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Mold Testing For Homes: 7 Reliable Testing Methods

Mold Testing For Homes

As a homeowner, you should know how to test for mold in your house.

It’s not rocket science and is some you can learn pretty quickly.

Become familiar with the different types of mold testing methods available, because it will come in handy in the future.

Knowing this information will be beneficial so you don’t waste your time or money on testing that offers useless information about the condition of your home.

Mold is a type of fungus that needs moisture and surfaces to grow on for survival. The most common types of mold species found growing indoors include Cladosporium, Penicillium, and Aspergillus. 

When mold growth is found indoors, the source needs to be determined so it can be properly remediated.

The spores may also have been brought into the building from outside areas such as soil or vegetation. Or in some cases carried in on pets, clothing or other items.

When this occurs and the conditions are just right, then mold species will begin to grow.

This guide will provide some facts you need to know about mold testing; so that the next time you come across it in your home, you’ll be well informed!

Mold Testing Regulations

Currently, there are no federal or state regulations that indicate what levels of mold spores in the indoor air are considered acceptable. This lack of regulation makes sampling for the presence of mold very difficult and subjective.

Sampling Methods

There are varying sampling methods to detect mold species and their concentrations in an area.

However, it’s important to note that sampling for mold is not necessary in all cases.

For instance, if you can see active mold growth, there is no need to test. At this point, the right thing to do is to eliminate the source of moisture and remove the affected items.

Picture of mold growth from leak behind kitchen cabinet

If you can see it, then there is no need to conduct a sampling event.

In some instances, testing for molds can be beneficial when determining the species present or estimating the concentrations present in the indoor air.

Also, surface sampling can be used to determine the effectiveness of a mold remediation process in some cases.

These methods are frequently used to quantify and identify the various types of mold species found in the air, on settled dust, and contaminated items.

Mold Testing Methods For Homes

Air sampling for mold spores and allergens in home

Air Sampling

1. Viable Air Sampling For Mold

Viable air sampling referrers to samples that have been collected on growth media such as in a petri dish and incubated for the mold to germinate. 

This method of sampling is performed by setting up a collection device that contains a petri dish or other growth media. When the air is drawn into the device, the mold spores are impacted onto the growth media.  

When this occurs, the spores are then collected on the growth media and the sample is allowed to incubate over a specified amount of time.

After the incubation process is complete, the mold colonies are analyzed, and the genus and species are then identified. 

2. Non-Viable Air Sampling (Spore Trap)

Non-Viable air testing refers to samples that are collected using a media with a sticky surface. The spores are trapped on the collection media but not allowed to germinate.

During this process, an Air-O-Cell cassette is attached to a sampling device that draws in a specified amount of air over some time.

In some cases, the air is collected for up to 10 minutes in each location sampled. The cassette contains a slide with a sticky coating that traps spores as air is passes over the slide.

The spore trap sampling method traps mold spores, hyphal fragments, dust particles, and other airborne particles floating around in the air.

The sample is then sent to the laboratory to be analyzed. This test method will estimate the airborne particles and mold spore concentration present in the air during the sampling event.

Surface Sampling Methods

These methods are used to determine if (1) the suspected discoloration, stain, or growth observed in a location is in fact mold, and (2) to identify the species of molds growing on the surface of the materials sampled. The methods identified below require no special tools or instruments.

3. Tape lift samples

Tape lift sampling is performed using a piece of clear tape that is approximately two inches long to trap and collect suspected growth sites. You can collect this sample quickly and easily and no special tools are required.

How to Do a Mold Tape Lift Sample

Get a piece of clear tape and hold it by the ends with the adhesive placed over the suspected growth, or area you want to test.

  1. Put the tape on the area and with light hand pressure. Do not rub the tape once on the surface.
  2. Remove the tape from the surface and place it on a clean slide. If no slides are available, tape the sample to the inside of a clear zip-lock bag with the adhesive side down.
  3. When you have collected the sample, send it to the lab for an analysis.

If you would like to, you can obtain the tape lift sample slides online.

4. Swabs Test

Swab tests are used when the surface is too wet and tape lifts are not possible.  

The swab test method is relatively straight forward but the swab has to be sterile and uncontaminated. All that is required for this test is to take a swab of the suspected area or growth.

Picture of swab test to identify mold growing on surface of material
  1. Once the area is located, take the swab and gently roll the swab tip back and forth for a couple of seconds.
  2. Then place the swab back into the collection case, seal it, and send it off to the lab for analysis.  

5. Bulk Sampling

When a bulk sample is collected, a section of the suspected material is removed with the suspected growth.  One collected, the sample is packages and sent to the lab for analysis. Often, AC insulation or sections of wall board are collected as bulk simples.  Generally, about a one or two square inch piece of the material.

6. Dust Wipes

Surface testing is often used to measure how clean the area is after mold remediation activities. Suspected surfaces are wiped with a clean damp cloth.

This cloth is then cultured in a controlled environment and analyzed to determine if surface growth was present on the sampled area.

7. Micro Vac

A paper filter cassette is used to collect particles from surfaces like carpets and upholstery. The collected dust is then cultured for analysis.

While sampling for mold in the indoor air environment has some merits, it may or may not provide answers posed by individuals facing a mold-related issue.

DIY Mold Test Kits

Testing for mold in your home or indoor environment can be done with relative ease if you have the proper directions.

You are more than capable to sample the surfaces in your home.

Generally, you can collect the following samples without any specialized tools: damp wipe, air quality testing, tape lift samples on surfaces like carpets, walls, upholstered furniture, and swab samples.

While anyone with detailed instructions can collect a mold sample, the sample must be sent to a lab for the species to be identified. Most labs will attempt to summarize the results; however, some questions may still be left unanswered.

Also, the interpretation of the data and lab results may be confusing, as some individuals may not know how to read the data provided by the lab accurately.

If you want your home tested but you have reservation about doing it yourself, you have the option of hiring a professional to collect the sample and have it analyzed.

Home Tests Kits Using a Petri Dish

Some DIY mold test kits fail to add any benefit and can be misleading to individuals.

For example, the mold test kits of the petri dish variety. This sample collection method is of little benefit to you when trying to determine the concentrations of molds that may be present in your home.

Petri Dish Sample

A petri dish sample kit comes with a petri dish and an agar or nutrient-rich substrate for the mold to grow on. The agar is placed in the petri dish and allowed to set for a period to solidify.

Then the petri dish is placed on a level surface in the home for an allotted period. When the time is up, you close the lid and let the sample sit undisturbed for a couple days.

Mold spores are found all over indoors and outside, and generally causes no issues.

But by providing the petri dish with agar designed to promote mold growth, its no different from the mold spore landing on wet building materials and eventually beginning to grow.

So, is a petri dish test kit beneficial to the you? In some cases, but it provides little benefit to anyone attempting to determine the mold spore levels or other potential allergens in their indoor environment

If your aim is to identify the type of mold growing by genus and species, this test would be beneficial.

Why waste money purchasing this type of kit when one can simply swab a suspected area with a damp sterile Q-tip, perform a tape lift, or damp wipe the surface and send the sample to the lab for analysis?

These steps can yield the same results when identifying the species of mold present.

A more useful alternative would be a spore trap test performed of the indoor air for bioaerosols, mold spore concentrations, dust, pet dander, and other particles. 

While spore traps or air quality testing can be useful in some cases, it should be used in addition to a visual inspection of the home to assess if mold growth is present.

Using the air quality test alone will not provide a full picture.

Be Careful Of Unreliable Mold Testing Methods

The concept of mold testing is a complex and some methods can be subjective.

Due to the lack of governmental mold testing regulation, you must be aware of the different types of testing available for consumers and homeowners.  

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