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Mold testing and inspection -- What you need to know

(If you already have visible growth, you may need professional remediation. See Mold Remediation.)

Not sure if you have mold?

Many "mold inspectors" like to sell their air/surface sampling services, which are costly and in many cases is not required. It is akin to the doctor saying you need plenty of tests, which you may or may not need, but they are conveniently covered by your insurance company. Fine, except that homeowners insurance may not cover such testing. Here are some things to look out for when hiring a consultant because you think you have mold in your house or building.

#1 - Beware of "mold inspectors" who pull out their testing equipment right after they walk in the door.

Any concern you have about your house or building should be addressed by a full site inspection first. Even if you already have visible mold, any consultant should be able to render an opinion as to the actual, or at least possible, cause(s) of the mold. The findings of the site inspection should be detailed in a written report, including observations of factors that could be contributing to excessive moisture, whether from water leakage or elevated humidity. Many "mold inspectors" haven't spent the time studying building science to understand the pathways and conditions that allow mold to develop in the first place. Testing for the possible presence of mold should only be done after other efforts have proved fruitless and a hypothesis as to the cause of complaints that has been developed requires proving. Mold testing is expensive and samples should be taken only within the context of a full IAQ assessment.

#2 - A "mold inspection" does not need lab testing in many cases.

If you have a "musty smell", there is a strong possibility that there is some amplification happening in the building. Very often the problem can be addressed with recommendations resulting from a simple site inspection complemented by testing equipment, such as a moisture meter, infrared camera, and a thermohygrometer.

#3 - Beware of "mold inspectors" who say the species must be identified

Molds and fungi, like all species on our planet, are known by two names, otherwise known as binomial nomenclature. For example, people are known as Homo Sapiens. The first name refers to the genus and the first and second together, the species. A well-known and notorious species of mold, for example is called Stachybotrys Chartarum. Two basic types of mold lab testing are viable and non-viable.

Viable (culturable) vs. non-viable (countable) testing

Viable testing involves growing a sample on a petri dish, which is the only way to identify the exact species of mold. This would be akin to planting an unknown seed to see what grows. This type of testing takes a long time for results (usually between one and two weeks) and is typically more expensive than non-viable testing. In most cases, viable testing is not necessary. It should be done mainly in cases where species identification is needed for legal or medical purposes.

Non-viable tests verify presence and count of mold spores and other mold parts in the air or on a surface but do not identify the species, although in many cases the genus can be identified. Identification and counts are simply by direct observation through a microscope. Mold spores do not need to be able to grow to cause reactions in people. If you have visible growth and must spend lots of money on professional remediation, a tape-lift sample should be submitted to a lab just to make sure that what you are seeing is actually mold. There have been cases where thousands of dollars have been spent removing what was thought to be mold, but actually turned out to be something else, which was not a health concern.

So when is lab testing needed?
  • If a professional remediation will be performed, initial testing can establish a baseline with which to compare post-remediation test levels to verify that the cleanup work was done satisfactorily. Note that any remediation should never be performed until the moisture or leakage that led to the problem has been cured.

  • If, for legal or medical reasons, mold amplification must be demonstrated and/or quantified.

  • If recommendations following a full site inspection still don't solve the complaint, testing may be an option in order to prove a hypothesis.

#4 - Beware of "mold inspectors" who don't take enough samples.

Searching for mold that you can't see can be tricky. Air sampling can be useful in identifying elevated airborne spore counts. Note that air sampling is simply a snapshot of a moment in time and airborne counts can change as conditions inside and outside change. Wind, rain, snow, and fans are all things that can affect airborne counts. One sample in a complaint area has no context. There are NO established exposure levels for mold by any recognized authority. At least 3 or 4 samples must be taken to establish context. Ideally, that sampling should also be repeated at different times of the day, but in many cases, the budget is not there for repeated sampling. As an example, along with a complaint area sample, a non-complaint area sample should be taken as well as an outdoor control. Typically, indoor samples should be similar to outdoor samples. An indoor sample that is considerably higher than an outdoor sample could be indicative of mold amplification.

How we can help you

Through long-term study of building science and familiarity with the conditions and pathways that can allow mold to develop, we can provide a though evaluation of your house or building, using testing instruments, such as a moisture meter, infrared camera, and thermohygrometer, in order to determine to source(s) of the complaints, which in many cases, might not have even arisen from mold. In most cases, mold testing, which is expensive, is not required. Our service will not only help identify conditions that led to the complaint, but we also provide a written report detailing how you can take care of your property to prevent or minimize other indoor air quality issues. Every situation is unique. Give us a call so that we can discuss your particular situation to better determine how to resolve your problem.