How to find indoor mold contamination sources:

This document is the starting point of our mold guide that describes the essential steps needed when searching for problematic mold in buildings. This article provides an easy to understand step-by-step guide for dealing with toxic or allergenic indoor mold and other indoor contaminants: what to do about mold.

The steps in this document will be sufficient for many building owners who want to do their own mold investigation, mold testing, mold cleanup, and mold prevention in their home or office.

HOW TO FIND MOLD: How to Inspect Homes and Other buildings for Mold - the Basics of How to Find Problem Mold Indoors

Mold Testing & Cleanup Mistakes to Avoid

Much too often we are contacted by a property owner who has just paid a substantial sum to "remove black toxic mold" from a building only to learn that conditions in the property are no better, sometimes worse, than before. What went wrong with the mold cleanup project?

This is a chapter of ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD.

1. Incomplete mold cleanup projects: The owner or mold remediator was quick to address a visible mold problem without first making sure that all of the important mold reservoirs in the building had been found and listed for cleanup as needed.
   
   The result unfortunately is that another cleanup may be needed. Worse, we sometimes find people addressing the wrong mold problem in a building, for example scrubbing off cosmetic black mold that was harmless while leaving a real problem with mold-contaminated building insulation that looked "ok" to the eye.
2. In-valid mold testing: relying on a quick air test, swab, or culture to locate the problem mold or to pass a post-mold-cleanup clearance test without including a decent inspection of the premises, the remediation containment system, checks for cross contamination, etc.
   
   Sometimes this happens because the same people are providing the mold assessment, the mold cleanup, and the post-cleanup inspection and testing. These conflicting interests are risky for everyone concerned.
3. Questionable mold cleanup procedures: were followed such as inadequate dust containment, or reliance on simple biocide sprays where physical cleaning or removal of moldy materials was needed.

What does an Effective Mold Investigator Need to Know?

1. Building science: where do leaks and moisture problems occur in buildings, how do air and moisture move in a building
2. Mycology: what molds are harmful, which are cosmetic, how, when, where, and why does problem mold grow n a building
3. Industrial Hygiene or Sampling Methods: what sampling and test methods are sound and produce valid results, and which are magic and speculative.
4. Field Investigation & Mold Test Lab Experience: Where do problems occur in buildings, how do we find them, what test methods are valid, what do labs do with mold samples, what do lab results mean, how do we interpret "mold counts" or other measures of moldiness in buildings?
5. Listening & looking skills, writing skills: listen to the experience and concerns of the occupants, owners, clients; look carefully everywhere at the site. Write down mold investigation findings and recommendations that are sound, clear, and easy to follow.

Essential Steps in Screening a Building for Harmful Mold Contamination:

• If you don't see water stains don't assume there was never a flood or a leak.
• If a building has had flooding, plumbing leaks, roof leaks, A/C condensate leaks, hidden mold may be at serious levels.
• Check HVAC equipment and duct work for presence of mold or other allergens. Pay close attention to duct work downstream from air filters and blowers; check blower compartments and duct work for contamination (including dead mice), and check other areas where condensate may have accumulated in duct lines, supporting mold growth. Clean ducts in one area don't assure clean ducts everywhere; a "clean" air test does *not* guarantee no duct contamination either as variations in temperature, moisture, and mechanical disturbance can suddenly release mold spores into the building air.
• If you don't see mold don't assume a severe mold infection can't be present (behind walls, under carpets, under insulation, in HVAC equipment.) I've found serious toxic mold colonies in walls which showed no external moisture stains nor external mold growth - the clue was other evidence of a history of leaks into the subfloor, confirmed by an impaction air sampler result.
• Small changes in building conditions can themselves make huge changes in the detected level of airborne mold, from not-detected to severely contaminated. Mold may be present at problem-levels in house air depending on variations in humidity, temperature, season, air movement, and physical activity. Not finding it at a given moment is not an excuse for visual and in some cases invasive inspecting.
• A home inspection is not an environmental check for unhealthy mold or other bioaerosols or allergens. But if you see moldy conditions, or if there is evidence of a history of building leaks, plumbing backups, moisture problems, or visible mold, further more expert investigation is probably warranted.
• An industrial hygienist or mycologist may not know enough about how buildings work to complete a reliable building inspection and test. Industrial hygiene is not residential hygiene. Mycology is not building science.
• Do not be hasty to assert that a specific illness or complaint is caused by mold. The four tests (proposed by Burge, Harvard School of Public Health) are stringent beyond your means as an inspector. Mold at high levels may cause and almost certainly aggravates or contributes to a wide variety of complaints. If a significant reservoir of problematic mold is found in a building it should be removed, independent of any efforts to approve causation between the problem mold and occupant health complaints.

List of Detailed Articles on Finding Mold in buildings

If you are looking for evidence of a mold problem in a building you should review these articles.

• Mold Detection- What Mold Looks Like - Mold spores in the Home - a Photo ID Library for detection and identification of mold allergens. See:
• Mold Detection- How to Find Mold in buildings - Looking for Mold - A 'how to' photo and text primer on finding and testing for mold in buildings
• Mold Detection- Stuff that is Not Mold or is Harmless Mold - Stuff that is Not Mold but is often mistaken for it - things you may not want to test. Not all "black mold" is toxic or harmful.
• Mold Detection - using a flashlight to find mold - proper use of a flashlight can help spot mold on paneling and other building surfaces
• Lighting, proper use of: proper aiming of a good flashlight can disclose hard to see but toxic light or white mold colonies on walls.
• Mold spores in the Home - a Photo ID Library for detection and identification of mold allergens.
• How to Find and Test For Mold in buildings A 'how to' photo and text primer on finding and choosing the right spots to test for mold in buildings
• How to Find Hidden Mold in buildings - a guide for owners and inspectors, where and how to look
• Hidden Mold Photo Guide shows where to look to find hidden mold in buildings
• Stuff that is not mold but is often mistaken for it - things you may not want to test. Also, not all "black mold" is toxic - here are examples of harmless black mold.
• Simple Adhesive Tape Sampling of Moldy Surfaces - how to send a mold sample to our lab
• ENVIRONMENTAL TEST ERROR TYPES explains the classes of testing or statistical errors and how they appy to mold or other environmental inspection, testing, lab and reporting procedures. Type 1 and Type 2 errors are defined
• MOLD TESTING & SAMPLING MISTAKES gives examples of how mold testing goes wrong.

Mold Inspection Articles

• MOLD INSPECTORS & MOLD TESTERS
• MOLD INVESTIGATION PROCEDURE TIPS
• MOLD INVESTIGATION REPORTS

• Mold Investigation Tips for Home Inspectors how to find mold, where to look, what is likely to be important. Advice to building inspectors intending to inspect or test for toxic or problematic mold indoors, mold inspection methods, and mold test methods which are valid or invalid
• Mold Testing Methods - Brief Tutorial: Toxic Mold and Toxic Gas Testing Methods Compared - valid vs. invalid tests, recommendations. Lists mold testing methods and protocols, links to longer articles describing air tests for mold, surface tape or bulk mold tests, and gas testing such as MVOC's or toxic gases. Longer articles explain the shortcomings and discuss mold testing protocols.
• Mold Sampling Methods in the Indoor Environment - In-depth article: detailed critique of popular mold testing methods - Is your mold test kit worth the bother?
• Classes of Mold: what types of cosmetic, allergenic, or toxic mold are a problem? Can mold be cleaned-up successfully?
• Levels of Mold: How much toxic or allergenic mold constitutes a problem?
• What Mold and Allergens Look Like: mold identification photos to help identify mold - choosing what to sample in buildings
• Mold Sampling Methods in the Indoor Environment - In-depth article: detailed critique of popular mold testing methods - Is your mold test kit worth the bother?
• HUMIDITY CONTROL & TARGETS INDOORS What indoor humidity should we maintain in order to avoid a mold problem?
• THERMAL IMAGING MOLD SCANS - how reliable is thermography when used to find hidden mold contamination in buildings?

...

Continue reading at HARD TO SEE MOLD, SPOTTING or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• HIDDEN MOLD, HOW TO FIND
• MOLD INVESTIGATION PROCEDURE TIPS - home

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FIND MOLD, ESSENTIAL STEPS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to MOLD CONTAMINATION & REMEDIATION

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