How to Find & Test for, Remove & Prevent Mold in Bathrooms InspectAPedia® -
How to evaluate the risk of toxic (or harmless) bathroom mold
Where to look for mold in bathrooms - hidden mold versus mold on bathroom tile and caulk
When is it necessary to demolish a bathroom to deal with bathroom mold?
How to renovate bathrooms to prevent future mold - details for moldproofing
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This document gives advice on how to find, test for, remove & prevent mold in bathrooms, including mold found on bath tiles, moldy tile grout, moldy caulk, and hidden bathroom mold. This article is part of our series:
FIND MOLD in buildings, HOW TO 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).
Also see BROWN HAIRY BATHROOM MOLD for a Q&A on the harmfulness of "hairy brown mold" found in a bathroom.
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.
Is Bathroom Mold a Health Risk or Indoor Air Quality Problem?
Allergenic bathroom mold: Our photo at left shows the most common place to find mold in a bathroom, on the tile grout or caulk.
Usually this mold is a member of the Cladosporium sp. group, often C. sphaerospermum - among the most common molds found, and possibly allergenic.
The total area of mold in this case is trivial and unlikely to be harmful to anyone. It is primarily a cosmetic issue. A close up of this bathroom mold on tile grout is shown at below (left).
There is no need to perform a mold test to identify small areas of mold such as those shown here. Just remove the mold and correct the conditions that contribute to mold growth. Whenever cleaning mold, especially when opening a wall or ceiling cavity where you have found leak damage, remain alert for the discovery of a large moldy area (more than 30 sq.ft.). If a large area of mold is discovered, stop work, seal off the work area, and consult a professional. See MOLD TEST REASONS for details.
Our photos above show close ups of moldy bath tile grout. Mold may also be found in bathrooms on bath caulks (page to photo) and on the surface of ceramic tiles and even toilets and sinks where those surfaces have become coated with soap scum or organic dust and debris. These molds may appear to be "black mold" but on closer look they are usually brown members of the Cladosporium family.
Hidden Mold in Bathrooms - How to Evaluate the Risk of Harmful and Hidden Bathroom Mold
A bit of looking around may disclose larger and more problematic mold contamination in bathrooms. Here are some places to look:
Look for hidden bathroom mold on the back side of wallpaper, especially above and around or near showers. Mold genera/species growing on paper surfaces such as on the back side of vinyl wallpaper or on drywall, painted or bare, are more likely to be harmful, possibly airborne species such as Aspergillus or Penicillium as well as the less easily airborne black bath mold Stachybotrys chartarum.
Look for hidden bath mold behind floor trim and in wall cavities where the floor has been wet, and in the lower portion of wall cavities where floors have been wet.
Hidden bathroom mold may be present in wall cavities around bath tub or shower controls that have leaked into the wall cavity. If your bathroom provides an access panel to the tub or shower controls from the other side of the wall, remove the panel and look for water stains there.
Bathroom mold may be hidden in the ceiling, on the ceiling side of drywall around a leaky vent fan or light fixture opening, especially over or near a shower; Bathroom moisture related mold may also be present in other ceiling or attic spaces if the bath vent fan duct has not been properly sloped and routed outdoors.
Bathroom vanity mold is often found growing on the back side or under-side of bath vanity cabinets - those un-coated surfaces pick up moisture and invite mold growth, particularly if the vanity is made of chipboard or pressboard. See our Photo Guide to Mold Under Vanity Cabinets below. Our photo (left) shows mold found under a built-in bathroom storage chest, visible only after the bottom drawer was removed to expose the wood subflooring.
Insulation mold over bathrooms: on occasion, especially where a bathroom is not well ventilated or where the occupants do not use the vent fan system (maybe it's too noisy?) we find non-visible mold in ceiling or wall insulation, especially around ceiling penetrations for lights or fans. See FIBERGLASS INSULATION MOLD for details.
Marble wall mold in baths? Mold may even be found on hidden drywall surfaces behind solid marble bath walls, as we show in our second case study of Photo Guide to Mold Behind Wall Marble below.
Mold below bathroom floor tiles? Mold may be found growing on wood subfloors under bath floor tiles or sheet vinyl flooring if the bathroom floor has been wet or flooded. If a ceramic bath tile floor has become loose we suggest exploring for damaged subfloors - otherwise simply repairing the tiles may not be a durable fix. If the bathroom is not on a basement or slab, inspect the ceiling areas below the bathroom for leak stains. Stained areas of drywall ceiling below a leaky bathroom or bath fixture usually merit further investigation.
Photo Guide to Finding Mold Under or Behind Bathroom Vanity Cabinets
If there has been protracted leakage or spillage under built-in cabinets such as bath vanities, there may be a mold cleanup job
under or behind these components.
We removed this bath vanity after receiving complaints of recurrent moldy odor in this bathroom. No amount of cleaning of other bath surfaces had reduced the mold smell. A slight slope in the bathroom floor had been sending tub spillage behind this bath vanity for a decade or more. Water spillage was inconsistent - it depended on who used the shower and how much water they splashed onto the floor.
What makes a lot of sense sense is to study the building carefully to decide on the building points at most risk
of having been wet from leaks due to construction details or other site observations. That's where one would
make a test cut. Like behind the vanity cabinet near the most moldy corner in our photo, above right.
Also see BROWN HAIRY BATHROOM MOLD for a Q&A on the harmfulness of "hairy brown mold" found in a bathroom.
Identifying & Removing Dense Brown Hairy Mold Found On Bathroom Floor & Under Carpeting
Question: what is this hairy brown mold found in my bathroom? Is brown hairy mold dangerous? How do I get rid of it?
I live in Melbourne Australia and I have a major issue with my bathroom floor. Please see my brown hairy mold photographs (below).
The images are of brown mold growths on the bathroom floor, & afterwards when I had scraped them off the floor.
I do understand that no competent expert would pretend to ID mold [or any other microscopic particle] from just a field photo.
But I have no idea what I'm dealing with and of course am concerned for my health and my family's.
Can you tell me please - is brown hairy mold dangerous?
When I scraped the protrusions off the bathroom floor, it turned into a powder & hair like structures stood on end.
I would be most grateful if you could please tell me what this could be and if it is dangerous.
I'm wanting to send a specimen away for analysis & hope that I can locate a government organisation in Australia, such as the Agricultural Department, hopefully they can do this at no cost.
- G. P., Melbourne, Australia
Reply: Examination of fungal material in an aerobiology lab is needed for sure identification of mold
Your photos are blurry and no competent expert would pretend to identify a mold genera or species just from email photos.
But with that caveat stated, the pattern and character of the mold in your photos resembles like a fungus Stemonitis sp. - see Brown Mold where we include photographs of Stemonitis sp. found on a bathroom floor and growing on oriented strand board (OSB) or "waferboard" in a basement.
Enlarging your photos [click any image to see an enlarged version] we see the mold was thick under carpeting (above left) meaning that in at least this area of the building, mold growth, including in hidden cavities such as walls, floors, ceilings, is likely to be extensive.
Watch out: And one would certainly expect other leak damage; that "wrinkled" looking floor baseboard trim board - if that's what it is in photo #1 at above left - means there have been leaks and probably rot.
If the mold test lab or aerobiology lab technician who examines a mold test sample you provide is familiar with myxomycetes, s/he should easily recognize the fungus from an actual sample. - you can use the clear adhesive tape sampling procedure at MOLD TEST KITS for DIY MOLD TESTS and send the sample to a qualified local lab of your choice [not to us].
Some Brown Hairy Molds are Probably Harmless
Stemonitis sp. is a Myxomycete ( a class of fungus) that is not listed in our MOLD ATLAS & PARTICLES INDEX nor in the authoritative Atlas of Clinical Fungi, deHoog et als. as a known toxic mold but as we warned you earlier, having so much fungal growth and leakage as we saw in that lifted-carpeting photo, you should expect that other genera/species are likely to be present even if you don't see them yourself from a superficial inspection.
Watch out for Other Leaks & Hidden Mold
Watch out: At a minimum you'd be smart to assume there are allergenic molds present and if there is more than about one square meter of moldy material, to use appropriate protection measures during cleanup as well as, of course, finding and correcting the leaks that led to these conditions.
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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
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
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)
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.
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