|Teach Yourself Environmental Home Inspecting|
Finding the sources of mold growth is important, because without knowing where mold is growing, how do you know how to clean it up and to keep it from coming back? Neither air nor ERMI/Hertsmi testing tells you where the mold growth is.
Mold growth is linked with health concerns and results in some or all of the below:
increased numbers of spores (which could be allergenic or, in some cases, even grow in human tissue, particularly
microparticles (which are broken up tiny pieces of spores and hyphae, the branchlike structure of mold growth, and could be inflammagens, i.e., provoking an inflammatory cascade in the body)
mycotoxins (which typically are not volatile, but could be released during inadequate cleanup); Stachybotrys is likely the worst offender here, though Trichoderma can make the same mycotoxins.
MVOCs, or volatile organic compounds produced by mold. In my experience, MVOCs are underrated. Many people are sensitive to mold gases which may be neurotoxic or contribute to other symptoms. Air testing for MVOCs is inadequate; the better approach is to locate the sources of growth and eliminate them.
What does mold need for growth? Food and water.
The food would be typically organic matter, such as the paper backing of drywall, wood, paper, cloth.
The water could come from a plumbing leak or overflow, from water intrusion from the outside, from the air-conditioning system, or from prolonged high relative humidity, among other sources.
Why do we work with a microscope to investigate mold growth?
Because most growth is not visible to the naked eye, and most mold is hidden.
Hidden mold would not show up in air samples or in ERMI/HERTSMI-2 samples.
The health concern relating to hidden mold has to do with the mold gases. These gases emanate from areas of growth into room
Aspergillus and Penicillium can continue to grow in hidden areas from just the relative humidity of unconditioned spaces. They do not need continued wetness. Stachybotrys, Trichoderma, and Chaetomium have higher needs for water than Aspergillus and Penicillium do.
What do I need to tape sample?
Pen, paper, one Ziploc bag, permanent marker (optional)
Three-quarter inch, clear or transparent tape. Scotch brand Multi-task tape is also fine. Do not use Magic tape, satin tape, or packing tape. Samples may have to be re-done, especially with Magic tape. The light from the microscope will not penetrate through Magic tape, and all I will see is a cloud.
Something stiff and thin, such as a credit card, butter knife, or putty knife, to slide under base molding and into cracks.
Take approximately a 3-inch piece of tape.
Stick one end on your thumb and the other end on your index finger, sticky side out.
Press down in the middle of the tape onto the surface you wish to sample. I press down with my index finger, positioned near the center of the tape, for more control in sampling.
Feel free to press the middle of the tape down on more spots on a similar surface. We want to know if there is any mold, and if it is a lot or a little.
When finished sampling, make a quarter inch tab on one end of the tape.
Place the tape flat out on the OUTSIDE of a Ziploc bag, as if you were placing a Band-Aid on the bag. All you need is a mounting surface.
Using the permanent marker, put a number on the tape by the tab.
If you cannot be exposed to permanent marker chemicals, then write the number on a little piece of paper and stick it at the end of the tape.
Ballpoint pen numbers on plastic can be hard to read.
Placing the number on the tape, rather than next to it, is a quality control measure. If the number is on the tape, the tapes can’t get mixed up.
Make a list of the locations for each number.
Enclose a check made out to EnviroHealth as follows:
$15 – 1 tape
$25 – 3 tapes
$50 – 8 tapes
$100 – 20 tapes
Over 20 tapes: $100 plus $4 per additional sample. If you later send more tapes, they, too, would be $4/sample.
Mail first class to:
1009 Hemlock Circle
Manheim, PA 17545
Include your name, phone number, and email address.
If you need a rush, please call ahead to make sure accommodation can be made.
Do not require a signature.
Is tape sampling enough to discover a mold situation?
Tape sampling is my best tool but not my only tool. Air samples can sometimes pick up on mold conditions that tape testing misses, or underestimates. If you have health concerns, you are encouraged to also have air sampling done. If you live in my catchment area (extending out from Pennsylvania), give a buzz. Or, call a local inspector and have AGGRESSIVE samples done, i.e., stirring up dust. Also, for central air LINK***, consider sending a swab to Assured Bio Labs for DNA-level testing. If you forward a copy of the DNA results to me, I will help you interpret the findings.
Tape are one testing modality, but not the only one. I am working on a report from a recent inspection. The tape results weren’t bad, but the air samples told another story. I sample in every room, because then we can see patterns of growth/dissemination.
Since I can work with a microscope, there are no lab fees. The report would be just for the client’s information, not useful for a legal action, since a certified lab is not being used. Some samples of course could be sent off to a lab, if the inspection were for pre-purchase or some other purpose where a paper trail is needed.
Here, I will walk you through where I sampled on a recent home inspection. Hopefully this will be helpful to you in thinking through where to sample at your home.
Two discolored spots were sampled, one dark and one light. Both were negative for mold.
If mold is growing in an attic, often it is visible:
There may be dark stains on roof decking of the north wall or on lower decking by soffits. Cladosporium (occasionally Ulocladium) grows in areas of condensation.
Try treating with Fiberlock’s Advanced Peroxide Cleaner, available on Amazon. Cladosporium and Ulocladium are black molds, containing melanin to protect them from UV C exposure. The mold may be removed, but the stain remains, so stain removal is also recommended.
If you see white fuzz where rafters meet roof decking, that is Aspergillus, and the cause is too much moisture in the attic, with insufficient ventilation. Check that bathroom exhaust vents do not terminate in the attic. Take steps to improve ventilation.
The modern approach to attics, especially when ductwork is in the attic, is to put Styrofoam boards between rafters, or to apply foam insulation (which can make a royal mess if not done properly - I’d be cautious). The attic becomes part of the living space.
At Addison Homes in SC, ductwork is always in conditioned spaces, whether in the attic, basement, or crawlspace. This avoids condensation and other issues.
Roof and flashing leaks are common. Follow the path of the water to find the mold. If there is a chimney, use a strong flashlight to look down at the sides of the chimney. If rainwater gets in there, Stachybotrys can grow.
Odd spots and discolorations. These are not always mold, one trick is to touch the tape to the discoloration and hold the tape up to the light. If nothing or only crumbly stuff shows on the tape, the discoloration is probably not mold. If the tape has a film, it may be mold.
Another trick is to hold the flashlight parallel, resting on the wood. The light will make fuzz easier to see.
Mold can grow on windowsills due to condensation. This is typically Cladosporium again. Insulation may be inadequate around the window, or perhaps there is single pane window glass.
Mold can grow from leaks, such as inadequate caulking on the outside of the window. Follow the path of the water to find the mold.
At the client’s house, we knew there had been a leak from a window air conditioning unit into the wall cavity. There were several options for confirming mold growth, though we were pretty sure there would be hidden mold in the wall cavity. Sometimes the logical question to ask is, “Well, why wouldn’t mold be growing there? There is food and water.”
There are several ways of testing for hidden mold in wall cavities:
Use a moisture meter for a clue as to whether the drywall has elevated moisture. A simple pinless moisture meter can be found online for about $30.
Drill a hole and take an air sample in the wall cavity. You likely don’t have the equipment to do this.
Cut a hole and take tape samples. Opening up a hole in the wall may release mold particulates to room air and may not be advised. At the least, hold up the nozzle of a HEPA vacuum cleaner to the hole to capture dust and mold particulates. Use a box cutter to minimize release of drywall dust.
Wrap tape around the end of a putty knife, credit card, or blunt kitchen knife and stick the putty knife under base molding in a few spots. If there is mold in the wall cavity, very often some will grow under base molding.
Sometimes there is a quarter round decorative strip at the bottom of the base molding. This strip may be too tight against the floor to get under base molding.
Sometimes carpet is very tight against base molding, and you cannot get a good angle with your putty knife for sampling. Do the best you can. I have often found evidence of mold even with this sort of limited testing.
Modern, minimalist, and laminated furniture generally wouldn’t have mold growth. But if you have antique, hand-me-downs, furniture from garage sales, etc., sampling them is advised.
Do composite samples, as a quick way of screening. That is, touch one tape to all the furniture in the room. Touch the tape on the undersides and, if accessible, lower backs, as well as upholstered surfaces. You might be sampling 20-30 spots with the same tape. If the microscope reveals mold on the tape, then send me break-out tapes to find the guilty party.
If the bed frame has wood slats, sample them. If you have a Sleep Number bed made before 1994, lift the top layer and sample at the membrane.
Was there a leak or spill? If there was a leak, would mold be on the surface of the base or might water have penetrated beneath the base? Touch various areas around the plumbing, as well as where the rear wall meets the base.
Tape sample on the edges of access holes where pipes go into the base or back of the cabinet.
If pipes go into the back of the cabinet, air testing via a tube may be needed but is not likely to be something you could do. At least you can test the edges of the access holes at the pipes.
Note: If you have PEX plumbing pipes, there is much less likelihood of leaks. These are plastic pipes that run straight from the source in the basement to the termination point, without any joints or connections in between. For example, one run would be from the basement to the hot water at the sink. Another pipe would run from the basement to the cold water at the sink.
If the sink is on the first floor, and if there is a basement or crawl space where subflooring is visible, look for signs of water intrusion underneath. Also look under tub fixtures and toilets. Sample as needed. Many times, whitish material on wood around the pipes doesn't have much mold.
Was there a toilet overflow? Do the putty knife sample under base molding behind and adjacent to the toilet.
Older toilet tanks may not have the insulation of newer tanks. Condensation forms on the back of the older tank, and Cladosporium can grow. This is a maintenance issue to clean off the Cladosporium. Update the tank when you can.
At the shower, gauge the grout. Are there any gaps in it, where water could penetrate? Stachybotrys can grow in areas such as this, where there is continual wetting. Many contractors think that green or blue board is mold resistant, but it really is not. Hopefully, cement backer board was put behind the shower.
Sometimes there is a shower access panel. If so, take it off, and look inside with a good flashlight. Look for signs of black mold on lower drywall. If there is no shower access, go to the other side of the common wall with the shower and try the putty knife under base molding, assuming you have access.
If there is water staining on the ceiling, determine the source. If water found a way out, such as through a light fixture, there would be reduced chance of mold growth. However, the risk for mold may be 50-50.
There is nothing that you can test here unless there is black or green discoloration on the paint. Paint typically has a mildewcide and would be negative for mold growth. However, there could be hidden growth in the ceiling cavity from either a plumbing or roof leak or an ice dam.
If you are able to access this area from an attic, perhaps any mold could be wiped off and the area painted. Wear a mask around both mold and fiberglass or cellulose insulation.
If the water stained area is accessed from the room, you may be looking at a mold remediation job; if it can be accessed from the attic, it may be a clean-up job.
If any part of a room is below grade, moisture may have seeped through the foundation into the wall cavity, and contributed to mold growth in the wall cavity. Try the putty knife trick under base molding. A moisture meter should also be used here.
If there is a patio on the other side of the room, tape-test under base molding along the wall. Too often, patios slope toward the house instead of away from it.
If a downspout ends at the foundation and there is potential for moisture seeping through into the wall cavity, tape-test under base molding along the wall.
Gauge the risk for rain water seeping into the door frame and under the sill. Use the putty knife to sample underyg and in cracks and crevices.
Concrete is not waterproof, and when walls are put up, there is risk for moisture intrusion in the wall cavity, thus raising the humidity and fostering mold growth. When folk are shopping for a healthy home, I recommend, "no finished below-grade spaces." This caution would also go for a bi-level home where the lower level is partially below-grade.
Basements were originally meant as buffer zones between the house and the ground, used as root and wine cellars and for storing canned goods. An unfinished basement is accessible for testing.
Not every finished basement has issues. There may be thick insulation in the wall cavities; the ground may be dry with good drainage; maybe the contractor knew how to finish the basement and keep the risk of mold growth low by using mold-resistant materials, such as magnesium oxide wallboard and composite base molding, etc.
Tape-sample with a putty knife at spots under base molding, like one tape for every wall, sampling 3-4 areas under base molding along the wall.
Sample the furniture. If relative humidity (RH) is too high for too long, mold can grow. The recommended RH for a below-grade space is around 50% or lower.
Carpeting is generally not recommended on slabs. Mold can grow in carpeting on organic matter; mold particulates accumulate in carpeting and are not completely removed through vacuuming. Carpeting is not a good investment for health, either on a slab or elsewhere.
A question to explore is: Does mold grow on the structure of this basement? Two tapes may be all that are needed to answer this question.
Tape sample under the bottom step of wood stairs to the basement. Aspergillus likes to hang out in this area. If there is significant Aspergillus growth, the basement likely can support a fair amount of mold. Little or no growth is a good sign.
Tape sample at several locations of ceiling joists and subflooring around the basement. Ceiling joists are the beams on the ceiling. Subflooring is the plywood or wood supporting the first floor.
Look for signs of visible mold. Remember the trick with holding the flashlight parallel to a surface? This can make fuzz easier to see.
Should there be elevated mold in these areas, there may be mold on ceiling joists and subflooring above the ceiling in the finished area of the basement.
As a general rule, if contractors or owners of new construction knew to paint every square inch of wood in the basement, there would be less mold in basements. Painting protects the wood against mold, perhaps not if the basement gets flooded, but under normal circumstances.
Surfaces to be painted include: wood backing of electric box, worktables, wood or pressed wood shelving, stairwells, ceiling joists, subflooring, and cross supports between ceiling joists.
Tape-test pressed wood shelving if present. Some pressed wood shelving has a high level of Aspergillus.
Tape-testing the top of cross supports provide a kind of history of mold in basement air, because no one cleans on top of these… including many remediators.
Unprotected wood may be lunch for mold. Ceiling joists and subflooring may need to be treated, depending on the level of mold on them.
If you set off something smelly, like sage incense, in the crawlspace, and see if the smell comes upstairs, you will know if crawlspace air is infiltrating into the living space.
At one house, the incense smell came out of every supply vent. The homeowners realized how leaky their crawlspace air-conditioning ductwork was.
As with the comment in the attic, the modern teaching is to seal the crawlspace off from the earth, close off vents, put insulation on the walls, and make the crawlspace part of the living space.
Tape-testing is limited for central air. If you can reach the AC coils, sample them. Sometimes you will see black mold growing on a supply vent cover. This typically is Cladosporium, localized at the diffuser because of condensation. Growth here is not a statement about the rest of the system.
The better way to get a clue as to what might be happening mold-wise with the central air system is to do a swab on the slits of a supply vent cover and forward that to a lab for DNA testing.
Call Assured Bio Labs (800-824-1700) and ask them to send you one sterile swab for each AC unit/zone. Either ask them to email you a Chain of Custody form (which you will fill out and return with your sample) or download one from their website.
This form will have a place for your name, address, email, and phone number. You need to write down what test you are ordering, so that the lab knows what you want them to do. Here are the two choices:
CAP 15, which identifies 15 of the top species listed on the ERMI test. Cost: $145/per swab.
Big Two, plus added in Chaetomium and maybe Cladosporium. These results lump Aspergillus and Penicillium species together and also give you Stachybotrys and, add-ons, Chaetomium and Cladosporium. Cost: about $75 plus $15 each for added Chaetomium and Cladosporium.
When you receive the swab, rub it back and forth, back and forth, back and forth on to gather dust from the slits of an AC supply vent cover (where the cool air comes out into the room). Press down so the swab makes contact with the slits.
I’d rather get too much dust than not enough. We’re just looking for a clue about the species of mold and whether the levels are typical or point to contamination.
Place the swab in the cylinder (twist off the top), and mail back to Assured Bio Labs, first class mail, package rate, a little more than $3.
When you get your lab results, there will be some elevations, because AC systems are not sterile environments. I have charts to help interpret whether the findings are typical or point toward contamination. Feel free to email me a copy, and I will help you interpret the findings. If you would like a written report, that will be $25. Verbal discussion, no charge.
Based on findings, recommendations will be made. Sometimes actions are needed that conventional duct cleaners would not be aware of. See AC Testing.