Mold Testing 101

By: Beth Krietsch

Every home contains at least a bit of mold. You’ll find it growing in bathrooms, basements, laundry rooms, or other humid and damp spaces in your home where mold most commonly occurs. Yet mold can also be hidden out of sight, like under carpet, in crawl spaces, behind walls, in ventilation ducts, above ceiling tiles, and on or behind wallpaper.

When the presence of mold is obvious, you won’t need to call someone to conduct mold testing. However, identifying hidden mold requires  professional help. We’ll guide you through everything you need to know about mold testing 101.

How do I know when mold testing is necessary?

Testing or sampling for mold will help you discover possible sources of the mold, know what type(s) of mold are present, and determine whether a suspected contaminant is mold rather than dirt or soot.

Here are a few scenarios when mold testing is a good idea:

  • You detect the smell of mold, but you’re unsure where it’s located.
  • You’re experiencing health issues without any other explanation. This could manifest as difficulty breathing, frequent coughing, sneezing, or a general unwell feeling.
  • A property is being sold or purchased.
  • You’ve recently been dealing with leaks or other plumbing issues and believe mold may be present.
  • You want to determine if a prior mold problem has been sufficiently addressed.

Will a home mold testing kit be sufficient?

A home testing kit won’t usually get the job done. It may be able to tell you that mold is present, but it probably won’t reveal where or how much. It’s better to call in a trained professional who knows what they’re looking for and how to resolve the issue to ensure your home is mold free as soon as possible.

How do I find a professional to do the mold testing?

You want to find a professional who is experienced in sampling mold and interpreting results. These trained professionals follow guidelines set by professional organizations such as the American Industrial Hygiene Association (AIHA).

You can find someone by searching online or seeking out recommendations from local friends and neighbors. Always check for professional references and prior experience locating and identifying mold growth before hiring a professional.

What should I expect with a mold test?

The person you hire to test your home for mold will carry out a visual inspection and possibly a mold sampling. Sight and scent will be important tools to the inspector, but they may also use a flashlight, borescope (an optical probe that checks for mold by inserting into a small hole in the wall), a moisture meter, and clear plastic tape. The mold tester may wear protective equipment to avoid breathing in mold and mold spores and protect the skin and eyes.

The inspector will usually perform air testing, surface testing, water testing, and bulk testing where they look at insulation, carpet, walls, and other materials in the home. Then the results will need to be analyzed according to standards set by an organization such as AIHA or the American Conference of Governmental Industrial Hygienists (ACGIH). After testing is complete, the inspector will usually provide a report for mold removal.

How much does mold testing cost?

In general, mold testing costs around $300–$600. Pricing for mold testing will vary depending on the size of the problem. Most companies and inspectors will be able to provide an estimate after an initial visit or interviewing you about your home and the potential mold problem you’re dealing with.

How to minimize mold growth

The goal with any mold remediation is to address the underlying cause of the mold, not just remove mold from your house. So once you’ve cleaned up the mold, you’re not necessarily done with the problem.

The most important step in eliminating mold growth is to minimize moisture. Without moisture, mold can’t grow. That’s why it’s critical to identify the water source causing or contributing to mold growth. To control moisture in your home, consider:

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