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Here we discuss the advantages and shortcomings of using vacuum cassettes or spore traps to collect mold test samples (or other dust or particle samples) from building insulation where mold, insect, or other contamination is suspected. Our photo (page top) shows what looked like clean fiberglass insulation located over a basement that had been subject to chronic flooding and ultimately, mold contamination that was visible on other basement surfaces. Vacuum tests confirmed that the insulation contained high levels of Penicillium/Aspergillus mold spores and was acting as a mold reservoir in the building.

In this article series discuss the validity of nearly all of the popular mold testing methods currently in use, pointing out the strengths and weakness of each approach to mold sampling in the indoor environment, beginning with air sampling for airborne mold levels indoors. Because mold test validity and mold test accuracy are often confused, readers should also see ACCURACY OF VARIOUS MOLD TEST METHODS. People who need to conduct mold inspection and testing indoors should see MOLD TEST PROCEDURES and TECHNICAL & LAB PROCEDURES.

Our MOLD INFORMATION CENTER includes more broad discussions of the overall approach to building investigation, as do many expert references cited at that web. For a more comprehensive collection information about mold test methods see INDOOR AIR QUALITY METHODS COMPARED. For more on "mold classes" (Cosmetic mold vs. allergenic mold vs. toxic or pathogenic mold) see MOLD CLASSES, HAZARD LEVELS and more references such as a Mold Action Guide are at the end of this document.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Usefulness of Vacuuming exposed Building Insulation for Mold Contamination

15th Annual North Carolina/South Carolina
Environmental Information Association Technical Conference
Myrtle Beach, SC
Daniel Friedman 23 September 2005, Updated 4/14/2009

At many investigations we have found a large hidden mold reservoir in building insulation, particularly fiberglass insulation in attics under roof leaks over drywall, and in crawl spaces which have been damp or wet. We have also found very moldy fiberglass in basement ceilings after moldy surfaces and debris have been removed (such insulation should have been removed during the remediation).

Our photo (left) shows insulation that did not display visible mold but that our vacuum test found to be very mold-contaminated (see our lab photo below). (The dark stains on this fiberglass insulation were not mold but house dust deposited from air movement - see THERMAL TRACKING & THERMAL BRIDGING for details.)

Our method is to agitate the target insulation (simply poke it with your flashlight or a ruler), followed by holding our vacuum cassette an inch or two away from the insulation surface. This reliably picks up particles from the insulation without overloading the sample with fiberglass. (A baseline comparison sample collected in nearby building air before any such agitating sampling is also needed.) This method has been remarkably successful in finding and allowing the removal of several "mystery" problems in buildings where severe mold-related complaints were heard.

Any of several types of vacuum cassettes are used to collect dust from a surface. We use Air-o-Cel ™ cassettes and MCE filter cassettes. We am experimenting with vacuum cassettes loaded with high-adhesive tape. The contents of the cassette may be examined by light microscope or may be used for preparation of cultures. One special (and costly) cassette method collects dual samples permitting both direct examination and culturing.

Our lab photo (left) shows insulation that did not display visible mold to the naked eye when examined in place in the building (photo above) but that our vacuum test found to be very mold-contaminated.

This method may be used for both qualitative and quantitative analysis, depending on collection method details. It is best suited for sampling dust from surfaces and from soft goods such as carpeting or upholstered furniture. It's strength is its use in examining multiple hard surfaces with relatively low levels of debris (avoiding sample overload) or individual soft surfaces where tape may not collect particles imbedded in the surface, and in collecting dust from multiple locations in a single cassette as a building dust scan for mold.

Shortcomings of vacuuming insulation for mold

We love this method, but one must take care not to overload the sample.

If insulation is not exposed for testing one needs to make a sufficiently large opening to agitate and then vacuum the insulation - we use a 4" square opening and take care to avoid vacuuming up simply a collection of drywall dust.

See  Mold in Fiberglass Insulation for a detailed discussion of hidden mold contamination in building insulation. Also see Fiberglass Detection in Building Air.

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

MOLD TESTING METHOD VALIDITY
Introduction
  Air samples
    Shortcomings of air sampling
    Mold in Air: Quantitative Analysis
  Tape sampling for mold
    Determination of mold genera
    Determination of mold species
    Shortcomings of tape sampling
  Vacuum samples
    Surface vacuuming
    Shortcomings of surface and carpet vacuuming
    Vacuuming building cavities
    Vacuuming exposed insulation
    Shortcomings of vacuuming insulation
  Cultures to "Test for Mold"
    Shortcomings of culturing
  Swab sampling
  Shortcomings of swab sampling
  PCR methods for Mold Identification
  Mold "Testing" vs. Mold "Problem Identification"
  Are Mold Test Kits Useful?
  Reasons to Test for or Identify Mold
    1. Save Money if it's Just Cosmetic Mold
    2. Mold Related Illness
    3. Mold Cleanup Data baseline

• Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com

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