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Mold & Real Estate Transactions

What are the testing options available to anyone concerned about mold during a real estate transaction?

Mold is a real concern for all of us.  Whether you rent or own, mold can affect your health, the structural integrity of the building materials, and more.  In our last post, Mold, Moisture, and Your Home, we discussed the main concerns with mold.  In this post, we are going to look at the main types of testing available during a real estate transaction. Safe Home Environmental has two ways to test for mold.  When there is “apparent” mold we will use direct sampling methods.  When there is no “apparent” mold we will use the air sampling method.
Mold under kitchen sink

Direct Sampling is performed when “apparent” mold is seen during an inspection.  The places where an inspector may typically see “apparent” mold are the bathroom, kitchen, laundry room, crawlspace, and attic. Any room that has appliances that use water or where moisture can build up.

There are several ways to take a direct sample.  There are bio-strips, swab samples, bio-tapes, and more.  Regardless of the sampling medium, the process is the same.  All samples are sterile and housed in a protective package.  Labeling is important to ensure that you know which sample goes with which area being sampled.  Typically the date and a sampling # are written on the sample along with the address.  It is a good procedure to also take a picture of the place sampled.  The samples are recorded on the chain of custody form that gets mailed to the lab along with the samples.

In the pic below, you will see two samples that I took at a property in a tight attic space.  The long tube holds a swab sample.  The rectangular case holds a bio-lift tape sample.  Both of these samples were taken in an attic space where moisture was finding its way back into the attic creating a problem.  You can see the impact of the moisture in the last pic.  The insulation baffle is deteriorated and detached from the truss.  There is a dark stain coloration forming on the sheeting and truss.

I started with the bio-lift tape but due to the limited space, I couldn’t get as close as I liked with the bio-lift tape.  The swab sample is a longer sampling device which allowed me to take a sample from an area that showed more “apparent” mold.  As it turns out both samples came back positive for mold growth.

The middle picture is the paperwork needed to travel along with the samples to the lab.  The form is called a chain of custody form and must always be sent along with the samples.  As the samples change hands the chain of custody form is updated by each individual who handles the samples directly.

These samples will be analyzed by the lab and return their analysis within 24 hrs of receiving the sample.  In most cases, we can have the results in 2 – 3 days.

Direct samples of mold
Chain of Custody
Mold in attic space

Indirect sampling or taking mold air samples is performed when there do not appear to be any obvious areas to take a direct contact sample.  Since there is always mold found outdoors we can sample the mold just outside the home and use this as the point of reference to see if there is also a mold issue in the home.

Prolab 15 Air cassette for mold testing

Mold air sampling is done using an air pump set up at 15 liter/min.  Attached to the air pump is a mold air-o-cell cassette like the one to the left.  This cassette holds a micro slide with a tacky surface that will capture mold as the air is pulled past the slide.

A typical time of 10 minutes is set so the slide is exposed to 150 liters of air.  The slide will collect mold and other debris.  The outdoor sample becomes the standard to judge the two indoor samples.

There are two things that could indicate a mold issue inside the home.  If the raw spore count inside the home is an order of magnitude or higher than that of the outside, this would indicate a mold issue.  If the types of spores found inside the home are not found outside the home and they are of the type that would otherwise not be there without a growing mold issue, this would indicate a mold issue.

The lab will send their report containing the analysis of the samples that they received, regardless of how the sample was taken.  In the next mold post, we will look at a typical lab report and walk you through how to read it.


Committed to Your Safety and Peace of Mind – Jennifer Thorne Testing Services Manager  | IAC2 Certified for Mold & Radon | NRPP Certified: 113525-RMP, 113629-RMS | DEQ Meth Certified: MCP-0146-C