Using a borescope to check a wall cavity for visible moldMold Testing vs Mold Inspection
What's the difference & why is it very important?

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Mold testing compared with mold inspection: this article explains why mold testing may be very unreliable and why you may need an expert on-site inspection.

Not every mold problem merits testing and onsite expert inspection or cleanup, but where large areas of mold are present, where there are serious health concerns, or where large costs may be involved, you need an expert on site, not a "mold test". Here we explain why.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Mold or Particle Contamination Tests vs Mold Inspections - why the difference is very important

Extremen mold contamination indoors (C) Daniel FriedmanNot every mold worry merits a costly onsite investigation. But failing to hire an expert when one is needed can itself be a costly mistake.

If your ONLY concern is the identity of the mold you've already seen, and if you are confident that there is not a possible problem elsewhere on the property, you could simply send a mold sample to our lab (or to any mold lab) for determination. Instructions for an inexpensive and easy way to test mold or to screen settled dust for mold are at MOLD TEST KITS.

We emphasize that for small areas of mold contamination, generally where less than 30 square feet of contiguous mold is present, simple building cleaning and renovation procedures are all that's needed and testing is usually not appropriate. Most building mold contamination falls in this first category.

At DO IT YOURSELF MOLD CLEANUP we provide suggestions for a do-it-yourself cleanup of small areas of mold.

At MOLD TEST REASONS we discuss when it is appropriate to test for mold.

A mold professional may have some neat gadgets to find or test for mold, but a true building expert knows that a thorough building inspection and an understanding of how buildings work and where they leak, as well as an understanding of mold itself, are critical in finding hidden mold problems and in specifying the cleanup work needed.

To be effective and to produce advice which is based on more than a wild guess, building investigations for mold, allergens, gases, or other indoor air quality concerns must take a broad approach to site and building examination for probable sources of moisture, bioaerosols, toxic/allergenic mold, or other allergens.

In order to have some confidence that we understand the building, how it works, where the risks and problems lie, we examine at the entire structure, inside and out, and its mechanical systems are examined as well. Partial inspections, like partial remediation, risk the cost of having to repeat the process if it was not proper and complete the first time.

In the photos above on this page, though not much mold is visible on the drywall, the presence of fungal fruiting bodies or "mushrooms" growing indoors at the wall baseboard trim tells us that this building was very wet for some time - professional inspection is needed to define the location and extent of moldy material removal and cleaning.

Reader Question: where can I buy a bariscope? I want to check for hidden mold.

Where can I get a bariscope in Toronto?

It is a boriscope.

Reply: you mean borescope. But your approach to checking for hidden mold may not be effective.

Sorry, there is no such device as bariscope. Nor a boriscope. Perhaps you are asking about a borescope such as the instrument we discuss at Hidden Mold in Wall Cavities ? If so, any professional inspection equipment supplier in Toronto or online can quickly provide the instrument.

Reader follow-up: I'm hiring a mold inspector

Thank you, an inspector is coming tomorrow at 7pm...he tried to cancel...i iinsisted as i  im leaving the unit by sunday, i settled in a human rights tribunal with the illegal landlord, for illegal profiting, they were refusing to accommodate me in regards to mold testing, public health inspector and management there, said there were no visible signs and would not make a demand for the landlord to pay as the recent agreement i had made where they would pay, hence the public health human rights claim.   

Reply: Reliance on a borescope alone for hidden mold detection is unreliable.

For hidden mold investigation, a borescope alone is inadequate. While I find the borescope useful for a limited view into tight spaces, experiments with the results of inserting the scope into a building wall or ceiling cavity compared with the improved view afforded by cutting a larger inspection opening (typically 4" x 3") has convinced me that it's worth the trouble of making the larger opening size at strategically-chosen high-risk locations.

Furthermore, making the larger wall or ceiling cavity opening makes several more reliable inspection steps possible when checking for hidden mold:

Reader Follow-Up: why can't I just scrape a surface and take it to a lab?

What if i scrape and take it to a lab;

Reply: Why you need a proper, more-reliable investigation for hidden mold or other particulate contamination

Mold contaminated apartment ceiling (C) D Friedman and SMScrape tests of surfaces risk damaging the material; for surface testing use the tape method described at MOLD TEST KITS.

But you miss my point: "hidden" mold might be suggested by the detection of certain mold material in a dust or surface sample from a building interior, but that approach alone is invalid and unreliable; absence of evidence is not evidence of absence of a problem. It may simply mean that the "test" was not properly conducted or that the sample was not collected from a location that would have given evidence.

If extensive mold contamination is visible on indoor surfaces, you do not need to hire an investigator or "mold test consultant" to prove that fact. Our photo at left shows more than 30 square feet of contiguous mold growing on a drywall-covered ceiling in a building.

However, you might need to hire an expert to determine the extent of mold remediation needed and its cause: in other words to prepare a mold remediation plan that should guide the initial efforts of a separate mold remediation or cleanup company.

But where a large, problematic hidden mold reservoir is suspected but there is not obvious visible mold in the building occupied spaces, an inspection, not just a "mold test" may be in order.

Our article series beginning at MOLD / ENVIRONMENTAL EXPERT, HIRE ? helps determine when such an expert is needed. Here I summarize the components of a more thorough, reliable inspection for hidden mold contamination.

Scope of Inspection for Hidden Mold

A competent inspection and test for hidden mold contamination requires an expert inspection of the entire structure, beginning outdoors and continuing inside. The inspector must know building science, building methods and materials, mycology, as well as the science of various inspection and test methods.

In that combination the expert can form a reasonable opinion about the building construction methods, history of leaks or floods, ventilation and moisture concerns, and thus areas of greatest risk of presence of a hidden problematic mold reservoir.

Decision to Use Invasive Inspection Methods: test cuts into building cavities

Armed with that information, limited invasive inspection, best by making modest test openings into building cavities to inspect the inner cavity surfaces and (if present) insulation, confirm the presence or absence of mold contamination in the most at-risk areas.

Reasonable Estimates of Hidden Mold Risk Level

Such an approach does not guarantee that there is not a hidden  mold problem elsewhere, but it does permit the investigator to make statements about reasonable levels of risk, extent of investigation conducted, the chances of other hidden mold reservoirs not yet found, and thus the approach permits a rational decision about how far to take the investigation.

Risk of Wasting Time, Money, Health if Relying on Inadequate Mold Investigation Methods or Tests

By a rational approach to hidden mold investigation and testing can one avoid the waste of time and money and the very high risk of incorrect results that accrue from less thoughtful and less thorough "mold tests"

Where the potential costs of an unreliable mold inspection, test, or investigation include possible health risks to building occupants and economic risks of facing a still more costly mold remediation job, relying on a simple "test" is, in my opinion, foolish.

The Usefulness of Mold Tests

This does not mean there is no place for testing, but rather that tests for mold or other environmental contaminants must be conducted using reasonable science and experience, and their results understood accordingly. 

Even  should a more general "test" for mold, say an air test, suggest that a problem is present in the building, that information, without an intelligently drawn idea of where to look further, is of little value. We  don't know much more than we did before.

Summary of Proper Mold Investigation: Six questions that must be asked and answered

In sum, any building environmental investigation procedure, to be worth its salt, or worth the fee, must provide actionable information. It must answer the questions:

  1. Is there evidence of a problem that merits further attention?
  2. Is there evidence of a likely hidden problem that merits further attention?
  3. Where are hidden problems most likely to reside?
  4. What evidence has been found in those locations to argue for or against an actionablecontamination?
  5. And finally, if no evidence of mold contamination has yet been found, when and how do we reach a conclusion that it is time to stop spending time and money looking for a problem?
  6. When have we found a problem, what is the extent of the problem, where is it located? what extent of cleanup is needed, and what problem causes can be identified and corrected to prevent a recurrence?

Key Mold Emergency Articles


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