When to Test for Mold

Mold testing is becoming an issue in real estate transactions. Some buyers and inspectors think that mold testing should be a regular part of prepurchase home inspections, just as radon testing and pest inspections are.


When to test for mold: is testing reliable?

We do not believe that mold testing should be required in a prepurchase home inspection, for a number of reasons. First, mold test results can be very confusing and thus may not be particularly useful. Second, mold, unlike asbestos and lead paint, is a living organism and may not be present at the time of the inspection but then could start to grow and spread within days, if conditions are right. Third, there may be mold growth in rugs or furniture that will move out with the seller. And finally, the conditions under which an air sample is taken during the mold inspection can have a big impact on the results.

For example, if all the windows are open, most of the spores found in the house air will probably be from the outdoors. If someone in the house recently threw out a moldy cantaloupe, spores from the fruit could be in the air. Airborne mold spores could even have come from the clothing of a termite inspector who checked out a moldy crawl space and then entered the house to speak to the buyer.

The American Conference of Governmental Industrial Hygienists (ACGIH) advises that:

The primary emphasis on indoor mould assessments should rest with a thorough visual inspection of the property.

When to test for mold - illustration with stethoscope

It is much more valuable to have experienced mold inspectors provide the information you need to prevent the conditions that can lead to mold growth than to have a fuzzy growth on a wall sampled. Chances are it’s mold. Many home inspectors own moisture meters, which can help identify surfaces that have elevated moisture content, conducive to mold growth. The important questions are: Why is the mold there? What is the best mold removal and how do you keep it from coming back?

If people are sick in an indoor environment and suspect that mold may be a cause, then mold testing can be useful in determining whether mold spores are in fact present. But a thorough visual inspection at the property prior to testing is still the vital first step.