Mold Sampling

Sampling, An Important Part of a Complete Mold Inspection

A complete mold investigation typically consists of two parts, 1) the physical investigation and 2) the collection of microbial samples (mold sampling). The physical investigation should be performed by a licensed microbial investigator who not only takes into account the visual evidence but also uses specialized moisture detection equipment in an effort to understand conditions throughout the home. Then, based on the findings of the physical inspection, microbial samples are collected and analyzed. The samples aid in determining if hidden mold sources exist, determining the extent of contamination, and definitively showing what types of molds are impacting a home.

There are many different types of microbial samples that can be collected, but the most helpful and commonly used are surface sampling, ambient air sampling and wall cavity sampling. Appropriate samples are recommended and collected based on the physical conditions found during the inspection, and are then sent to a licensed laboratory to be analyzed.

Surface Sampling

Surface sampling is useful first off to positively identify suspect materials as mold. Mold’s appearance can be similar to common household materials such as lint, dirt and staining, therefore positively identifying suspect materials is important. Additionally, surface sampling will determine the type(s) of mold that are present. For the most part, any mold growth within a home is a bad thing. However, there are certain types of molds (under certain physical conditions and when caused by certain sources of moisture) that do not require professional remediation (removal) and can be dealt with through normal housecleaning techniques. So when you consider that having a surface sample could mean the difference between spending thousands of dollars on remediation, or instead just pulling out a washcloth and getting a little dirty, a single surface sample starts to make a lot of sense. Surface samples are collected in one of three ways:

Swab Sample

Swab sample media is in simple terms a sanitary Q-Tip. It is a rod that has a cotton-like media on the end of it. The media is rolled or pushed into the suspect material and the porous nature of the media collects the suspect material. This is then placed in a sealed container with a specialized fluid inside to preserve the sample.

Tape Lift Sample

Tape lift samples are pretty much what they sound like. It is a plastic or glass clear slide that has an adhesive on one side of it. This is placed on the suspect material and it is captured in a mirror image of its natural state. This is then placed in a closed case for protection.

Bulk Sample

Bulk sampling is actually the preferred method of surface sampling, but is not always feasible. Bulk sampling is where an actual piece of the impacted material is removed and used for the analysis. It is preferred because the suspect material is undisturbed from its natural state on its growth media and as a result provides the most accurate findings. It is not always feasible though because in some cases it may mean the removal or demolition of finished building materials such as drywall or baseboards for example.