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. Also see When to test for mold.
Mold Testing Options
You have a choice of two mold testing options:
Do-It-Yourself Mold Testing Kits
These kits are an inexpensive method for the do-it-yourselfer who wants to determine if there is mold in their home and what type it is. This is a cost-effective way of receiving reliable laboratory analysis.
Use the mold testing kits to test every room including the attic, basement, and crawl space for elevated levels of airborne mold spores. Also test the air flow coming out of the heating/ventilating/air conditioning (HVAC) duct registers. Test at least two duct registers in different areas of your home. Many labs will accept sticky-tape samples from homeowners, and the cost of sample analysis by microscopy is usually under $100.
Use the mold testing kits anywhere there is visible mold growth inside your home. Collect a test sample from each separate infestation or growth location. You can also use Scotch tape to collect test samples of visible mold.
Hire a Certified Mold Inspector
You may feel more assured to hire a professional to do mold testing. Many mold inspectors charge as little as a $300 mold inspection fee for a very thorough physical inspection of your home to locate mold symptoms or evidence of mold infestation and of hidden water problems that can cause mold growth colonies, plus $125 for each mold test required to identify and quantify mold growth. Mold Inspectors can be found in your local Yellow Pages Directory or on the Internet.
Types of 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 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
Surface samples include:
- Lift tape samples
- Swab or wipe Samples
- Agar contact plates
These samples could be used to determine the level of contamination on a surface. 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 an indication of the types of microbial particles that have settled on the surface over time. Therefore, dust samples could give an indication of whether there is hidden mold. However, dust from carpets may also contain microbial particles brought in from outside on shoes or other items brought in from outdoors so mold testing must take these considerations into account.