Checking for Mold

Checking for mold at your home is not rocket science. I’m going to lead you through how to do it, step by step. In addition, I put up a second website,, which is more for decisions: Who should do the inspection? If you hire a conventional inspector, how can you pick up the slack? Should the remediation be done by professionals, or could you attempt it? What kind of remediation is effective? For decisions, check out that site.

When you hear the words “mold in your home,” what comes to mind? Respiratory, allergies … expense? I will explain this subject in terms you can understand. We’re going to travel together far beyond mold on a shower curtain or window sill. So let’s get started!

Isn’t mold everywhere? Yes, spores are everywhere. You open a door. Spores float in. You come inside the house. Spores could be on your shoes, your coat. These examples are not what we’re talking about with mold concerns.

What’s important about mold in your home is that you don’t want to have mold GROWTH. It’s the growth that makes a multitude of spores and other tiny particulates. It’s the growth that makes the musty, moldy smell. Checking for mold focuses on finding and eliminating sources of mold growth.

Too many mold particulates and too much smell can harm your health. These have been linked with everything from inflammation to infection, from sinus and asthma issues to headaches and depression, from sleep disturbances to pulmonary hemorrhages (in infants), and from dizziness to inability to focus.

Some of the latest research centers on the inflammatory aspects of mold particulates that are much smaller than mold spores, i.e., “microparticles.” If you’d like an email copy of this research, please email me at


You can’t adequately clean up mold unless you know where it’s growing, so the first step is to locate the sources of growth. Then, you have to know how to clean up the mold. Lastly, take steps to keep it from coming back.


Many times, cleaning up mold is a homeowner’s maintenance job. Often, cleaning up mold can be done by a non-professional. Sometimes it’s better to bring in the mold professionals – but always, always, you should know what you want and what the pitfalls are with working with mold professionals before you hire anyone.

What on earth is THAT supposed to mean? Aren’t the professionals trained to do the right thing? I mean, they come with hazard suits and set up containment and negative pressure and they charge big bucks, so they must know what they are doing.


Let me tell you a story, similar to what I hear continually when I’m checking for mold. A mold inspector took air samples in a home and reported that there were elevated levels of mold in the master bathroom and in the basement. By the time the homeowners were finished gutting the master bathroom and doing clean-up in the basement and changing this and that with the sump pump and the HVAC (heating, ventilation, and air conditioning) system, they had spent $25,000.

The homeowner called me the other day and expressed her doubt about the remediation job that had been done. I, trying to get a sense of the situation, asked her where the mold had been found originally, i.e., where were the sources of growth? She replied that no one knew. All that work was done based on air sample results.

Oh my. You gut a bathroom because of elevated mold counts? First of all, if there is a serious problem behind walls or under floors, it’s typically not going to show up in air counts. If air counts are high, the cause has to be something that is in contact with the air. Maybe there was just mold in the bathroom sink cabinet from a past leak. Maybe just the base of the cabinet had to be cut out and the area cleaned and treated with a sealant.

Maybe the basement just had the average amount of mold on ceiling joists and subflooring, similar to just about every other basement in town. Maybe just some cleaning and sealing was needed. Maybe the family’s vacuum cleaner needed to be upgraded to a true-HEPA vacuum cleaner.

If a proper diagnosis had been done, maybe what needed to be done could have been done for $2,000, instead of $25,000. The lesson here is that if you don’t watch out for yourself, you could be taken by a $25,000 job instead of a $2,000 job.

Who is at fault here? By and large, mold inspectors do the job they were trained for. Remediators depend on the mold inspectors to tell them where the mold is. When the final post-remediation test results come out good, everyone thinks they have done a good job. They pick up their checks and head off to the bank with a smile on their face, that another good job is behind them. They are happy that you are happy and that your mold is gone — but is it?

All too often, the homeowner is left paying far too much, maybe left with mold growth since not all the sources were found, and is unsuspecting about the reason for the continuation of symptoms.


If you think it through and re-read the above couple of paragraphs, you see where the fault lies. The mold inspectors are not adequately trained for what they have to do – by anyone, even the best of the professional training organizations. Of course, this is just my opinion after close to 25 years in the business.

What’s wrong with the training of the mold inspectors? The answer is simple. After checking for mold, the inspectors send all samples to a microbiology laboratory, and they can’t take enough samples to have all the data they need. The lab fees would break the bank. Plus, inspectors depend on finding mold that’s visible for their sampling. BUT MOST MOLD IS INVISIBLE – even high levels of mold. The visible mold may not be the most important mold in a home. So the inspectors need to find something that’s often invisible – and they don’t have the tool to do that.

The dilemma could so easily be resolved. Any high school biology student could tell the mold inspectors what can be used to look at tiny, invisible structures: a MICROSCOPE.

High school biology students successfully use microscopes… but a mature, trained, experienced mold inspector can’t bring a microscope to an inspection? Why on earth not? What’s going on here?


1. The mold industry is built on lawsuits, and everyone is out to protect his or her back. The inspector is not a certified microbiology laboratory. The fallacy here is that it doesn’t have to be an either/or. The inspector could do the grunt work with the microscope and send some selected samples to the lab for independent third party confirmation.

2. The inspectors, because they haven’t worked on-site with microscopes, don’t know what they don’t know. This is hazardous in any profession. They, along with the homeowners, float along on false assurances. The inspectors pass their limitations on to the remediators, who follow instructions from the inspectors. Because powerful air scrubbing machines were recently turned off, the post-remediation air sample test results are good.

3. There is no one to train them with microscopes. The few schools that exist go into far too much detail that is not relevant to home inspections, leaving the home inspector not knowing which way is up when it comes to working with a microscope at a home. If YOU are interested in learning to use a microscope, send me an email, and I’ll forward you some basic instructions – free. If you are a mold inspector, I WANT you to be able to do the best for your clients, because I know that’s what you want, too. If you are a homeowner, you can get yourself a microscope for a few hundred dollars and do your own inspection. If you represent a training school for mold inspectors… get with it. Please, people’s health is at stake here. Parents want the best for their children. They aren’t interested in papering their walls with good lab results, only to still have mold growth in their homes.

4. Inspectors make money with an override on lab fees. Ohhhh, you didn’t realize that, did you? Some is justified, for processing and handling, but some overrides are even three or four times the lab fees that the inspectors pay. Some labs offer special arrangements for inspectors who use them.


At this time, unless you can find an inspector who works with a microscope, you need to find a way to do your own inspection before your inspector arrives – if you even need to hire an inspector at all. You would do well to know what the score is before you get involved with the mold industry.

How do you manage that? There are a few ways that I know of:

1. Find an inspector who works with an on-site microscope. I do and inspect mostly in PA, NJ, NY, CT, MD, VA, and DC, plus down the East Coast to South Carolina and Georgia (several times a year). If you find anyone else who works with a microscope, please let me know. If you want to talk with me about an inspection, send an email to

2. Do tape samples on your own and either send them to me or find a microbiological laboratory that will assess them for you. Since I am not a certified lab, I charge a fraction of what a lab would charge – like 3 samples for $25, 20 for $100. You even get pictures of your mold, since I attach a webcam to my microscope. See the Testing tab for more information on how to sample and where to sample.

If you need samples for a legal purpose, you should hire a certified mold inspector and work with a certified laboratory, because my work is “in-house,” for your information, not for legal documentation.

3. Work with your own microscope. Instructions are posted elsewhere on this site. If you have trouble, bring in a high school biology student to show you how to work the microscope.


If you know where the sources of mold growth are in your home, you get to call the shots. You know what you want. You know what needs to be done. Now you just have to find the company that will work with you. You essentially are working as your own mold inspector and developing the guidelines for the remediator.


A lot of mold is hidden – hidden in wall cavities, hidden above drop ceilings, hidden beneath the base of sink cabinets. Once some demolition is done, you will have access to areas that you couldn’t reach before. Could those areas have hidden mold? Is more demolition needed? Checking for mold may not be so straightforward.

You have two choices: either do more demolition than you believe would be necessary and treat those new areas, too – or figure a way to work with a microscope and do some more sampling to make sure the end of the mold has been found.


I was called in to do an investigation in one room of an apartment, a room where there was a smell of mold. The room was empty, except for a window AC unit.

I set up my microscope and started testing. I touched tape to surfaces of the AC unit and found Cladosporium mold on the coils. Next, I wrapped tape around the end of a microscope slide (you could also do that with a kitchen knife or even with a credit card) and slid the slide under base molding. I checked base molding in several spots all around the room, with the thought that if there was mold in the wall cavities, it typically would show up at the bottom of the base molding.

I found elevated levels of Aspergillus/Penicillium-type spores under base molding, providing evidence that there had probably been a flood in the room or at least in the wall cavities (from an apartment above) at one time. I drilled a few holes to test for air testing. (My inspection went beyond that one room, but nothing was found beyond that room.)

My report called for remediation of the affected walls, including removal of the base molding and the walls, etc. Air sample results were bad for the wall cavities but fine for the room.

Meanwhile, the landlord had brought in his own hygienist inspector. This individual did the conventional inspection. He took some spore trap samples of room air. He looked around and saw no sign of mold growth. The only red flag he saw in the room was the AC unit, which had mold on the coils, so he figured that was the likely source of the mold smell. His report called for having the AC unit cleaned.

The woman who lived in the apartment witnessed first my inspection (which went beyond industry guidelines) and then his, which was in accordance with industry guidelines. She later told me that she said to him at the end of his inspection, “Pardon me, but I don’t think you are doing your job.”

But he was – according to industry guidelines – but he wasn’t – if her health was the prime consideration. I rest my case. He missed the main sources of the mold.


A microscope is my main line of investigation when checking for mold, but I almost always do air sampling, too. Tape-sampling, as valuable as it is, is a spot-check. Air sampling is a back-up type of testing. Sometimes air sampling gives me a surprise…which may lead to additional investigation or recommendations.

I prefer to do culture plate sampling (where live and culturable mold spores grow on nutrient material in a Petri dish) because it is superior to spore trap testing (where both dead and alive spores are counted) for diagnostic purposes.

I almost never depend on air samples alone, except maybe in post-remediation testing where all accessible surfaces have been encapsulated.

Now, however, we have another tool in the toolbox: DNA testing (formally known as MSQPCR, or Mold-Specific Quantitative Polymerase Reaction). That’s a mouthful for counting mold particles in a dust sample. Thanks to Dr. Joe Spurgeon, we have a way to compare numbers of mold particles for hard and soft surfaces and for an HVAC supply or return vent. Go to the tab for MSQPCR. With this comparison, you can determine if your HVAC system is contaminated and get a sense of the moldiness of your home or office. Go to the tab for DNA Testing.


Check out the “Scenarios” tab for an overview of what to expect with remediation. You may hire a mold remediator or you may decide to do the work yourself, depending on the scope of the work. Either way, you need to familiarize yourself with the process and with the precautions.

To see an example of how cleanup works in more detail, go to the “Sample Report” tab.


Once your mold is gone or treated (cleaned and/or sealed), what can you expect?

  • There will be no more production of mold spores and other particulates from mold growth.
  • Once mold growth is gone, mold gases will no longer be produced (though clothing, carpeting, and furniture may have absorbed musty odors).
  • You can go on with your life, continuing with good housekeeping practices, including use of a HEPA vacuum cleaner, damp-dusting, keeping the house shipshape with few dust-collectors, and practicing in-depth spring and fall cleaning like your grandparents did.

QUESTION: I have remediated in my basement, but it still smells musty.

RESPONSE: Older basements can smell musty. Either dehumidify it or, better from an energy standpoint, look into the Wave, I’m considering that for my own basement after several clients gave endorsements.

If you consider the Wave, make sure you are clear where make-up air is coming from, or undesirable air may be drawn into the basement, such as from an attached garage. If there is insufficient make-up air, carbon monoxide could be produced.

Where is your carbon monoxide detector? Did you know that carbon monoxide rises? The detector should be on the ceiling.


Next up, Instructions for Tape Testing for Mold.