Mold Testing

“What is Mold Testing? Mold can be a frustrating problem. It can be unsightly and unpleasant in small amounts but can have devastating effects in large patches or toxic species. In addition to destroying your property, toxic mold can harm your health if exposed over a long period.”


Mold Testing


Now, mold is prevalent in homes and all types of buildings. According to estimates, around 70% of homes in the US have some mold growth. However, many molds hide in places you cannot see or smell. Some molds are highly toxic and should only be cleaned with protection.


How Can You Determine Which Mold Is Growing In Your House?

The answer is to learn how to mold test. Mold testing involves collecting samples and sending them to a lab to determine the species. This service yields results different from those of mold inspections.

During an inspection, investigators are looking for physical signs of mold growth, whereas mold tests confirm the exact type of mold growing or if it exists.

DIY mold testing options are readily available in your local hardware stores.

However, inexpensive mold tests that don’t yield results waste time and money. Rather than doing the job yourself, you should hire a professional to ensure the job is performed correctly. Otherwise, you could be inhaling toxic mold without even knowing it!


Mold: What Is It?

A humid and moist environment is conducive to the growth of mold. Mold spreads through the air by emitting spores, which are microscopic particles. Floating spores hit a surface when they land. Even though mold spores are everywhere, including inside your home, it is practically impossible to remove them without installing a massive industrial clean room filtration system.

It is fortunate that mold spores only form mold if they come in contact with a moist surface. This means that keeping your home dry can help prevent mold problems from occurring. When preventing mold in your house, cleaning up spills, fixing leaks in the roof, plumbing, or HVAC system, and properly ensuring your kitchen and bathroom vent moisture is best.


Household Mold Types

Most homeowners worry about Stachybotrys Chartarum. It’s often called “toxic mold” or “black mold.” But there are thousands of species of mold. While this type of mold is relatively rare, it is one of several that can produce high levels of mycotoxins (dangerous mold-based chemicals) that can create a hazardous atmosphere in the home. Any mold can become a health risk if it grows out of hand.

Homeowners must identify mold growth in their homes, treat it, and remove it immediately. Below are some of the most commonly found types of mold in homes.



Mucormycetes fungi, such as Cunninghamella bertholletiae, Rhizomucor species, and Syncephalastrum species, are most commonly found in soil during the summer and fall. Despite their invasive nature, most people are not allergic to them.



The Alteraria alternate mold causes allergies and can enter your home from the outside. It has a dark color and velvety texture. It is essential to remove it promptly using a bleach-based cleanser once it enters your house since it can spread rapidly.



There are other places where Aspergillus lives along with the air (such as soil, compost piles, stored grains, and decaying plants). Once in a home, it can grow and spread over surfaces such as clothing, leather, or building materials, especially in humid environments.


Mold in Your House: How to Spot It

When mold grows on a window sill, for example, that could indicate the window did not seal correctly, which could lead to leaks. In many cases, the location can provide clues as to its cause.

Mold can grow undetected in several places, providing homeowners an excellent place to start looking for mold.

  • The refrigerator’s back
  • Newspaper stacks or cardboard boxes
  • In wall stud spaces containing plumbing lines behind the drywall
  • The underside of sinks
  • Around leaking windows, behind the wallboard
  • Ducts of ventilation
  • A wet carpet (flooding, carpet cleaning)
  • The backside of acoustic ceiling tiles (if roof leaks)
  • In flood-affected drywall


Mold Testing Types

Experts will collect samples from your home to confirm the presence of mold in the areas where it’s growing and verify that the mold is gone. Mold tests can identify the organisms we are dealing with and pinpoint the exact location of hidden infestations using various methods.


A Bulk Sample Test

When you notice a dark stain on your walls or floors that you suspect is mold, a Bulk Sample test is likely the best course of action. As part of a Bulk Sample, we take a small material sample (such as carpet, flooring, or drywall) for testing. Swabs or Tape Lifts are also available to collect this sample.

In this way, we can identify the mold genus. A bulk sample is usually the best, as it tests a larger sample. However, it is only sometimes practical, as you may want to avoid cutting up your carpet, floor, or wall. Swab samples tend to destroy the organism, so it is hard to identify with a microscope, while Tape Lifts are a great alternative.


The air sample

The air sample can sometimes detect and identify mold spores using a low-flow portable air pump. Collect air and compare it with outside controls.

The volume of air required depends on the particulate debris loading. A dusty environment (such as a crawl space or attic) may overload a larger sample, so a 15-30L sample is most suitable. Generally, an immaculate office would require a 75L sample, whereas a filthy office would require a larger sample.

Fast airflow tends to bounce spores off the impact plate, and results are inaccurate because spores “bounce off” the impact plate. Obtaining physical samples from dead air spaces is difficult because they exist behind walls, above ceilings, and under floors. Therefore, air samples are more common. Multiple cartridges are often gathered for this test to get a more accurate result.

In the original Environmental Relative Moldiness Index (ERMI) design, the US Environmental Protection Agency (EPA) calculated moldiness using dust samples throughout a house or building.


ERMI Tests

In ERMI tests, dust helps to determine whether mold is present in an area. DNA-based methods allow us to determine the type of mold. Many other mold inspectors often suggest this, but you should only partially rely on it.

The ERMI test involves 36 (36) different kinds of fungi, each species-specific. Molds are divided into two groups: Group I (water-damaged homes) and Group II (commonly found in all homes). Identifying the origin of mold with ERMI can be difficult, and measurement results aren’t always accurate.


Test of ARMI

It is more cost-effective than the ERMI but less thorough. The ARMI consists of 13 different fungi, and they fall into two groups: group 1 (water-damaged homes) and group 2 (frequently occurring homes).

The ARMI tests identified these fungi.

  • Chartarum Stachybotrys
  • Chaetomium globosum
  • Cladosporium sphaerospermum
  • Aspergillus Versicolor
  • Eurotium (A.) amstalodami
  • Penicillium variable
  • Aspergillus flavus
  • Aspergillus restrictus
  • Penicillium crustosum
  • Penicillium purpurogenum
  • Aspergillus fumigatus
  • Penicillium corylophilum



There are two types of mold testing, with one testing mold commonly found in water-damaged properties and one testing mold most widely found in households, such as:

  • Acremonium strictum
  • Alternaria alternate
  • Aspergillus ustus
  • Cladosporium cladosporioides v1
  • Cladosporium cladosporioides v2
  • Cladosporium herbarum
  • Epicoccum nigrum
  • Mucor & Rhizopus group
  • Penicillium chrysogenum
  • Rhizopus stolonifera

This form of testing is highly accurate, but DNA-based tests are expensive. The best way to identify specific types of mold is to let them consume different nutrition sources on an agar plate while collecting samples and observing them under a microscope.

It usually takes over two weeks to get a response to this question. While it provides highly accurate results, it is incredibly time-consuming.

Mycotoxins/poison gas Mycotoxins are neurotoxins or poison gases that harm humans. When inhaled, this gas can enter the bloodstream as a secondary metabolite of mold growth.


Mold Testing: What’s the Best Way to Do It?

A mold test and inspection will determine the following actions to remove and remediate mold in your home, office space, or property if you suspect it is present. Choosing one testing technique over another is complex – each has strengths and weaknesses. Here are some considerations when selecting a testing method:


Mold Testing: What’s the Best Way to Do It?


The Turn-Around-Time (TAT)

To be able to provide quick results, you should hire a mold testing company. They typically deliver results within five working days to account for shipping delays, lab availability, and unexpected delays. If needed, results are available within 24 hours. Fast turnaround times may incur an additional fee.


Professional vs. DIY

Various inexpensive and quick mold test kits are available for home use. Some are more reliable than others, but they require more accuracy than a professional mold test.

They are easy to contaminate or misinterpret.

You should avoid at-home testing services that don’t provide a detailed interpretation of the labs. Ultimately, at-home test services could be a better use of time and money, and we recommend booking a professional from the start instead.


Costs of Mold Tests

Depending on the type of mold testing you need, mold testing costs can vary:

  • DIY Test Kits—These range from $50 to $75, but they may not include laboratory results interpretation.
  • Genus Level Sampling—Mold testing costs $75 – $150 per sample for an experienced/competent company (the price of non-viable samples varies depending on the type of test).
  • Species-Level Testing—This is the best way to assess mold health effects for people suffering from mold symptoms, and it costs $150 to $600/sample.
  • Specialized Tests – The cost of mycotoxins/endotoxin testing, ERMI testing, and other DNA type testing varies depending on the lab, but they often require a particular kit.


Results of the Mold Test

It is critical to interpret lab results if you are not a mold expert. You will find that these lab results could be more precise, and they will not guide you on what you should do next.

To develop an effective mold management strategy, you must understand what the test results mean and how they may be deficient.


Mold Sampling Interpretation

Mold is part of the natural environment and is everywhere, indoors and out. No governmental or international standard currently defines acceptable levels of airborne concentrations of mold or mold spores in indoor environments. Without them, we would not be able to survive.

According to experts, cleaning and removing visible mold from surfaces within your home is still essential. Although non-toxic mold does not cause health issues, it can still be quite destructive to your home. Additionally, many people may experience some adverse side effects due to mold allergies.


The Normal Fungal Ecology (NFE)

Generally, we want our indoor air to be as good as the outdoor air, a phenomenon known as Normal Fungal Ecology (NFE). This method involves using an outside control sample. A comparison is made between the total spore count and the number of spores of each identified mold genus.

Those who accept an acceptable NFE will likely find spores, fungal fragments, or traces of growth that reflect a normal fungal ecology in a comparable indoor environment. It is essential to consider these factors since NFE is time- and season-dependent.


The significance of statistics

Using the Indoor Air Quality Association’s (IAQA) “Standard 2110: Level I Assessment”, “significant differences” are observed when fungal spore and structure counts exceed ten times the baseline level.


Final Considerations

Before rendering an opinion regarding the health of an environment, there are several considerations to consider. A mold sample alone is not sufficient to render a definitive opinion.

  • Inhabitants’ health
  • A visual or olfactory clue
  • History of ownership and remodeling
  • Environmental conditions at present
  • The Hydrology of the Site
  • Impacts on history
  • A component of a property transaction
  • Results of a sample survey

A mold expert can best help gather accurate samples, explain the results, and determine your next steps.