Mold Testing

When is Mold Testing Necessary?

Do you need to test your home for black mold? If there is no visible mold in any of the rooms and no detectable musty odor, and no one in your family is suffering health problems that may be mold related, then there is no reason to sample for mold. Also, mold testing is most likely unnecessary if you see a small patch of mold on a bathroom wall or on a window sill, because careful cleaning can take care of the problem.

For more details, see When to test for mold.

Mold Testing Options

You have a choice of two mold testing options:

DIY mold testing kitDo-It-Yourself Mold Testing Kits

Do-it-yourself kits are a relatively inexpensive option for homeowners to determine the kind of airborne molds they are dealing with by getting a laboratory analysis. A sample analysis should cost around $100 or less. The test kit should allow sampling from every room including crawl space or basement, attic and living areas. The  heating/ventilating/air conditioning (HVAC) system should also be tested by taking samples from at least two duct registers. The kits usually take samples on a sticky tape. You should be collecting samples from each different mold infestation location. Samples of mold can also be collected on Scotch tape.

Beware though, the EPA advises the following:

Sampling for mold should be conducted by professionals with specific experience in designing mold sampling protocols, sampling methods, and interpretation of results.

Hire a Certified Mold Inspector

Hiring a professional inspector to test for you. Certified mold inspectors may charge as low as $300 for a thorough home inspection plus $125 for each mold test required to identify and measure concentrations of mold growth. Inspectors are also trained to identify hidden moisture problems that can lead to mold infestations.

Types of Mold Tests

Air Sample Mold Tests

Air samples can be collected in two ways:

  • by impacting air on sticky surfaces for non-viable (non-culturable) analysis or
  • by impacting air on some suitable growth media for viable (culturable) analysis

Non-culturable air testing allows for determination of total fungal spores and hyphal fragments concentration since the particles are directly enumerated under a microscope. The other advantage of non-culturable analysis is that results can be obtained within a few hours after air sampling which is good for pre- and post-remediation.

The major advantage of culturable analyses is that resulting colonies of bacteria or mold can be identified to species. Read more about Air Sampling Mold Tests.

Bulk Samples

Bulk sampling involves removing a piece of contaminated material, placing it in a sterile container, and sending it to a lab for analysis. Dry samples can be sent in airtight containers, including containers made of plastic, but damp samples should not be sent sealed in plastic, because mold and bacteria can continue to proliferate in the container. Bulk samples for mold testing include pieces of building materials such as drywall, insulation material, baseboards, ceiling and floor tiles, carpets, or even dust. Bulk samples can be analysed with direct microscopic examination (DME) or culturing. In culturing, pieces of bulk sample are placed on suitable growth media and incubated.

Mold Testing with Surface Samples

mold testing with a swabSurface samples include:

  • Lift tape samples
  • Swab or wipe Samples
  • Agar contact plates

Surface samples identify the kind of mold and its concentration.  Lift tape is usually analysed by direct microscopic examination (DME). It can also be cultured. One major disadvantage with tape for mold testing is that it is not suitable on wet and uneven surfaces. Swabs and wipes can be analyzed by DME or culturing.

Mold Testing with Dust Samples

Dust samples give a good indication of hidden mold by providing a measure of mold in household microbial particles that have settled on a given surface. The dust found in carpets is not representative of overall household mold levels because particles are constantly being tracked in from the outside.