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ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
MOLD: A COMPLETE GUIDE to TEST CLEAN PREVENT
ACTIVITY of MOLD in BUILDINGS
AGE of MOLD - Old is the Mold?
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 / Brown 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
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
This article describes the steps that a tenant in a rental apartment or rental home can take to look for and test for hidden mold contamination, we discuss when such testing is appropriate, and we make suggestions on how to inform building management of a mold problem, what to expect the rental property managers to do if they are going to address a mold problem properly, and what the rental apartment tenant needs to watch out for during a mold investigation and mold remediation of their home.
An easy-to-print PDF version of this article is here.
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Too often we find that "black mold" on building surfaces has received attention but hard-to-see Penicillium sp. or Aspergillus sp. (for example) remain in large reservoirs on building surfaces or in insulation.
Magic bullets: Also, "bleaching mold" or "fogging" or "encapsulating" mold is never a successful remedy for a moldy building.
The places where mold is growing must be found, moldy material removed, exposed surfaces cleaned, and the causes of mold growth corrected.
If the area of mold growth is large (more than 30 sq ft) the work needs to proceed with special procedures to avoid spreading moldy dusty debris around.
The tenant or building maintenance staff may have already identified apparent mold reservoirs or sources, and of course there could be other sources from other leaks or problems they haven't discovered:
Roof leaks - can have leaked into ceilings and walls; depending on what building materials used, they could be moldy with problem molds.
HVAC systems - If there is a common A/C duct system which has become mold contaminated, no amount of cleaning in your immediate apartment would be sufficient since it is possible that the whole system needs to be cleaned, or possibly some duct sections replaced, and the cause corrected. Also it is common for A/C condensate or water from a chiller system to leak; water could have leaked into your closet ceiling and walls, also creating a problem mold reservoir.
Building insulation - often building insulation has become mold contaminated but looks "clean" to the naked eye. Few mold inspectors test this material, yet it is often discovered to be the principal problem mold reservoir in some building areas.
Very often when I visit a site I find other leaks and mold sources that need to be addressed, so I wouldn't assume these are the full extent of what needs attention.
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
Is it safe to have plastic flooring over a wood floor over a concrete slab foundation, regardless of anything else, or is the plastic flooring a moisture trap that would probably cause a mold buildup even without a flooded foundation for two months? Has anyone looked at this? At all? I looked at the Building Code of Canada, hoping it would helpfully say "Don't ever do this!!!!!" and it doesn't, alas.
My landlord put the plastic layer down about 6-7 years ago. In the bathroom (currently gutted) there was wood over concrete, and ceramic and vinyl over the wood, and the wood had rotted in multiple locations. In the kitchen there is linoleum/vinyl over wood over concrete. The floor under the sink is rotted and the boards elsewhere are warped, but the city hasn't ordered the landlord to fix it. I have no idea what's going on under the plastic in the main area because I don't know how to have a look without causing damage. I'm looking for ammunition to get the floors in the main room/kitchen officially looked at.
I can't afford to pay a consultant (on disability in Montreal) but was hoping that you could point me to something that might help. I didn't see anything on Inspectapedia but maybe don't know what to look for. If you want more details I can send you them. Thank you for all the information you do have on mold. It's been very helpful. - A.C., Montreal, 11/21/2013
I agree that this topic has not been pinned down, as I will explain in a moment. A competent onsite inspection by an expert usually finds additional clues that would permit a more accurate, complete, and authoritative answer than we can give by email alone. You will find additional depth and detail in articles at our website. That said I offer these comments: I have observed that trapped moisture within a floor structure indeed will ultimately rot the materials. All mold is everywhere all the time - it's the concentration that varies.
So all we need is a few mold spores of wood rotting fungus to have been present when a floor, perhaps dry at the time, was enclosed and sealed such that later water entry from below initiates mold growth and rot. But still, I have inspected a number of floor structures built on concrete that were sealed from above and later disassembled to show no rot damage.
The key variable, as you pose, is leaks and water entry. In short, if the building does not leak from above or up from below through the foundation or slab, the enclosed floor cavity, say sleepers on concrete, topped with perhaps subflooring, finish flooring, and tile or laminate or vinyl sheet flooring, survives quite well.
If the same floor structure cavity is wet from any source and is not opened and dried promptly mold growth and later rot can be expected to develop.
I believe that the codes are silent on this point because of the variables involved and the anticipation that good building design and proper maintenance is not supposed to tolerate water entry up through the floor of an occupied space. In other words, build and maintain your building to keep water out.
That approach is probably more cost-effective and easier to specify than to try to make every single indoor component able to withstand flooding. To be clear, we could just as well say don't ever enclose a wall or ceiling, because water can get in and cause trouble.
But we do enclose them. (And water does leak in and cause trouble.) Moving on to the specific case you describe, re: "The floor under the sink is rotted and the boards elsewhere are warped, but the city hasn't ordered the landlord to fix it." suggests to me that
- there are building leaks that need to be corrected, and that are causing costly damage to the building
- If typical building materials used such as drywall & fiberglass insulation are being wet, there is a reasonable risk of problematic mold contamination indoors too.
Please take a look at the article series I've written specifically for people in your situation, beginning at RENTERS & TENANTS: MOLD ADVICE and let me know if questions remain after you've seen that material.
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