Teach Yourself Environmental Home Inspecting
Home SiteIndex GettingStarted Mold IndoorAir Electric Fields Contact

Tape Testing Instructions for Locating Sources of Mold Growth

Finding the sources of mold growth is important, because without knowing where mold is growing, how do you know how to clean it up and to keep it from coming back? Neither air nor ERMI/Hertsmi testing tells you where the mold growth is.

Mold growth is linked with health concerns and results in some or all of the below:

What does mold need for growth? Food and water.

Why do we work with a microscope to investigate mold growth?

What do I need to tape sample?

How do I sample?

  1. Take approximately a 3-inch piece of tape.

  2. Stick one end on your thumb and the other end on your index finger, sticky side out.

  3. Press down in the middle of the tape onto the surface you wish to sample. I press down with my index finger, positioned near the center of the tape, for more control in sampling.

  4. Feel free to press the middle of the tape down on more spots on a similar surface. We want to know if there is any mold, and if it is a lot or a little.

  5. When finished sampling, make a quarter inch tab on one end of the tape.

  6. Place the tape flat out on the OUTSIDE of a Ziploc bag, as if you were placing a Band-Aid on the bag. All you need is a mounting surface.

  7. Using the permanent marker, put a number on the tape by the tab.

    • If you cannot be exposed to permanent marker chemicals, then write the number on a little piece of paper and stick it at the end of the tape.

    • Ballpoint pen numbers on plastic can be hard to read.

    • Placing the number on the tape, rather than next to it, is a quality control measure. If the number is on the tape, the tapes can’t get mixed up.

  8. Make a list of the locations for each number.

  9. Enclose a check made out to EnviroHealth as follows:

    • $15 – 1 tape

    • $25 – 3 tapes

    • $50 – 8 tapes

    • $100 – 20 tapes

    • Over 20 tapes: $100 plus $4 per additional sample. If you later send more tapes, they, too, would be $4/sample.

  10. Mail first class to:

    • EnviroHealth
      1009 Hemlock Circle
      Manheim, PA 17545

    • Include your name, phone number, and email address.

    • If you need a rush, please call ahead to make sure accommodation can be made.

    • Do not require a signature.

Is tape sampling enough to discover a mold situation?

Tape sampling is my best tool but not my only tool. Air samples can sometimes pick up on mold conditions that tape testing misses, or underestimates. If you have health concerns, you are encouraged to also have air sampling done. If you live in my catchment area (extending out from Pennsylvania), give a buzz. Or, call a local inspector and have AGGRESSIVE samples done, i.e., stirring up dust. Also, for central air LINK***, consider sending a swab to Assured Bio Labs for DNA-level testing. If you forward a copy of the DNA results to me, I will help you interpret the findings.

Tape are one testing modality, but not the only one. I am working on a report from a recent inspection. The tape results weren’t bad, but the air samples told another story. I sample in every room, because then we can see patterns of growth/dissemination.

Since I can work with a microscope, there are no lab fees. The report would be just for the client’s information, not useful for a legal action, since a certified lab is not being used. Some samples of course could be sent off to a lab, if the inspection were for pre-purchase or some other purpose where a paper trail is needed.

Where should I sample?

Here, I will walk you through where I sampled on a recent home inspection. Hopefully this will be helpful to you in thinking through where to sample at your home.








Gauge the risk for rain water seeping into the door frame and under the sill. Use the putty knife to sample underyg and in cracks and crevices.


Concrete is not waterproof, and when walls are put up, there is risk for moisture intrusion in the wall cavity, thus raising the humidity and fostering mold growth. When folk are shopping for a healthy home, I recommend, "no finished below-grade spaces." This caution would also go for a bi-level home where the lower level is partially below-grade.

Basements were originally meant as buffer zones between the house and the ground, used as root and wine cellars and for storing canned goods. An unfinished basement is accessible for testing.

Not every finished basement has issues. There may be thick insulation in the wall cavities; the ground may be dry with good drainage; maybe the contractor knew how to finish the basement and keep the risk of mold growth low by using mold-resistant materials, such as magnesium oxide wallboard and composite base molding, etc.


A question to explore is: Does mold grow on the structure of this basement? Two tapes may be all that are needed to answer this question.



Tape-testing is limited for central air. If you can reach the AC coils, sample them. Sometimes you will see black mold growing on a supply vent cover. This typically is Cladosporium, localized at the diffuser because of condensation. Growth here is not a statement about the rest of the system.

The better way to get a clue as to what might be happening mold-wise with the central air system is to do a swab on the slits of a supply vent cover and forward that to a lab for DNA testing.

- - - - - - - - - -
Next, Understanding Lab Reports, or, back to the Mold Topic Index.


This page was last updated: July 27, 2020 11PM UTC     
Created: July 27, 2020
Viewed 239 times since July 26, 2020
(1/day over 367 days)     
Website by May Dooley     
Email: may _at_ createyourhealthyhome.com  
   Phone: 888-735-9649
Copyright 2020-2021