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How to Test Your Home for Mold

woman on her phone while holding a pan to catch water from a leak in her ceiling

Testing your home for mold involves a science-based inspection using environmental and surface testing for mold and mycotoxins. In this article, we’ll explain how mold exposure happens and how to test your home if you suspect issues. This is part one of a two-part series about safe, science-based mold testing and remediation. Please read our article about mold remediation to learn how to safely remove mold from your home.

How Does Mold Grow?

We're all familiar with the sort of mold that grows when leftovers sit in the refrigerator too long. We also benefit from helpful mold when we make aged or fermented foods like bleu cheese. But toxic mold is a different story altogether, and exposure to these harmful fungi can cause serious, life-threatening illness.

Much like humans, mold requires two things to grow: food and water. Combine moisture from humidity or a leak with common building materials such as drywall, wood, or paper, and you've got all the nourishment needed for toxic mold. The real surprise comes with how often your environment has the components needed for mold to thrive!

Where Does Mold Exposure Happen?

Research by the U.S. Environmental Protection Agency found that 85% of commercial buildings had evidence of water intrusion, and 43% had current water intrusion at the time of the study. [1] That's right: As you read this, almost all office buildings, medical facilities, schools, stores, and places of worship have the right environment for mold growth.

The issue crops up closer to home as well. Based on 2009 government census data, about 10% of homes had water leakage from an external source, and about 1% had leakage from an internal source. [2] Based on weighted population averages from multiple studies, it is estimated that about 50% of homes have some degree of dampness.

Remember that, unless homeschooled, your child also spends a significant period of time in a separate school building every year. Schools, like all government buildings, are often made by the company with the cheapest construction bid. As such, leaks are common. In fact, the U.S. Government Accounting Office found that about 30% of U.S. schools tested had plumbing problems, and 27% had roof problems. [3] Other studies have suggested that mold may be as common in schools as it is in U.S. homes. [4]

It is very difficult (if not impossible) to get schools to test for mold or mycotoxins, which means you must resort to watching for symptoms of mold toxicity instead. Document changes in your child when they stay in different places for an extended period of time. Clues might be changes you see during and after holiday or summer breaks - if your child deteriorates after starting school again, mold may be present in the school. Often the onset of PANS/PANDAS occurs following a trip for Spring Break because many coastal locations have very high humidity at baseline, and mold growth is extremely common in vacation homes.

If you think your home or office may be one of those buildings that has a current or past water exposure, then it's vital that you perform proper testing to ensure the safety of everyone who enters.

How Do I Test My Home for Mold?

The first step in evaluating your home for possible mold is assessing the risk. It is important to remember that mold is not only present in older homes. Building materials like drywall and lumber are often exposed to humidity both before and during the building process. This can increase the chance of mold growth in a newly built home.

A known water leak (from a leaky pipe, broken sump pump, overflowing bathtub, or roof leak) always increases the risk of mold and mycotoxins, unless the affected area was immediately exposed and aggressively dried within 24 hours of the leak.

In addition to a known water leak, your nose can also sniff out a mold problem. Mycotoxins are odorless but volatile organic compounds (VOCs) produced by mold are not. Mycotoxins are responsible for creating the musty odor often associated with mold, so a musty odor is a definite cause for concern! However, it's important to note that the lack of an odor does not necessarily rule out mold. Any home that has had a significant leak (especially if not found for more than 24 hours) should be checked for mold and mycotoxins.

Humidity in the air and on surfaces can also indicate an increased risk for mold. The humidity level in your home is quickly and easily tested with an inexpensive hygrometer. Hygrometers are also available, which have prongs that can be inserted into drywall or wooden surfaces to indicate humidity.

If you think there is a risk of mold in your home, or if you are ill or you have mycotoxins in your system, a professional mold inspection is recommended.

mold inspector with a clipboard

How Do I Find a Mold Inspector?

In many states, no specific certification or qualification is required for an expert to test or remediate mold in your home. That's why it's important to use a source you can trust when choosing a professional mold inspector, also called an Indoor Environmental Professional (IEP).

We cannot overstate the importance of choosing a qualified IEP for your mold testing and remediation. We have had patients get sicker after they tried to remediate on their own or hire someone who promises to do the whole job for a much lower price than the experts.

In order to help facilitate your search, The Center for Fully Functional Health is a founding member of the International Society for Environmentally Acquired Illness (ISEAI). This worldwide professional organization is dedicated to the treatment of chronic infections, mycotoxins, and other environmental toxicants and their effects. The ISEAI website is always our first recommendation when looking for an IEP in your area. We are also happy to provide guidance for our local Carmel, Indiana, patients about which local IEPs are the best choice and which should be avoided.

If the ISEAI website does not feature a professional who works in your geographical region, we recommend looking for a professional certified by the American Council for Accredited Certification with both CIEC and CMC certifications. This means your IEP is a Council-Certified Indoor Environmental Consultant and a Council-Certified Microbial Consultant with at least eight years of experience.

If you need to progress to mold remediation, look for ACAC candidates with CMRS or CMR certifications. A CMRS certification means the IEP is a Council-Certified Microbial Remediation Supervisor with at least eight years of experience, while a CMR indicates a Council-Certified Microbial Remediator with at least two years of experience.

What Should a Mold Inspection Look Like?

Based upon years of experience and many encounters with patients who have become ill after mold exposure, we recommend an in-person inspection as the very first step.

Visual Inspection

The inspector should look first at the landscape outside the home and make sure it is not graded toward the home, which can result in water in the basement or crawlspace. The IEP should also inspect the roof and attic, as well as the basement and any crawlspaces present. This portion of the inspection should be hands-on, and the IEP should physically enter all of those spaces.

They will be looking for any signs of water intrusion (staining on the ceiling, for example) and for mold itself. Humidity should be checked with a high-quality hygrometer, and good inspectors also use a temperature gun to check for thermal cold spots on the walls of the home. Cold spots may indicate cracks or water behind the wall.

Spore Trap & Tape Testing

Next, the inspector may suggest spore trap testing for molds. This should be done both inside and outside the home. Spore counts inside the home should be at least 50% lower than outside the home. One issue with spore traps is that not all molds are airborne, and molds such as Stachybotrys are more problematic than other molds. Some molds are more “sticky” and tend to be settled and therefore underreported on spore traps.

Tape testing is also often performed by IEPs to determine whether residue in building materials is mold, and if so, what type. This can be helpful in some cases.

A word about doing your own mold testing: There are some direct-to-consumer mold testing plates that may be set up in the home, but these are not standardized in terms of results. In our own practice, we have unfortunately seen these consumer tests read normal in homes with significant mold issues. We've also had patients get an abnormal number indicating a high mold count, only to have extensive IEP evaluations fail to find mold. These consumer tests can be a starting point, but they do not replace professional mold testing.

Environmental Mycotoxin Tests

As noted above, the major issue with mold exposures comes from the mycotoxins they produce. Realtime Labs offers an environmental mycotoxin test that measures four major families of mycotoxins. Samples are taken from the air handler filter in your home or via swab from inside the furnace ducts, then tested for these mycotoxins.

If a home has no evidence of visible mold, a positive environmental mycotoxin test may indicate hidden mold, past mold which was remediated, or mycotoxins which have been transferred on belongings from another location. Since the samples are taken from the air handler filter, a positive result means that these mycotoxins can be blown into any room in the house via the vents. This test can also be matched up with tests from you or your child. If similar mycotoxins are noted, the home may be the source.

air vents near the ceiling

Don't Forget Actinomyces

It is not just mold and its associated mycotoxins or VOCs that make people sick in water-damaged buildings. We are now aware of specific bacteria common in the same settings.

One specific bacteria that can make people sick is called “actinomyces,” or sometimes “actinomycetes.” These bacteria can cause human infections of the lungs, sinuses, and other areas. [5] [6]

Actinomyces was once thought to be a fungus, and it behaves in some ways as a fungus. This bacteria may produce biotoxins which adversely affect human health, similar to mycotoxins. One report discusses the possible role of actinomyces as a trigger for rheumatoid arthritis. [7] Actinomyces also stimulate inflammation and oxidative stress. [8] 

Testing for actinomyces DNA is available from a company called EnviroBiomics. Some IEPs and medical practitioners even believe that testing for actinomyces is actually more important than mold in buildings with leaks or significant humidity. If you suspect illness because of exposure to a water-damaged structure, remember actinomyces testing as well.

What to Do If You Find Mold

If your IEP finds evidence of mold or mycotoxins in your home, then professional remediation is a must. This process involves repairing and replacing any structural materials affected by mold, as well as cleaning or disposing of household belongings that have been affected. It is important that you do NOT attempt mold remediation without the advice and oversight of a qualified IEP, as improper remediation can actually worsen mold growth and related health issues.

If you suspect that you or your loved ones are suffering from mold toxicity, and you are able to travel to The Center for Fully Functional Health in Carmel, Indiana, please contact our functional medicine office immediately by filling out the form at the bottom of this page or calling (317) 989-8463, Monday - Thursday 8AM to 5PM Eastern. Our physicians have decades of experience successfully treating mold toxicity and related disorders, and we would be honored to guide your recovery.


  1. Burton LE, Baker B, Hanson D, Baseline Information on 100 Randomly Selected Office Buildings in the United States (BASE): Gross Building Characteristics. Proceedings of Healthy Buildings. 2000;1:151-156
  2., accessed 4/11/2022
  3., accessed 4/11/2022
  4. Mudarri D, and Fisk WJ. Public health and economic impact of dampness and mold. Indoor Air. 2007;17:226-235
  5. Park JH, Cox-Ganser JM, White SK, et al. Bacteria in a water-damaged building: associations of actinomycetes and non-tuberculous mycobacteria with respiratory health in occupants. Indoor Air. 2017;27(1):24-33
  6. Gajdács M, Urbán E. The Pathogenic Role of Actinomyces spp. and Related Organisms in Genitourinary Infections: Discoveries in the New, Modern Diagnostic Era. Antibiotics (Basel). 2020;9(8):1-19
  7. Lorenz W, Trautmann C, Kroppenstedt RM, et al. Actinomycetes in Moist Houses, The Causative Agent of Rheumatoid Symptoms? Proceedings: Indoor Air; 2002:58-63
  8. Hirvonen MR, Ruotsolainen M, Savolainen K, Nevalainen A. Effect of viability of actinomycete spores on their ability to stimulate production of nitric oxide and reactive oxygen species in RAW 264.7 macrophages. Toxicology. 1997;124:105–114

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