Mold contamination © D Friedman at Mold Test Preparation: Clean Up First?
What to Do Before Having a Mold Contamination Inspection or Test

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Mold test procedures: pre-cleaning. this article explains why it is best to leave moldy building surfaces alone if you are about to bring in a professional for building inspection and testing as a screen for contamination.

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Should You Clean Mold in Advance if You ARE Going to Hire a Mold Expert

If you are thinking of hiring a professional to inspect, diagnose, and test your building for mold or other problems we prefer that you do NOT conduct a "do it yourself" cleanup ahead of time. Cleaning up the mold that you see does not preclude an expert's ability to find areas of suspicion or even to find mold, but

  1. Cleaning up the mold you see may remove some easy-to-identify materials that are useful to compare with what we find in other screening measurements find in the building - that is, it's useful to know some apparent sources of particles that we may later find in screening samples in the building.
  2. Contamination risk: Cleaning up a large area of mold risks cross-contamination of other areas in the building
  3. Illness risk: Doing a large mold cleanup without taking proper precautions could make someone sick by stirring up airborne debris and thus increasing the hazard in the building.

Rather, if you already believe that a mold emergency is present, rather than performing amateur cleaning before mold testing, you should probably not be in the building.


Can You Clean Up Small Areas of Mold Yourself?

Yes, for small areas of mold, less than 30 sq.ft. of contiguous mold, usually the job can be handled as an ordinary building cleaning or renovation project, with the provision that should the cleaner discover a larger mold reservoir during cleaning, the job stops, an expert is consulted, and proper safetuards are taken.

If you're not able or interested in hiring a mold professional, and/or especially if the total known moldy area is small

  1. Remove small mold areas yourself: For small areas of mold, it's appropriate to just remove it - if you are sensitive, fragile, or sick, have someone else do the work.
  2. Collect and hold on to some samples. If you're going to proceed anyway, try collecting some tape samples of what you see. Instead of sending these samples off to a lab, just keep the samples, but prepare them by following the sample collection instructions
    at Six Easy Steps to Get and Mail a Mold Test Kit - you can always save them to give to an investigator later if it becomes necessary to investigate further
  3. If you stumble onto a large area of mold during your cleanup (more than 30 sq ft) you should stop and consult an expert

More mold cleanup guidance is at

Reader Question: mold in rental property vents - what tests would be appropriate? Can I use a mold spray to cure a mold problem?

Daniel, I hired a 'professional' vent cleaning service to clean a rental home's ducts yesterday, against my better judgment, but to appease a difficult tenant.

As expected, they tried to 'upsell' the job, INCLUDING 'testing for mold', stating there were a few spots in vents that looked like mold. Upper level of home tested negative, Lower level tested positive. I've been told by a licensed HVAC contractor that it's common for a little mold to be present in many areas of a home, but highly unlikely for this to be problematic, given that we live in Albuquerque NM: high desert. The home is cooled by an evaporative cooler (vs refrigerated air).

Can you recommend how to best test this alleged mold? Also, when I was able to get the Vent Cleaner alone & 'thank' him for alarming the tenant w/ his mold comments, he stated that some simple, over the counter sprays from Lowe's or Home Depot could probably fix the problem (vs me paying him another $160 to do so) - L.W.

Reply: If there is no mold problem testing is not appropriate; if there is a mold problem, sprays alone are not a recommended "mold cure"

A competent onsite inspection by an expert, a real one, not an HVAC company trying to sell more duct cleaning services, can often finds additional clues that help accurately diagnose a problem, or that indicate that there is no evidence of a larger mold reservoir that justifies costly cleaning.

That said, it's true that often we find small patches of mold in HVAC systems and that an expert can find at least some mold in just about any building. Often a small Cladosporium colony is seen on HVAC ductwork just downstream from the blower fan in the ductwork. While Cladosporium sp. (the largest group of molds) contains some members that can be harmful to people, small immobile colonies of even a square foot or two are unlikely to be detectable in the building air.

Watch out: if the conditions that produced mold growth that you see anywhere in the building have also produced a larger but less obvious mold colony, say more than 30 sq.ft., and say of highly-mobile problem molds such as Aspergillus sp., the little, probably harmless mold you saw may not be the issue but it might be a pointer to a less obvious problem.

The article above is intended to help decide if an expert inspection and tests for mold are really justified and appropriate at a property. If the rules of thumb we describe above all fail to indicate that further inspection and testing are needed then it's unlikely that it is appropriate nor cost justified to perform more mold testing at your building as well.

The comment by your HVAC guy recommending a mold cure by applying sprays suggests to me that the person is not properly informed about mold.

Mold Sprays Alone are not a "Cure-all" for Indoor Mold Troubles

Sprays alone are not a "mold cure" and in some cases can even be a health problem themselves. There is a place for sealants and disinfectants but not as a "mold cure"

Find and Fix the Cause of Indoor Mold Growth

And furthermore, if there really were a mold problem, in the ductwork or elsewhere in the building, finding and fixing the cause of the mold growth is an essential part of a mold remediation plan. Otherwise the time, trouble, and money spent on the "mold cleanup" is simply wasted when the mold-growing conditions remain and a problem returns at the same spot or others in the building.

Amateur "mold inspections" can be Risky - do nothing or do it right?

If legal or health complaints justify a check of the building for mold, I would be certain it's performed by an expert. You don't want to be in the position of asserting that there is "no problem" if in fact there is one, since someone could get sick and you could bear liability for it.

On the other hand, as we discuss in MOLD / ENVIRONMENTAL EXPERT, HIRE ?, in the absence of good reason, a thorough inspection and testing for mold are not justified, and superficial tests (air tests, cultures, etc.) used alone, without an accompanying careful inspection would be unreliable.

Continue reading at MOLD / ENVIRONMENTAL EXPERT, HIRE ? or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


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