Guide to Mold Testing in Your Home
“How do we test for mold?” is probably the most common question we hear from families that suspect mold in their home. What should you do first? What tests are the best? Should we just hire a professional?
Mold Testing Options
The options can be totally overwhelming! Below, we will highlight the 5 most common types of tests and give you the pros & cons of each.
First, some basic principles to understand/follow:
#1) There is no perfect test for mold! Each test has it’s pros & cons (described below). If anyone tells you otherwise, they aren’t being honest. Each test has it’s place in a larger strategy and different tests will make sense for different situations.
#2) The mold tests below can all be ordered directly and don’t require a professional. If at any point you feel overwhelmed or intimidated by the process, we recommend that you hire an IEP (Indoor Environmental Professional).
Pros & Cons of the Most Common Mold Tests
#2 ERMI/HERTSMI Mold Test - Dust Sample
This is the test that has become the most popular for DIY mold inspection and has become very popular in different mold Facebook groups.
Tip: There are other dust sample mold DNA tests that use the same technology but test for less species and may cost less.
COST: $225-$400
Pros:
Relatively inexpensive and uses reliable technology (qPCR - DNA Testing).
Easy to do - collect dust samples on a swiffer pad throughout your house.
It can tell you immediately if you have a problem somewhere in the house with a dangerous species of mold.
Gives a historical picture of mold problems in the house.
Cons:
If the test comes back with high spore counts, there is no way of knowing where the problem area is in the house.
The ERMI scoring system is based on a very small sample size of houses and is well known to be a poor representation of houses in the United States. Meaning that the scoring and interpretation are almost completely useless.
It’s Easy to not collect a large enough sample which will skew results.
You may want to consider an ERMI interpretation service or hiring a professional to help you interpret the results.
Bottomline: The ERMI is an inexpensive DIY option that uses advanced technology, but does have some limitations and is only one of many dust sample DNA testing options.
Where to Order:
#1 Mold Air Testing
This is what most IEPs (Indoor Environmental Professionals) will use to test your home. It makes sense intuitively because generally you are exposed to mold spores through the air you breath.
COST: $600 and up - Depends on the professional conducting the testing
Pros:
If done right, air testing can help identify a problem behind a wall where there is suspected mold from water damage.
Depending on the lab the tester chooses, the technology for identifying mold species is very advanced and uses qPCR which identifies the DNA of individual species.
It's a great tool in a professional's toolbox. If the tester is taking targeted samples based on a potential problem area, and backing those tests up with a mycotoxin or surface sample, you can get extremely accurate results and really pin point a potential issue.
Cons:
Frankly, many testers don't know what they are doing. If they sample from the middle of the room, ask you turn off HVAC, close internal doors, etc, they aren't getting an accurate representation of the air in the house on a normal day.
If a tester tries to use the outside air as a control and judges the results solely on the comparison with the control, the results can be very skewed and misleading.
It can be crazy expensive. The cost of the tester coming out, then the cost of the lab fees for each sample. Every time we've done air testing it has cost between $600-$1,000.
$240, 5 Day Turnaround Time
#4 Mycotoxin Testing (Dust Sample)
Also referred to as an EMMA test. Mycotoxins are the toxins that mold produces which is widely believed to be the chemical that causes most people health problems. Not all mold spores release toxins so it can be very helpful to know not only if your home has a mold problem, but if the mold that is present is producing harmful toxins. This molecular test identifies the actual toxins released by mold spores and identifies the most dangerous toxins. Mold spores are between 1-20 microns in size. Mycotoxins are only 0.1 microns in size, making testing for them highly specialized. Only a few labs in the world are able to test for and identify mycotoxins.
COST: $360-$399
Pros:
Very advanced technology for identifying problems at a toxin level.
Identifying specific mycotoxins in the environment can be compared with mycotoxin urine tests to match up environmental and health symptoms.
Most labs that run mycotoxin tests now also include DNA testing for mold spores so you get a 2 for 1. This may eliminate the need for a stand alone mold DNA test for many people.
Cons:
Similar to other dust sample tests (this test is typically a swab taken from HVAC) this is a "whole house" test and doesn't identify where in the house the problem area is.
It is the most expensive out of all the DIY tests.
Interpretation of these types of tests is important and you may need to hire an expert to help you understand the implications of the results.
Where to Order:
#3 Mold Plate Testing
If you go to Home Depot and buy something off the shelf to test for mold, it's most likely going to be a plate test. Technically they are gravity plates. These basically look like petri dishes that you leave out in certain areas and over time (in theory), airborne spores will fall on the plates. After some time, you put the lid on and culture it yourself (put it in a dark place for a few days and see if any mold colonies pop up), or send it directly to the lab for them to culture and identify for you.
Pro Tip: To use mold plates effectively, forget about doing a multi-day gravity test. It's a waste of time and isn't very accurate. Instead, do a "tap test". Turn the plate upside down, place it on a porous surface like carpet, furniture, curtains, etc, and tap the bottom of the plate a few times. This will disturb any mold spores that are collected in the porous surface and capture them on the medium inside the plate. You can then put the lid on immediately and culture the plate or send it off for testing.
COST: $3 per plate with no lab testing, $33 per plate with lab testing
Pros:
Inexpensive. Especially if you culture the plates yourself. This is the most affordable testing option out there.
Plates can give you a quick DIY way of seeing if you have a problem.
They are cheap enough that you can buy multiple plates and test multiple places which can help identify where you may have a problem if you are unsure.
Cons:
You will have to spend extra to send plates to the lab if you want to find out the types(genus) of molds that you captured in the plates.
Most labs that interpret the tests will not identify mold down to the species level, making it difficult to draw real connections to health problems.
Mold plates can be temperamental. Many that you buy off the shelf from a store can dry out quickly and lose effectiveness long before their expiration date. Make sure to use a reliable lab, and use the plates as quickly as possible for the best results.
Where to Order:
$360, 10 Day Turnaround Time
Note: currently the best deal for mycotoxin testing. Includes DNA testing for 10 mold species.
#5 Tape Testing For Mold
This test is the least sophisticated out of all the other tests but has the most “cool” factor. I mean, sticking a piece of tape to some dust in your house and then having a scientist look at it under a microscope and send you the pictures of actual mold spores, rooting structures, and mold fragments… that is pretty cool. But this testing method has it’s clear downsides as well.
COST: $15 for a single piece of tape, and the cost comes down the more you purchase.
Pros:
Because of the cost, you can potentially sample dozens of areas in your home.
A good technician will be able to identify the genus of the mold and send you pictures. For example, Chaetomium has a distinct football shape and is brown which makes it easy to identify.
If you are unsure if you have a mold problem, or have multiple smaller problem areas that you suspect, tape testing can be a great way to inexpensively isolate a potential problem area.
Cons:
The mold species can be very difficult to identify under a microscope. For example, Aspergillus, while easy to identify at a genus level, can be difficult to differentiate at a species level
Unless sampled from visible mold, the material on the tape may only include spores, parts of rooting structures, or other organic material from mold that is broken apart. This can make it difficult to identify the type of mold.
The instructions can be a little confusing and if you don’t follow them precisely, you may not pick up material on the tape that can be seen on the microscope.
Where to Order:
This is one of my favorite recommendations because I seriously love this lady (May Dooley). She is a former elementary school science teacher that taught herself how to identify mold under a microscope and also conducts inspections on the east coast. She is an amazingly generous and kind woman that is a wealth of information and truly wants to help you identify potential problem areas. Her tape tests are affordable and come with a helpful analysis and thoughtful suggestions. Can’t recommend her enough!
LINK: Instructions on How to Test & Send in Your Samples
#6 Canine Mold Testing
COST: $500 and up. Depends on the dog/handler team and potential travel costs.
Pros:
Mold dogs can be extremely accurate and sniff out problems behind walls, in floors, and even in ceilings.
The results are immediate and can be very useful if you have had previous tests (like an ERMI) that show a mold problem but you aren’t able to identify the source.
A good handler will be able to guide you through follow up steps, help determine the extent of a problem, and give context to why a dog might be marking a particular area.
Cons:
Obviously a mold dog can’t tell you what kinds of mold you are dealing with.
Some skeptics say that mold dogs will give false positives. We’ve never known this to be the case. In every situation where a mold dog marked a wall and we opened it up, we found mold.
There are many parts of the country that don’t have mold dogs yet and hiring one from out of state can be extremely expensive.
Believe it or not, there are dogs that are specially trained to sniff out mold. This is an emerging testing method and there is even a dedicated Mold Dog School now that is turning out many great dog/handler teams. We have personally used a mold dog on 6 different occasions at our old house, new house, and houses that we were considering purchasing so we are very familiar with the process. Dog training is also near and dear to our heart because our family has a professionally trained service dog through Victory Service Dogs and we understand the intense commitment it takes to train an animal to complete complex tasks.
Buddy testing our current house
Each time our local mold dog in Colorado (Buddy) did a run through of a house, we learned something valuable and were impressed with his level of sensitivity. On one occasion, in a storage room, out of hundreds of items, Buddy marked multiple individual items and we later discovered that each item was from Lori’s childhood home - that wasn’t a coincidence.
On another occasion, Buddy marked on an exterior wall that didn’t seem to have any kind of potential water source nearby. But upon further inspection, when we went outside to examine the exterior wall, there was a hole in the siding that we didn’t see before and it clearly must have let moisture in and created a mold problem in the wall.
MicroBalance Test Plates Only
Test Plates & Lab Testing
