Simplified Mould Testing Overview - Pros and Cons of Different Methods

First I want to talk about the most reliable test which is how you feel in the house compared to other places. Unfortunately this is not always as simple as it sounds to execute. There are different ways to undertake this experiment. The simplest way is to stay in your backyard in a tent or all metal trailer without bringing any possessions from the house. The most obvious complication here is that you will need to go inside to use the washroom unless you get a porta potty! You may also be so sensitive that the house has contaminated the air outside (I have experienced being outside of a house and being able to smell the mould).

The next option would be to stay somewhere where other people recovering from mould illness (and MCS) have felt better. This could be a campground, KOA cabin, Airbnb or other rental. I have a lot more details on this in my post on the Locations Effect and Mould Sabbatical.

Once you have gotten "clear" and done some recovering you might be wondering how do you test a house to find out if it's good? Some people can walk into a house and know if it's good for them. But even the most sensitive people usually need to request to spend 3 nights trialling the house. This is not always an option, but you should ask. Usually people sleep better in a house that is mould free, but me and other CIRS patients have found that there is some mould that puts you into a zombie sleep where you sleep more (and then get sicker). So even a three-night test can be tricky.

It is also good to verify the house is safe with mould testing. The most common test for CIRS (mould patients) is the ERMI. It is highly recommended by Shoemaker certified doctors as the test to use. The range of the ERMI scores goes from minus 10 to positive 20. You need a score or 2 or lower to be treated and recover from mould illness according to Dr. Shoemaker.

Other types of mould tests can also be useful. A tape lift will get you definitive results on visible mould. I look at the options below. This is a very simple overview just to give you the general idea of what is out there in a way that is not overwhelming - you may want to look more into each of these different methods. Please note that my sources were biased towards mould advocates Lisa Petrison from Paradigm Change, Greg Muske from Biotoxin Journey, Dr. Shoemaker and Cheryl Ciecko, an architect who specialises in mould. I have attempted to cross-check their information. However, going with information from the companies that do house inspections can be biased and contradictory. (All sources at end of post, which you can read for more detail).

This post contains affiliate links to relevant products that I use and recommend. Upon purchase, I earn a small commission at no extra cost to you. I was given the Tape Lift test to see if I liked and recommended it.



- Doesn’t work well in brand new houses.

- You need dust that has settled for a while (wait 4-6 weeks to re-test an area).

- Having very little dust or a high amount of dust can skew results.

- Having a high amount of outside dirt inside can skew results. Having high or low outdoor spores counts can skew results.

- May not be an even distribution of spores throughout the house if mould is only coming from one place and the house is large.

- It is known to miss major mould problems when people are very sick in their house. Similarly, after a remediation, a CIRS patient can still be sick from the mycotoxins left behind despite a low score.


-"Only the ERMI and HERTSMI have been associated with sequential activation of innate immune responses, not air testing.” Dr. Shoemaker. Meaning it is the only test that he found that is consistently in line with lab results for CIRS, despite its drawbacks.

- Vacuum method can pick of heavy spores like Stachy and the Swifer method can also be used to pick up places with accumulated dust that has been there for 4 months. John Banta always tries to use the vacuum method over swipe method.

- It's pretty affordable at $300. You do it yourself. The lab recommended is Mycometrics.


-Similar to ERMI but tests for a handful of moulds most commonly associated with water damaged buildings. It is cheaper than ERMI. I would go for the full ERMI and you can still calculate your HERTSMI value from that. Shoemaker certified doctors will consider your HERTSMI score as well as ERMI score.

Tape Lifts


- You need to have visible mould.

- It assists you with what type of mould it is and not how widespread the problem is.


- Tells you what kind of mould you have when you have a visible sample.

- Allows you to know if this is a toxic mould.

- You can do it yourself.

- It's the cheaper way to test for visible mould.

I used this DIY Tape Lift to test a few areas in a house I go into often. The results came back showing me what type of mould it was. It confirmed that the mould was one that is toxic that comes from water damage. Though you need to get a decent amount of mould on the tape otherwise your results will just show scattered pieces.

Spore Traps (Air Test)


- Needs to be taken near the source, so you have to know where the source is.

- Shoemaker says: "The industry standard of sampling the air for spores is not an acceptable substitute for many reasons. One of the main limitations is that over 99% of the particles that carry the inflammagens from water damaged buildings are smaller than 3 microns. Spore traps can only detect particles that are larger than 3 microns and therefore, miss over 99% of the inflammagens.”

- Spore traps identify round, intact spores. So they will not catch evidence of past problem that have left mycotoxins.

- Can miss/underreport certain heavy species like stachy.

- Expensive.


- The test is more standardised than tape lifts, swabs, cultures, and mould-dogs, they claim.

- It is the most widely used mould test.

- You can compare inside and outside air.



- Hard to know where to place the dish to get capture the mould if you don’t know where the mould is coming from.

- Doesn’t get you an accurate relative reading since some mould is harder to catch and some proliferate faster in the dish than others.

- Stachy is a slow grower compared to other moulds in the dish.


- Can be used in multiple places to compare and for general observation.

- Can give you more details on the exact type of mould than other tests.

- Inexpensive.

- John Banta does a culture of the dust used for ERMI to compare and get more details

Here is one you can do yourself.

Mould Dogs


- Can only detect a handful of moulds.

- Hard to know if they are well trained, look for good references of the company.

- They can’t tell you if it’s high amount of mould or a trace from after a remediation.

- The dog can only sniff in areas where they can reach.


- They are good at finding the source if it is within their reach.

- The dog can smell both live and dead mould.

- You can pinpoint the area where you need to do further testing.

VOC testing


- There is controversy around the accuracy of this testing.

- Not widely used.


- Test the levels of mycotoxins and other VOCs in the air.

Here is a company that does this kind of testing that is recommended. It goes to an AIHA accredited lab.

Public postings by Cheryl Ciecko (Architect)
John Banta interview
Dr Shoemaker Q&A


Corinne Segura is a Building Biologist with 5 years of experience helping others create healthy homes.

For individual help undertaking mould avoidance you can schedule a consultation with me here.

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