservoir.
The risk of a mold problem that you can't see but that is significant enough to merit removal is not something I nor anyone should guess at by email nor by telephone (that is, with no building inspection) with so little information. MOLD EXPERT, WHEN TO HIRE provides advice on deciding (or not) to hire someone to inspect and test for mold contamination.
Watch out: mold testing alone, without a building inspection, case history, and occupant interview, is not reliable.
I would not rely on "mold tests" - a test, especially an air test for airborne mold, performed without an expert diagnostic inspection of the building is just not reliable in cases where the result is "negative".
Continued reply: G., your bonded company expert is mistaken, as you can see in our example photo above showing mold growth in the wall cavity and behind wallpaper below a window following a single event leak.
A single water entry event can cause mold growth in a building cavity, on the wall cavity side of drywall, in the wall insulation, on the kraft paper insulation facing, on the building structural wall wood studs or cavity side of the exterior wall sheathing.
Your expert would, however, be correct, if s/he asserted that the extent or size or severity of mold growth from a single event leak depends on the size of the leak, the amount of water entering the cavity, where it went, what materials got wet, and the moisture exit rate from the building cavity.
Unlike your expert, beyond that advice I'm reluctant to promise what is or is not in a building cavity on a building I've not studied. Often an expert on site finds evidence of chronic leaks that a normal building owner may never have noticed. Very often very small leaks or wet spots do not produce a significant problem mold reservoir.
But because building wall or ceiling cavities dry out very slowly, leaks into a wall or ceiling, even from a single event, can initiate problem mold growth in those areas. In general, if a building interior or building cavity interior contains mold friendly organic materials such as wood, paper, drywall, fabrics, drywall, mold growth can be expected to occur if the area remains wet for 24-48 hours. Low temperatures can sometimes slow down mold growth so a building that was wet during freezing weather may have a bit more time.
When the building cavity finally has dried, several conditions are likely to occur:
In general, if there has been anything but the most absolutely trivial leakage into a building wall or ceiling cavity, and if thus we decide to investigate, I recommend choosing the one or two most suspect leak areas, where there is the most evidence or suspicion of the area that received the most water or was the most wet. In those areas I'll make a small test cut, perhaps 2" x 4" into the ceiling or wall, through the drywall. There we perform a visual inspection for visible mold on all surfaces and materials; if there is insulation present we also collect a vacuum sample of that material, and we collect tape samples of any visible mold on any of the newly exposed surfaces.
If that most-suspect area is "clean" of any strong suggestion of mold contamination, we don't cut or dig further without some other compelling reason to do so.
What is appropriate when there has been building leakage and where there is a concern for possibly significant hidden mold contamination is to make a decision about whether hiring an expert is justified in a particular case - see MOLD EXPERT, WHEN TO HIRE for advice on making that decision.
More photographs and examples of mold growth on drywall are found at Mold on Drywall or Sheetrock®. Also see HIDDEN MOLD, HOW TO FIND.
Questions & answers about mold growth on building drywall surfaces and about mold testing procedures.
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The Mold Information Center: What to Do About Mold in Buildings, When and How
to Inspect for Mold, Clean Up Mold, or Avoid Mold ProblemsMold 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.
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