Indoor area after a mold remediation that looked good but was not successful What Characterizes of a Successful Mold Cleanup Project

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This article describes the Characteristics of a Successful Mold Cleanup Project - what should the owner or mold test consultant check?

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SUCCESSFUL MOLD TEST: How do We Define Successful Post-remediation Mold Test Laboratory Results

This article is part of ACTION GUIDE, 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 "mildew," moisture, in your house or office, building-related illness, involving your physician, treatment, sick building investigators, reduction of irritants, and special products to help clean buildings and air.

Our remediation job site photo (left) is very different from the immaculate remediation work shown at the top of this page. At left we see that a moldy crawl area was never actually entered by the remediation contractor's crew. Rather, someone stood at the crawl space entry and sprayed whatever s/he could reach from that point.

In the remediation area all moldy materials and debris should have been removed and surfaces cleaned. If we do not see those conditions, in our opinion, testing the building could be a waste of the client's money and the consultant's time as it's so likely that further cleaning is needed.

In the occupied areas of the building we should find in surface, dust, air, or other samples no more than incidental occurrence of the problem mold or allergens previously found at the property. There should be no significant presence of toxic or allergenic spores or other allergens indicating a remaining mold reservoir.

Mold cleanup jobsite photo (C) Daniel FriedmanAs one part of our post mold cleanup inspection, we tested airborne dust levels for mold at the mold remediation jobsite shown at left.

Air tests for mold after a mold cleanup job, while not a reliable overall indicator of building condition, should, if used for mold screening, show indoor mold levels at or below typical outdoor levels or at levels associated with various studies of "clean" buildings.

Warning: some investigators risk making erroneous conclusions if they attempt to compare directly levels or counts of indoor Penicillium/Aspergillus spore levels with outdoor Penicillium/Aspergillus spore levels in air samples.

With some exceptions, it is almost impossible to determine the species of these genera in an air sample. A previous report on a property I was asked to investigate showed that the indoor Penicillium/Aspergillus spore level was equal to the outdoor level and that both were at 8000 spores/M3 of air.

But a detailed investigation of the samples disclosed that the outdoor spore level was in fact a species of Penicillium while the indoor species was Aspergillus niger which, at this level I considered an indicator of incomplete cleaning traced, ultimately to incomplete demolition. In this case the original "count comparison" of indoor to outdoor Penicillium/Aspergillus spores was like comparing apples and oranges. It was nonsense.

U.S. EPA Guidance for Mold Clearance Inspection After a Mold Cleanup

As we introduced at CLEARANCE PROCEDURES, and quoting from the US EPA mold guidelines, we include this more general advice on the criteria for a mold cleanup job: [Our comments are in brackets]

How Do I Know When the Remediation or Cleanup is Finished?

  • You must have completely fixed the water or moisture problem before the cleanup or remediation can be considered finished. [See MOLD PREVENTION GUIDE]
  • You should have completed mold removal.  Visible mold and moldy odors should not be present.  Please note that mold may cause staining and cosmetic damage.  [See MOLD CLEANUP, VISUAL CHARACTERISTICS and see ACCEPTABLE MOLD LEVEL. Remember that no building is mold-free except perhaps inside of a manufacturing "clean room" - mold exists in air everywhere and small amounts of molds will be found in settled dust just about everywhere - don't set a target of "zero mold".]
  • You should have revisited the site(s) shortly after cleanup and it should show no signs of water damage or mold growth.  
  • People should have been able to occupy or re-occupy the area without health complaints or physical symptoms.  [See MOLD RELATED ILLNESS GUIDE.]
  • Ultimately, this is a judgment call [and must include an understanding of the original location, extent, type, and cause of mold contamination that was to be removed as well as the chances of other mold contamination in the building that was not addressed]; there is no easy answer. If you have concerns or questions consult our Frequently Asked Questions database and ask a question [or Contact Us directly at] if you don't find what you need.

Questions and Answers on Mold Clearance Inspections

Question: There is no visible exterior mold, the moisture levels are now fine. But interior walls are “elevated”. Does this constitute a “mold problem” if the ambient air inside the apartment is OK?

Wall test cuts to check for mold (C) Daniel Friedman

I have been reading your website as I try to educate myself on mold in homes. I am writing on behalf of my senior citizen parents, whose condo suffered a flood from a broken AC pipe in the apartment above in December of 2010.

The insurance companies really put my parents through the wringer, each blaming someone else (the unit owner above vs. the association) with my parents stuck in the middile, and after 6 weeks of being kicked out of their home because of this and getting nowhere, I finally stepped in as I felt my elderly parents were being run over.

The dry out process according to one air quality and two IICRC folks I spoke to was done substandard, so I insisted the insurance company pay for a mold inspection. The mold inspection report we now have however states that they cannot determine if the elevated mold spores they found within the walls (the ambient air was OK) were from a pre-existing condition or if it resulted from the flood.

I know the insurance company won’t budge because of course they will say it is pre-existing and not their problem. My parents are not able to pay for (or frankly, at their age, endure it at all) gutting the entire apartment to remove the drywall (which is what the report recommends).

I am mostly concerned about the risk, if any, to my parents, and my infant son who I take there to visit every day. There is no visible exterior mold, the moisture levels are now fine. But interior walls are “elevated”. Does this constitute a “mold problem” if the ambient air inside the apartment is OK? Is there anyone from your organization that can help me interpret this mold report? - M. and M.

Our mold investigation photo [above] is from a different site investigation, not the building discussed here.

Reply: "Elevated Mold Spores" in a wall, properly determined, means further, invasive inspection is probably justified

Mold test cut sample (C) Daniel Friedman

We're not sure what "elevated mold spores in the wall cavity" means without more detail. Having performed extensive tests of air and vacuum samples from wall cavities as a method to screen building walls for hidden mold, we found those methods very unreliable when the results were negative: that is, if the tests did not find mold it was no assurance that there was no problem mold inplace.

But conversely, if a test finds high levels of problem mold spores (for example Aspergillus sp. as the dominant particle other than insulation in a wall cavity sample), then further investigation is warranted.

Our photo (left) shows visible mold-suspect material on the cavity side of a drywall plug that we cut in a highly-suspect area where no mold was visible on the room side of the wall. Lab test confirmed the presence of several mold and yeast genera/species on this sample, and further investigation to determine the scope of damage was then performed.

In the case you describe, we'd want to inspect the building exterior and interior for details or conditions making leaks into the wall more or less likely so that we have an idea where to look further. We'd also want a history of building leaks and repairs. Based on that evidence we would probably decide to make one or more small 4" test openings into the most-suspect wall or ceiling cavities to look for water stains, visible mold, or other clues.

Should Insurance Companies Cover Additional Mold Discovered After the Mold Remediation Job?

The short answer to this is ... it depends. It depends on the insurance company's policies and on the insurance contract between the client and the insurer. Here are comments on my (DJF) experience with this question, based on actual cases.

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem, so we don't yet know that the possible remaining mold problem your inspector cited is the only one or even the most important one. That said, here are some things to consider regarding your question:

if the elevated mold spores they found within the walls ... were from a pre-existing condition or if it resulted from the flood

First, the fact that a mold problem now appears to be present at all it suggests that the original inspection and definition of scope of work might have been inadequate. A second possibility would be a leak and mold growth that occurred after the insured event, provided enough time has elapsed.

A pre-cleanup inspection that defined the scope of work would usually include inspection (and some limited tests) to decide where the claim-related damage is and its scope and its cause.

Properly performed, in my OPINION, and in the hands of someone with experience, that inspection is comprehensive - examining the whole building for evidence of a history of leaks, chronic moisture or water troubles, and likely areas of water damage, precisely in order to avoid the very issue that you face now - a dispute about what parts of a mold problem are related to a specific, insurance-claim-related event.

Second, in my work with several large insurance companies, we had to confront a similar problem: I sometimes found evidence that there was pre-existing mold in an area that was also covered or affected by a claim-related event. For example, I inspected a basement after a burst pipe and water flood of the basement to more than a foot of depth, soaking wall cavities, insulation,etc. I found outside conditions likely to cause water entry from roof spillage at the foundation; inside I found that the floor trim and behind it the bottom of wood paneling was rotted - evidence of recurrent water entry over quite some time. We don't get trim rot and paneling rot in just a few weeks after a single event basement flood.

I argue and the companies with whom I worked agreed (or thought up on their own) what I considered a very reasonable and certainly moral position: If the the claim-related event caused mold-producing conditions that would have been expected to wet insulation and carpeting and produce problem mold growth (in this case on basment wall cavities and probably in the finished ceiling too), then wherever that event also overapped with pre-existing damage, the overlapped area would still have been included in loss coverage by the insurer.

Conversely, if I found water damage, rot, mold in an area that was not touched by the claim-related event, that area would normally be excluded from coverage by the insurer.

Even so, my advice to the building owner was to clean and repair all of the problem areas in the same job, even if that meant that the owner had to pick up the cost for additional work that fell outside of the claim. Here are the reasons for that advice:

  • it is much less costly to have one expanded cleanup job than to have two independent clean up jobs
  • addressing only the claim-related cleanup risks that a health problem or risk remains in the building
  • addressing only the claim-related cleanup while leaving another mold reservoir in the building can prevent a succesful post mold remediation clearance inspection (depending on how well the remediator can contain and protect the remediation area from the other contaminated area)
  • in some cases the continued presence of the non-remediated mold area basically let the remediator avoid being held accountable for their own work area and for their containment procedures
  • similarly, failure to adequately identify and address sources of water entry or moisture traps that promote indoor mold means that the success of the entire cleanup job is left at risk - just hours after the cleaners leave a new leak could occur, wasting their effort.

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