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ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
MOLD: A COMPLETE GUIDE to TEST CLEAN PREVENT
ACCEPTABLE MOLD LEVEL
ACCURACY vs PRECISION of MEASUREMENTS
ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD
ACTIVITY of MOLD in buildings
AGE of MOLD - Old is the Mold?
AIR LEAK DETECTION TOOLS
AIR LEAK SEALING PROCEDURE
AIR POLLUTANTS, COMMON INDOOR
AIR SEALING STRATEGIES
AIR TEST FOR MOLD: ACCURACY
AIR TEST SAMPLING CASSETTE STUDY
AIRBORNE MOLD COUNT NUMBER GUIDE
AIRBORNE PARTICLE ANALYSIS METHODS
ALLERGEN TESTS for BUILDINGS
ALLERGENS in BUILDINGS, RECOGNIZING
ALLERGY & MOLD IAQ PRODUCTS
ALLERGY TESTS for PEOPLE
ALLERGY TEST ACCURACY
ANIMAL ENTRY POINTS in BUILDINGS
ASBESTOS CLEANUP COMPANIES
ASBESTOS FLOORING HAZARD REDUCTION
ASBESTOS-FREE INSULATION MATERIALS
ASBESTOS IDENTIFICATION IN BUILDINGS
ASBESTOS ROOFING / SIDING DUST
ATTORNEYS and EXPERT WITNESSES
BASEMENT MOLD WATER IMPACT
Is Bathroom Mold a Health Risk
Hidden Mold in Bathrooms
Bathroom Vanity Cabinet Mold
BROWN HAIRY BATHROOM MOLD
Mold Behind Marble Walls
Remove & Prevent Bathroom Mold
Clean off mold on tile, grout, or caulk
Renovating to Avoid Mold Growth
BIBLIOGAPHY for ENVIRONMENTAL HEALTH, MOLD, IAQ
BOD WASTEWATER TEST
BIOLOGICAL POLLUTANTS in the HOME - EPA
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 MOLD CONTAMINATION
CARPET STAIN DIAGNOSIS
CARPET & other STAIN TESTS
CARPET TEST PROCEDURE
DIRT FLOOR MOLD CONTAMINATION
MOLD CLEANUP - SAFETY WARNINGS
DIRECTORY of MOLD / ENVIRONMENTAL EXPERTS
DIRT FLOOR MOLD CONTAMINATION
Disinfecting Buildings with Bleach
DO-IT-YOURSELF MOLD CLEANUP WARNINGS
DUCT SYSTEM & DUCT DEFECTS
DUST ANALYSIS for FIBERGLASS
DUST, HVAC CONTAMINATION STUDY
DUST SAMPLING PROCEDURE
EFFLORESCENCE, Salts & White / Brown Deposits
EMERGENCY RESPONSE, IAQ, GAS, MOLD
FEAR of MOLD - MYCOPHOBIA
Fiberboard Insulation Sheathing Mold
FIBERGLASS INSULATION MOLD
FIBERGLASS PARTICLE CONTAMINATION TEST
FIND MOLD, ESSENTIAL STEPS
FIND MOLD in buildings, HOW TO
FIRE DAMAGE vs MOLD DAMAGE
FLOODS & MOLD CLEAN/PREVENT
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOODS IN BUILDINGS-mold
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
HIDDEN MOLD, HOW TO FIND
HUMIDITY CONTROL TO PREVENT MOLD
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INDOOR AIR QUALITY IMPROVEMENT GUIDE
INDOOR AIR QUALITY METHODS COMPARED
LAB PROCEDURES MICROSCOPE TECHNIQUES
LEAD POISONING HAZARDS GUIDE
Legionella Legionnaires' Disease
Legionella BACTERIA & HVAC Equipment
LIGHT, GUIDE to FORENSIC USE
LP & Natural Gas Safety Hazards
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: A COMPLETE GUIDE TO MOLD
MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD
MOLD APPEARANCE - WHAT MOLD LOOKS LIKE
MOLD CLEANERS - WHAT TO USE
MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD
MOLD CLEARANCE INSPECTIONS
MOLD COUNT NUMBER GUIDE
MOLD CONSULTANTS / INSPECTORS
MOLD CULTURE TEST KIT VALIDITY
MOLD DETECTION & INSPECTION GUIDE
MOLD or INDOOR AIR EMERGENCY RESPONSE
MOLD EXPERT, WHEN TO HIRE
MOLD LEVEL IN AIR, VALIDITY
MOLD ODORS, MUSTY SMELLS
MOLD PREVENTION GUIDE
MOLD RELATED ILLNESS GUIDE
MOLD SAFETY WARNINGS
MOLD SPRAYS, SEALANTS, PAINTS
MOLD TEST KITS
MOLD TESTING METHOD VALIDITY
MSDS Material Safety Data Sheets
MVOCs & MOLDY MUSTY ODORS
MYCOPHOBIA, STAINS MISTAKEN for MOLD
MYCOTOXIN EFFECTS of MOLD EXPOSURE
NOISE / SOUND DIAGNOSIS & CURE
ODORS & SMELLS DIAGNOSIS & CURE
ODOR DIAGNOSIS CHECKLIST, PROCEDURE
RENTERS GUIDE TO MOLD & IAQ
ROBIGUS & Wheat Rust Fungus
ROT RESISTANT LUMBER
ROT, TIMBER FRAME
ROT, TIMBER ASSESSMENT
SLIDE PREPARATION, MICROSCOPE
SMELL PATCH TEST to Track Down Odors
SOUND CONTROL in BUILDINGS
STAIN & BIODETERIORATION AGENT CATALOG
STAINS on & in BUILDINGS, CAUSES & CURES
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAIN DIAGNOSIS on BUILDING INTERIORS
STAINS on INDOOR SURFACES: PHOTO GUIDE
STAINS & Thermal Tracking
TECHNICAL & LAB PROCEDURES
TEST KITS for DUST, MOLD, PARTICLE TESTS
Thermal Expansion Cracking of Brick
THERMAL EXPANSION of HOT WATER
THERMAL EXPANSION of MATERIALS
THERMAL IMAGING, THERMOGRAPHY
THERMAL IMAGING MOLD SCANS
THERMAL MASS in BUILDINGS
THERMAL TRACKING & THERMAL BRIDGING
TRAPPED MOLD BETWEEN WOOD SURFACES
TRIM, INTERIOR INSTALLATION
TRAPPED MOLD BETWEEN WOOD SURFACES
TRUSS UPLIFT, ROOF
TRUSSES, Floor & Roof
Urea Formaldehyde Foam Insulation UFFI
URETHANE FOAM Deterioration, Outgassing
UV LIGHT BLACK LIGHT USES
VAPOR BARRIERS & CONDENSATION in BUILDINGS
VENTILATION in BUILDINGS
VINYL CHLORIDE HEALTH INFO
VINYL Siding or PLASTIC Window ODORS
Volatile Organic Compounds VOCs
WALL SIDING TRIM & FINISHES
WALL FINISHES INTERIOR
WALL CONSTRUCTION BARRIER vs CAVITY
WATER BARRIERS, EXTERIOR BUILDING
WATER ENTRY in buildings
WATER ODORS, CAUSE CURE
World Trade Center Collapse Dust Photos
Brown hairy mold in bathrooms (and on OSB subfloors): this document gives advice on identification of and health risks of brown hairy mold found in bathrooms (and other building areas), including brown hairy Stemonitis sp. mold found on bath floor tiles, under carpeting, on wood subflooring.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Here we also discuss how to address the risk of further hidden bathroom mold, and we cite references on the toxicity of Stemonitis sp. - a brown hairy myxomycete mold found on OSB, wood subfloors, and in some bathrooms such as the bath floor shown in our page top photograph. This article series 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 article series on evaluating, removing, and preventing types of mold on various bathroom surfaces begins at BATHROOM MOLD. FIND MOLD in buildings, HOW TO 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 TEST KITS for DUST, MOLD, PARTICLE TESTS for details).
Also see Brown Mold for more general questions and answers about brown mold found in buildings and an answer to "should I buy a home that has a mold problem?"
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 and also at Rental Apartment Mold Safety Advice 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 TEST KITS for DUST, MOLD, PARTICLE 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, though it is commonly described in mushroom field guides such as the National Audobon Society's Field Guide to Mushrooms 
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.
As we explain at BATHROOM MOLD, 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 or if bathroom floor carpeting has been wet (as one would expect), we suggest exploring for damaged subfloors - otherwise simply repairing the tiles or replacing moldy carpeting 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.
You will want 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, remove carpeting, or otherwise explore further for hidden mold.
See ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD on what to do about mold
We frequently add text and photos to this series of articles. See MOLD APPEARANCE - WHAT MOLD LOOKS LIKE and also to avoid spending on harmless non-mold debris see MOLD APPEARANCE - STUFF THAT IS NOT MOLD. Readers should also review Mold in Fiberglass Insulation in buildings at our The Mold Information Center - What to Do About Mold in buildings.
See Renovating to Avoid Mold Growth for specific tips that will mold-proof your bathroom, and see CONSTRUCTION DETAILS TO AVOID MOLD for a more broad list of details about mold-resistant construction in buildings.
Frequently Asked Questions (FAQs)
Questions & answers or comments about the identification, cause, & cure of brown hairy mold and other brown bathroom molds. .
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.