Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
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
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?
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.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved. Author Daniel Friedman.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved.
How to Test or Sample Building Drywall, Gypsum Board, "Sheetrock" and other Building Surfaces for Mold Using Clear Adhesive Tape
As I've explained in various articles and at DUST / MOLD TEST KIT INSTRUCTIONS, different mold genera/species will be found growing on the same or nearby sections of drywall on a building surface, depending on several variables.
If the largest contiguous mold area in a building is trivial in amount, say 1 sq .ft., we would not test it unless we thought that the mold we see is representative of a larger mold problem I cannot see. Small areas of mold should simply be removed.
For larger areas of mold (certainly if more than 30 sq .ft. of area is moldy or if mold is growing on many surfaces in a building), you are looking for the dominant species present and particularly allergenic or toxic species present in the environment.
The photo at page top 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 HIDDEN MOLD in CEILINGS / WALLS we discuss finding mold on the wall cavity side of drywall.
This article is part of our '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.
How to Decide Where to Sample for Mold and How Many Mold Samples To Collect
Collect one mold tape sample per location; do not use the same tape to sample from multiple locations.
This condition often occurs, but the different genera may be as close as inter-mixed and even overlapping in the same area, to growing several feet apart on the same wall, to growing in the same building but on different materials on different surfaces.
In this case, tape sample #1, the bottom mold, was Stachybotrys chartarum, tape sample #2, the middle mold, was Cladosporium sphaerospermum, and the top tape sample, #3, was Aspergillus flavus. Of these three, the Aspergillus is the easily-airborne toxic spore which is more likely to be a problem in the building if it is present in sufficient quantity.
At MOLD LEVEL REPORTING we explain the errors you can expect if you do not choose a properly-representative area of a surface when collecting mold or dust samples and at MOISTURE GRADIENTS & MOLD we explain why we find different mold genera/species at different locations on moldy drywall.
How to Prepare & Save Mold Tape Samples for Mailing to a Mold Test Laboratory
In this photo detail you'll see that using a new and clean zip-lok™ bag, we placed several surface tape samples on the same bag. If you can't assure that the bag surface is clean between tape sampling, use a new bag for each sample.
Are you collecting too many mold test samples?
There are nearly always multiple mold species present in any environment where mold producing conditions are present.
We sample surfaces likely to host different molds, focusing on surfaces which appear to represent mold or mold-suspect material growing over large areas in the building. Don't collect and send 50 samples. If you find you want to collect a great many samples it would probably be smarter and more economical to bring in an expert to survey the building and who can sample more strategically.
Interrupted Mold Growth Pattern on Building Drywall - Why Does Mold Growth Sometimes Stop in Straight Lines?
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:
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.
How to Relate Mold Growth Pattern to Building Leaks or Moisture Vairations
I attached three mould photos for you. Can you help me to find out the possible reasons? - L.Y. 6/4/2013
Reply: Summary of common reasons for mold growth on drywall
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem. That said, here are some things to consider:
Possible reasons for indoor mold growth ?
In all cases of indoor mold growth the mold needs food (wood, paper, organic material), oxygen, and water; some molds thrive on light, some are tolerant or intolerant of UV, and other factors.
Moisture, water, leaks, condensationa are key determinants in indoor mold growth
Of all of these, water is the key necessary ingredient which we can track and which is inviolate - that is, no water, no moisture = no problem mold growth.
But I note that your middle photo looks as if it is a ceiling and because there is a vent therein I suspect this may be over a bathroom; Common moisture sources for such an area might include
The density of mold growth in your photos suggests that there have been leaks from above. But in some cases even without actual water leaks into a ceiling or wall we can see dense mold growth on building drywall caused by other wet building conditions (flooding of the floor for example, or a heating or steam pipe leak).
The fact that the mold seems to track or be more dense along lines resembling either drywall joints or actual locations of framing would argue for either leaks from above penetrating at drywall butt joint seams or quite often, temperature differences (wood framing in contact with drywall produces cooler temperature than insulated ceiling cavities).
Temperature variations can in turn invite higher levels of condensation on cooler surfaces in those areas. We also see this effect in THERMAL TRACKING & THERMAL BRIDGING
So even when we don't see leak stains showing a water source, the mold growth pattern might track moisture gradient in the materials and thus suggest something about its cause.
You will need to remove the moldy drywall in any case, as well as any insulation that has been wet or exposed to mold.
That will let you inspect the wall or ceiling cavity for leaks as well as to check that the bath vent fan is actually venting and is properly used.
`Actually I know very little knowledge about mould. My landlord said the mould was caused by the lack of heat. Can you show me some ideas?
Does the water stain of the second picture show water leakage? This house is more than 40 years old.
There is no indoor ventitaltion system, the fan in the bathroom has been blocked for long time and the fan had not been insulated well.
There's no fan to transfer gas to outside in the kitchen. - Y. 6/5/2013
Mold is is not directly caused by lack of heat - cooler temperatures in fact retard mold growth, if all other conditions are equal. But lack of heat that leads to condensation problems or to a frozen burst pipe and leak can indeed cause or encourage indoor mold growth.
And I would agree that heating a building, as it dries a building, would avoid problem mold growth provided that there are not leaks or abnormal moisture sources.
If there is mold there is a condensation or leak problem to find and fix. If the mold is on the wall cavity side of the plastic then there are leaks into the wall cavity - either water leaks or air leaks, perhaps combined with incomplete or improper insulation. I'd have to see more detail to have a more confident opinion. From your photo I'm not even sure what's ceiling and what's wall.
Some speculative examples of what could be going on include:
The suggestions I made earlier about tracking down leak and moisture sources should, perhaps in this case, be combined with inspection for air leaks into the cavity from indoors or from outside.
At What Moisture Level Shoudl Drywall Simply be Removed?
Reader question: 1/30/2014 Phil said:
What % of moisture or water penetration into Drywall can it reach before it can not be dried and has to be removed. Also, if there is a time limit on when you have to start the drying process.
Phil, that's an interesting question and I haven't thought about wet drywall quite that way. Let's try this:
Watch out: however if drywall is really soaked we have to ask where the water came from, where it flowed in the building, and what else got wet. For example, if drywall is soaked because of water flowing through a ceiling or wall cavity, if we do not open that cavity, remove insulation, and get the entire cavity and all materials dry quickly enough, we're likely to have a costly mold contamination problem there. In such cases, deciding to keep or leave drywall in place because of its surface or room-side moisture could be a mistake.
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
No FAQs have been posted for this page. Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
HTML Comment Box is loading comments...
Technical Reviewers & References