How to Clean or Remove Toxic Mold in buildings - A Homeowner's or Apartment Owner's Guide
InspectAPedia® -
Here is a step by step guide on what to do about mold in a building
How to clean or remove mold properly
Mold clearance inspections after cleanup
Questions & answers about the best procedures to get rid of mold and mold smells in buildings
This article describes how toxic or allergenic mold is removed from buildings - mold cleanup, or mold remediation. We discuss how to physically remove problem mold (don't just spray over it), what cleaners can be used for mold removal, and use of bleach in mold cleanup and removal jobs.
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We also list related mold cleanup or remediation articles that address special problems such as mold odors, mold removal from irregular surfaces, and stains or odors on roofs or in cars. This is article is part of our series starting at ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD,
a document which provides an easy to understand step-by-step guide for
dealing with toxic or allergenic indoor mold and other indoor contaminants: what to do about mold.
Protect the occupants and yourself from mold, demolition dust, debris, cleaning chemicals, etc. Where a large area of cleanup is
involved (more than 30 sq.ft.) a professional is usually called to establish negative air in the work area and to install containment barriers
of plastic or other material to protect cleaner areas of the building from cross-contamination during the cleanup.
If you used a building environmental specialist to inspect and define the scope of work, you should have baseline mold test samples of both the work area and other
building areas which will permit you to state definitively, at the end of the cleanup, whether or not the cleanup has caused cross-contamination
of other building areas.
The spotless cleaning produced for the second photo above was obtained by using a professional who used
media blasting to clean these surfaces. Such measures may be needed for large or complex surfaces, but quite often the
necessary steps are less technical and less onerous, as we describe next.
Clean or remove mold and moldy debris: The most succinct Mold Remediation or Mold Cleanup Guidelines one could
state would be this: the objective is not to sterilize your environment or "kill" mold, steps which are ineffective anyway - the operative words are "clean" or
"remove" problem mold and then to correct its cause.
If the total square feet of moldy material is less than 30 sq.ft. it is reasonable to handle the mold cleanup as an ordinary building cleaning or renovation procedure - hiring experts to establish negative air, dust containment, etc. is not required, but you should still take steps to minimize cross contamination in the building and to protect yourself and other occupants from moldy dust and debris.
If the total contiguous square feet of moldy material is large (more than 30 sq.ft.) then you should consult a professional to inspect the building, find all of the problem mold areas, and to prepare a mold cleanup or mold remediation plan which will guide the mold remediation company (who should be a totally independent contractor in order to avoid conflicts of interest).
The mold consultant should also advise on the steps needed to prevent future mold growth - fix the causes of mold contamination. If the mold cleanup is a costly project you should have the independent mold consultant perform a thorough visual and physical inspection of the building after the mold cleanup to assure that it was effective.
Note: some sources have amended the 30 square feet rule to 10 square feet as the size suitable for homeowner cleanup.
Remove and dispose of moldy items that cannot be effectively cleaned: Moldy drywall, paneling, trim, carpets,
boxes, junk, are removed and disposed-of as construction debris or trash, either because the item cannot be effectively cleaned, or in some cases because the cost of cleaning exceeds the value of the object. Be sure to remove building insulation that has been wet or smells moldy or has
been exposed to high levels of airborne mold. See INSULATION MOLD.
Usually moldy drywall and other debris can be disposed-of as ordinary construction debris or trash.
Scrubbing moldy surfaces - no sprays, no ozone, no sterilization:
We're talking about scrubbing here. It's the physical removal of moldy or allergenic debris that's important, not the surface sterilization.
The second we permit someone to "spray for mold" we can count on them to fail to do an adequate mold cleanup.
And if the moldy surface to be cleaned is "cleanable" so irregular or inaccessible as to make physical wiping or scrubbing impractical, you may want to consider MEDIA BLASTING for MOLD REMOVAL. The photos at the top of this page show the results of media blasting moldy wood surfaces.
What to Use to Clean Off Mold from Building Surfaces, Contents, Items
What to use to clean off mold from all of the exposed hard, cleanable surfaces: to clean off a moldy surface, you could use simple clean water, soapy water, spray cleaners, or if you prefer,
a commercial biocide (follow their directions) or a dilute bleach cleaning solution. But because so many readers have asked about specific mold "cleaning" or mold "killing" methods we list and comment on these approaches below.
At MOLD CLEANERS - WHAT TO USE we provide a detailed description of different methods people use to "clean off" or "kill" mold.
How to Use Bleach to Clean Up a Moldy Surface
Bleaching or "killing" mold is not the objective. Bleach will not kill all of the mold anyway - we can tease viable spores out of lots of "bleached mold" samples we see in the lab.
The object of mold removal is to clean the surface, to remove loose moldy material, not to try to sterilize the surface. Certain mold-contaminated materials that cannot be cleaned (drywall, carpeting, curtains) should be discarded. Clothing and bedding linens or towels can be washed or dry-cleaned.
Keep that in mind. If you want to use bleach as a cleaning agent instead of other cleaners (soap and water would work just fine) here are some mold cleanup suggestions for homeowners from the Canadian Mortgage and Housing Corporation CMHC. Please see MOLD CLEANUP with BLEACH for details of how to mix and use bleach to clean a hard surface in a building as well as warnings about where bleaching mold is a cosmetic band-aid that just won't work.
Dilute bleach with one part household bleach to four parts of clean water (do not add other cleaners to this solution as you may accidentally cause the release dangerous chlorine gas)
Ventilate the work area
Wear rubber gloves and eye protection
After physically cleaning and removing all loose mold, dirt, debris, from the surface being cleaned, let the solution stand on the surface for 10-15 minutes.
Rinse the cleaned surface thoroughly
Be sure that the cleaned surfaces are totally dry before restoring any building insulation, drywall, etc.
Discard moldy fabrics or other similar materials that cannot be surface-cleaned.
How to Deal With Other Mold-Related Problems
CAR SMELL - Mold DEODORIZING - mold in cars, campers, trucks, RVs can be caused by water leaks and can make a moldy smell problem that's hard to cure.
MEDIA BLASTING for MOLD REMOVAL - for very irregular surfaces, physical cleaning of mold can be cost-prohibitive; try media blasting
OZONE for MOLD OR ODORS - warnings about using ozone treatments to try to "kill mold" or "remove odors" - there is a place for this equipment but not as a substitute for mold cleanup and overdone it creates more problems than it solves.
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Additional technical contributors & reference sources for this article are listed below.
Canada Mortgage and Housing Corporation, CMHC, "Moisture and Air, problems and remedies, Householders Guide," NHA 5968, 1989, reprinted to 1995 cmhc-schl.gc.ca 800-668-2642. Cette publication est aussi disponible en francasi sus le tire: L'air et l'humidite - LNH 5969.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
"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
US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
Here are the Details on How to Clean Up or Remove Toxic or Allergenic Mold in buildings
How to Clean Moldy Wood Framing & Sheathing How to clean/seal mold from/on exposed lumber or plywood subfloor or roof sheathing
indoors - some suggestions based on our field and laboratory research
list of links to documents including other States: California Mold Cleanup Standards, Texas Mold Cleanup Standards, Pennsylvania Mold Cleanup Standards, EPA, CDC, and other U.S. state, federal, and world mold standards
Media Blasting: Mold Removal by Media Blasting - A test report (complete article, with illustrations) on the effectiveness of baking soda media blasting for cleaning fungal contamination in buildings, Daniel Friedman, Dennis Melandro, originally published in Indoor Environment Connections, Rockville MD, June 2003
Stuff that is not mold but is often mistaken for it - things you may not want to test. Also, not all "black mold" is toxic - here are examples of harmless black mold.
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
US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
Allergies, Allergens, Allergy Testing in buildings - References & Products
Allergen Tests in buildings advice about how to test, what to look for, in evaluating the level of dog, cat, or other animal allergens in a building
"IgG Food Allergy Testing by ELISA/EIA, What do they really tell us?" Sheryl B. Miller, MT (ASCP), PhD, Clinical Laboratory Director, Bastyr University Natural Health Clinic - ELISA testing accuracy: Here is an example of Miller's critique of ELISA
http://www.betterhealthusa.com/public/282.cfm - Townsend Letter for Doctors and Patients
The critique included in that article raises compelling questions about IgG testing assays, which prompts our interest in actually screening for the presence of high levels of particles that could carry allergens - dog dander or cat dander in the case at hand.
http://www.tldp.com/issue/174/IgG%20Food%20Allergy.html contains similar criticism in another venue but interestingly by the same author, Sheryl Miller. Sheryl Miller, MT (ASCP), PhD, is an Immunologist and Associate Professor of Basic and Medical Sciences at Bastyr University in Bothell, Washington. She is also the Laboratory Director of the Bastyr Natural Health Clinic Laboratory.
Allergens: Testing for the level of exposure to animal allergens is discussed at http://www.animalhealthchannel.com/animalallergy/diagnosis.shtml (lab animal exposure study is interesting because it involves a higher exposure level in some cases
Allergens: WebMD discusses allergy tests for humans at webmd.com/allergies/allergy-tests
Animal Allergens: Dog, Cat, and Other Animal Dander - Cleanup & Prevention Information for Asthmatics and regarding Indoor Air Quality.
Recognizing Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
Rodent control issues, including dander, fecal, and urine contamination of buildings and Building insulation are discussed at our
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) - The Atlas of Clinical Fungi is also available on CD ROM
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.
Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous.
Rot concerns in buildings-some building mold such as Meruliporia incrassata "Poria" risks serious rot and hidden structural damage
US EPA: Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
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.