What You Need to Know about the Mold Industry

This tab addresses what you need to know about the mold industry. As a philosophy professor told our class, If you don’t have your own opinion, someone else will give you his.

Before you get started with this tab, make a decision about whether you want microparticles addressed (fogged and wiped down) or not. This is beyond what conventional mold remediation does.

The tab above this one, Cutting Edge Information, contains microparticle information that may be relevant for your mold remediation job. If you want microparticles removed (and not released) during a remediation project, you need to get a sprayer and the product and find a remediator that will agree to work with you on this. Remediators are not likely to have heard about it – yet microparticles have been identified as inflammagens and may be significant for your health. A conventional remediation job runs the risk of leaving behind elevated levels of microparticles because neither HEPA vacuuming nor negative air machines remove them. Before final cleaning and while containment is still up, fogging would be done and then a wipe-down done of the containment area.

Introduction to what you need to know about the mold industry, including testing, choosing an inspector, and choosing a remediation firm.

The purpose of this section is to give you a go-to place for working with a conventional mold inspector and mold remediator. You need to know what you might be facing and what to expect. Information here will help you in understanding mold reports, in interviewing mold inspectors and remediators and in negotiating through the various approaches to mold remediation.

Let’s start with some general information on the types of common fungi and then apply that to understanding lab reports.

First, a warning: A very common mold in all these scenarios is the common mold, Aspergillus, which can grow in human tissue (sinuses, lungs, etc.). Wear a P100 or N95 respirator when handling mold (and fiberglass). Wear goggles when working above your head. Have no exposed open sores.

Aspergillus infections are treated with anti-fungals which can damage your liver and kidneys, since your body is made up of the same compounds that mold is made of. The prudent approach is to avoid infection and not be careless around mold.

There is so much we (and the mold industry) do not know about mold and mold remediation. The science is in its infancy and is very complex. Please review Cutting Edge information.

Our goal is to remove mold growth in a home.

In response to the comment that “mold is everywhere,” yes, it is. Mold spores blow in every time you open the front door. For health concerns, however, there should be no mold growth in your home. Out of perhaps 3000 home inspections, I have not found mold growth in maybe a dozen homes. Assume it’s somewhere in your home and find and eliminate it.

Not all mold growth requires the services of a professional remediator. Many times eliminating mold growth is a homeowner’s maintenance job, or can be done by a careful and knowledgeable homeowner.

Just get rid of it (safely and effectively). What level you go to get rid of it depends on your comfort level and the levels of health concerns and sensitivities of family members. The mold industry operates on the level of spores. If there is no visible mold remaining, and spore trap levels are low, they are happy. This happiness may prove to be premature, if sources of mold remain and if clean up has released smaller mold particulates to room air.

Now, let’s review common molds by types:

Alternaria: Dark-colored mold associated with water leaks; linked with asthmatic and other symptoms.

Aspergillus: Green, white; can grow just from elevated relative humidity and condensation; very common in basements and at leaks (wall cavities, ceiling cavities); common in contaminated AC systems; can grow on furniture in damp houses; common in attics with poor ventilation if moisture gets trapped; spores become airborne easily, linked with many health issues; Aspergillus infections can be fatal, especially in immuno-compromised individuals, such as from chemotherapy or organ transplants. Wear a P100 or N95 respirator when working with mold.

Chaetomium: Black mold sometimes seen on the bottoms of ceiling beams in the basement and on the bottoms of rafters in the attic as black splotches. These are often of little consequence, left over from the time of construction, dead mold – but should be wiped off and perhaps sanded (or sprayed with Concrobium Mold Stain Remover) before a house is put on the market. Even dead mold particulates can be allergenic, so wear a P100 or N95 respirator whenever dealing with mold. Chaetomium can also grow around water leaks.

Cladosporium: Black; grows at areas of condensation (window sills, AC vent covers, AC coils and ductwork, window AC units, shower grout and at ceilings; most common outdoor mold; spores don’t become airborne that easily indoors and so the mold can be wiped off; melanin may leave a dark stain; allergenic to some people, plus linked with other health issues.

Penicillium: Green, white; grows at areas of water leakage, condensation, and dampness; one of the most allergenic fungi; can grow in medical equipment; linked with health effects.

Stachybotrys: Black, needs prolonged wetness from water leaks or flooding to grow, likes drywall, spores do not become airborne as easily as Asp-Pen; linked with pulmonary hemorrhages in infants under 8 months and potential neurological damage in all ages. Can give off a mycotoxin used in germ warfare. This is the fungus written up in many news articles and the fungus that “launched” the mold industry.

Trichoderma: Green, sometimes seen in wood grain in the basement around plumbing pipe access holes, where pipes have had condensation. Some individuals very sensitive to Trichoderma; can give off similar mycotoxins to Stachybotrys; is not reported on in spore trap testing.

Ulocladium: another black mold associated with water leaks; linked with health effects.

Where are these fungi commonly (but not only) found in houses?

AC systems – Cladosporium, Asp-Pen

Basements – Asp-Pen, Cladosporium, Trichoderma, Chaetomium
Drywall wall/ceiling cavity leak areas – Asp-Pen, Stachybotrys, Cladosporium (Mold doesn’t like plaster walls.)
Attics – Cladosporium, Ulocladium, Chaetomium

What you need to know about the mold industry, i.e., understanding a lab report?
  • Typically the report has 2 numbers for each fungus, i.e., the raw count and the count per cubic meter. For example, if the inspector samples 1/10th of the air found in a cubic meter and the lab reported one spore, the count per cubic meter would be 10 – even though only spore was found. Many folk (and unscrupulous or less knowledgeable mold professionals) look at the higher number, the mathematical extrapolation, and get spooked. I look at the raw counts.
  • Look at the raw count for Asp/Pen. Spherical spores are lumped together under “Asp/Pen” on the lab report. Asp/Pen are marker molds for dampness, etc. While there are no established standards, I like to see single digits for Asp/Pen. If the raw count is higher, I go looking for the source of mold growth.
  • For the most part, ignore the Cladosporium levels. They are typically from the outside. Sometimes they are from the inside, but in such cases, Asp/Pen should also be elevated.
  • Take a look at Stachybotrys. If I see any spores there, even one, I go looking for the source of growth.
  • For the most part, this is what you need to know from spore trap tests. Oh, and don’t bother with gravity plate-type spore trap testing (a kit from a local home supply store). These are not known for their accuracy. People see the black mold that grows and get spooked – but these colonies are usually only Cladosporium. If there are 10 green colonies on the plate, I would pay attention, but not for the black colonies. If there are no green colonies, remember that these tests are not known for their accuracy and could be giving a false negative. Save your money, in my opinion.

What you need to know about the mold industry, i.e., how spore trap lab reports can be misused:

  • Many inspectors compare indoor counts with outdoor counts and make a pronouncement. Without knowing the species of the mold (not just the genera), such a comparison would not be valid – and you can’t get the species of mold from spore trap testing. For example, if there is a raw count of 40 Aspergillus/Penicillium in outside air and a raw count of 30 in inside air, no conclusions can be drawn regarding indoor contamination. There are 200 species of the genus Aspergillus and 200 species of the genus Penicillium. Without knowing the species, you are comparing apples and oranges. The 30 indoor spores might have blown in from the outside, but they could just as easily be from an indoor source.  In general, comparing indoor and outdoor counts is irrelevant.
  • When the raw count is looked at, the number is much lower than the counts per cubic meter. The raw count is a real number; counts per cubic meter is an extrapolated number. Beware of remediators who try to scare you with the counts per cubic meter (CFU/M3, where CFU stands for “colony forming units,” or spores). For example, one lab report showed a low number (single digits) for the raw count, but the counts per cubic meter was pointed to by the remediator as substantiating the need for expensive remediation – done by them, of course. Such a remediator is either a crook or doesn’t understand how to read lab reports.
  • Some inspectors/remediators look at the total spore count and make a pronouncement based on that. Here’s my tip to you. Forget the total spore count, and look at the Asp/Pen raw count. If you have mold (from dampness or leaks), you’ll almost always have Asp/Pen at a minimum. I like to see low single digits for that raw count. If those counts are low, be cautious about what the remediator is telling you. Also look for the presence of Stachybotrys and Chaetomium spores. These genera are markers for mold contamination from water leaks.

What you need to know about the mold industry, i.e., about hiring a mold inspector.

  • Mold inspectors should be independent of mold remediators. It is a conflict of interest for a company to both ends of the process.
  • Mold inspectors are not trained to work with an on-site microscope and so may not know as much as you know by the time you read through the Where to Sample tab. Thus, the burden may be on YOU to do some pre-testing with tape samples – see How to Test for Mold. You may need to give guidance to the mold inspector. Sad but true.
  • They are trained to do a visual inspection — but now you know that a lot of mold is not visible to the naked eye. They will take swab or tape samples from what appears to be visible mold, and send the sample to a lab.
  • Conventional mold inspectors are trained as extensions of microbiological laboratories. Every sample they take is sent to a laboratory. They are trained to take spore trap air samples, one on each level of the house. Air sampling does not always pick up on a mold issue – and even if it did, you still don’t know where the sources are. If you don’t know where the sources are, how will you know where to do remediation?
  • Lawsuits underlie the mold industry. Everyone has to protect his/her back, or thinks they do. Consequently, not enough samples can be taken to do a really good job at finding mold.
  • Finding mold is not the main issue in a conventional mold inspection… yet it should be absolutely central. As stated above, if you don’t know where the sources of growth are, how will you know where to remediate?
  • Air samples are taken on each level of the house, often excluding the attic.
  • Too many inspectors still compare indoor and outdoor counts. For the most part, this comparison is misleading. If the inspector says, “Outdoor counts are higher than indoor for Asp/Pen, so there’s no problem,” the proper response is, “For what species of Asp/Pen?” If the indoor species are different from the outside species, there’s no comparison. The problem is, you don’t get species identification with spore trap testing, so comparing indoor and outdoor counts is bogus.
  • Mold inspectors are not trained to think in terms of contamination in wall or ceiling cavities (unless there is visible mold on drywall at the site or a moisture meter registers positive for wetness). Yet, Aspergillus and Penicillium can continue growing in wall cavities. As they grow, they give off gases which can penetrate into room air and affect your health. You may have to ask the inspector to drill a hole in a wall or ceiling cavity and take a sample.
  • They are apt to recommend a less-than-satisfactory approach, such as having cleaning done and then re-testing — without one word about searching for the source(s) of mold growth. Save your money.
  • Working with me with tape samples may be more useful to you than hiring a local mold inspector – sad, but true. Or, buy your own microscope and do your own investigation.
  • That said, there are good inspectors out there, too. Look for someone who searches for mold sources, not just acts like a lab technician taking samples on each floor plus the outside.
  • Inspectors should put in their report what their criteria are for a successful remediation job, i.e., what levels of raw counts for Asp-Pen they are looking for in final spore trap testing. One remediator used very low levels of Asp-Pen in their own post-remediation testing to pounce: “Oh, you still have Asp-Pen. We can clean the rest of your house for a mere $4,400.” One wonders how low they were looking for counts to be before considering the room air ok.
What you need to know about the mold industry: interviewing mold remediators.
  • Mold remediators typically follow the protocols drawn up by mold inspectors. Sometimes, if an issue is straightforward, they might not need the mold inspector’s protocol.
  • Mold remediators are trained to wear personal protection equipment, set up containment, and set up negative pressure (or air scrubbers). They are trained to remove and bag contaminated materials, to HEPA-vacuum and sanitize suspect surfaces, and to either spray on a mold retardant product or an encapsulant (which is more permanent than a mold retardant product).
  • Mold remediators typically use products that contain pesticides. Do you really want to get rid of one toxin (mold) and bring in another (chemical pesticides)? Some homeowners and remediation workers have gotten sick from conventional mold treatment products.
  • “Green” mold remediators may use products that are less toxic but may also not stand the test of time. That is, mold may re-grow.
  • Before you sign on the dotted line, you should come to an agreement with the remediator on what products will be used in your home.
    • Borax is a least toxic and effective cleaner for cleaning mold off unfinished wood surfaces, such as sheathing, studs, joists, etc. (1 cup per gallon of water, or sprinkle some powder on a damp sponge; available in the laundry aisle of a supermarket.)
    • Benefect, available on-line, is an EPA-registered sanitizer which can be used for cleaning and in areas of sewage contamination.
    • Caliwel is an EPA-registered biocide (kills mold) and biostat (encapsulant that seals and protects the surface), available from 212-317-0100, www.alistagen.com, and www.homedepot.com. 2 thin coats are recommended. Industrial Caliwel is opaque but has more lime; Architectural Caliwel is more like paint. Because of Caliwel’s high pH, a stainless steel sprayer is essential. An aluminum sprayer would clog up.
    • Other EPA-registered encapsulants likely contain pesticides (also known as mildewcides and biocides). If the label has an EPA registration number, it contains a pesticide. With Caliwel, the pesticide is lime.
    • Concrobium Mold Stain Remover is an acidic foam that removes mold stains from rafters and ceiling joists.
  • A compromise may need to be reached about how to clean surfaces, such as ceiling joists and subflooring. Money is at stake here, because labor costs are involved. National guidelines call for starting with a clean surface. In contrast, the Caliwel manufacturer says that a moderate amount of mold can just be painted over (spray painted). If Caliwel is sprayed and subsequently protects the surface, then sanding off buried hyphae (like “roots”) may be unnecessary, unless for a cosmetic reason, since the Caliwel finish may be opaque. If, however, stains need to be addressed, spray on Concrobium Mold Stain Remover after wiping off visible mold with Borax and before encapsulating with Caliwel. You may want Caliwel sprayed on without cleaning; your remediator may insist on cleaning first in line with industry guidelines. Your decision may decide who you hire.  Tip: The tendency for contractors is to over-spray, using unnecessary product, sometimes twice as much as estimated.
  • Will an encapsulant be used? Not all remediators feel this is necessary, but use of an encapsulant would be my recommendation if any wood remains that may have buried hyphae (“roots”). Protect cleaned surfaces from future growth – either from new spores or from re-growth of buried hyphae. If mold grew once on a surface, especially in a basement, why wouldn’t it grow again? Protect the surface.
What you need to know about the mold industry: scenarios for mold remediation

These are the scenarios that are addressed below:

  • Scenario 1: A plumbing or roof leak (mold in a wall or ceiling cavity or sink cavity)
  • Scenario 2: Mold in a crawlspace
  • Scenario 3: Mold in an almost inaccessible crawlspace
  • Scenario 4: Mold in an unfinished basement
  • Scenario 5: Mold in a finished basement
  • Scenario 6: Mold in an attic
  • Scenario 7: Mold in living areas
  • Scenario 8: Mold in HVAC systems (heating, ventilation, and air conditioning)
  • Scenario 9: Post-remediation testing

Scenario 1: A plumbing or roof leak (mold in a wall or ceiling cavity or sink cavity)

General guidelines

  • Workers must wear personal protection (P100 or N95 respirator, preferably with nostril valve, etc.). If working overhead, wear goggles.
  • Protect the clean areas of the house by setting up containment.
  • As needed, set up an air scrubber or negative air machine.
  • Using plastic sheeting, seal off supply vents and returns in the vicinity of the work space.
  • Remove contaminated drywall and insulation, etc., and place in plastic bags for proper disposal.
  • HEPA-vacuum in the cavity.
  • Using a strong flashlight, examine for signs of further water penetration or discoloration.
  • Make sure there has been sufficient demolition – better too much than too little. Examine nearby surfaces, including drywall, flooring, ceiling material, etc. Trace the path of water to find the mold.
  • If needed, send me tape samples (fee) from peripheral areas to confirm that sufficient removal of contaminated drywall, etc., has been done. It’s better to remove too much drywall than too little.
  • If materials that will remain (studs, sill plate, ceiling joists, and sheathing) have signs of mold growth, HEPA-vacuum the growth and then wipe off with a little Borax sprinkled on a damp sponge or cloth.
  • Finish cleaning, and arrange for post-remediation testing as needed.
  • Apply two coats of encapsulant to wood surfaces that may have had mold growth or need to be protected.
  • Routine cleaning with a quality HEPA-vacuum cleaner and damp-dusting (or dusting with a microfiber cloth) will continue to reduce levels of stray spores and other mold particulates.

Scenario 2: Mold in a crawlspace

General guidelines

  • If there was insulation put between ceiling joists at the time of construction, the insulation may have protected the wood surfaces it covered from mold. Highest levels of mold are likely to be on the edges of the ceiling joists that are exposed to the air.
  • Concrete typically does not support the growth of mold. However, if moisture migration through the foundation wall has resulted in efflorescence (a deposit of minerals and dirt on the foundation wall), there may be some mold mixed in that efflorescence. Cleaning off efflorescence is a homeowner’s periodic maintenance job. HEPA-vacuum, and take steps to reduce moisture intrusion.
  • Workers must wear personal protection (P100 or N95 respirator, preferably with nostril valve, etc.) for both mold and fiberglass.
  • If the entry to the crawlspace is through the house or basement, take steps to contain the crawlspace work area and to minimize the risk of cross-contamination.
  • Remove insulation and bag for proper disposal.
  • Examine the subflooring for signs of water penetration and discoloration. If present, HEPA-vacuum and wipe off with Borax sprinkled on a sponge or cloth.
  • Apply two coats of encapsulant to subflooring and ceiling joists.
  • Arrange for post-remediation testing if desired. Raw count levels of spores in crawlspaces may not be as low as in other areas because of cleaning limitations.

Commentary on crawlspaces:

The more modern way of thinking about a crawlspace is to make it part of the house. That is, essentially set up plastic sheeting (like a swimming pool liner) to separate the crawlspace from the earth outside. Insulation is put on walls. Then a fan or dehumidifier would be placed in the crawlspace and it would be open to the interior, assuming there is an opening. Vents to the exterior are sealed off. Some crawlspaces are too shallow and too hard to get around in for any “swimming pool liner” to work.

The more old-fashioned (and maybe more practical) way of thinking about a crawlspace is to protect it from mold growth and to have adequate ventilation (vents can be shut in the winter). This approach costs a lot less, because you don’t need to run a dehumidifier. When wood is protected by an encapsulant, mold spores can come and go. Who cares, as long as they have nothing to feed on. Setting up a fan near a corner to ricochet air around the crawlspace may be a good idea, to keep air moving. After encapsulation, insulation may be placed between ceiling joists.

Scenario 3: Mold in an almost inaccessible crawlspace

  • Sometimes the best you can do is to exhaust the smelly air. Figure out how to promote cross-ventilation. In the central states and New England, prevailing winds are from the northwest, so have a vent open at the northwest and place an exhaust fan in a window or vent in the southeast, to draw air through.
  • Check out The Wave ventilation for crawlspaces on-line. I have no experience with this unit, except for some positive feedback from a few clients.

Scenario 4: Mold in an unfinished basement

General guidelines

  • Rule out the presence of other toxic materials, such as lead and asbestos. If present, they should be dealt with first.
  • Protect the living areas of the house from cross-contamination. If there is an outside entrance to the basement, use that exclusively and seal off the door to the upstairs.
  • Set up air scrubber(s) and negative pressure.
  • Seal off vents or returns. If applicable, make sure sufficient oxygen is present for heating units.
  • Clean contents and move them to a clean area for storage.
    • How to clean contents:
      • Glass, metal, and plastic items can be washed or wiped off.
      • Soft items such as wicker, paper, cloth, and upholstered furniture may need to be placed in plastic bags or wrapped in plastic sheeting and discarded.
      • Furniture to be retained can have its unfinished surfaces HEPA-vacuumed and wiped down with Borax. If furniture is really moldy, it may not be salvageable. Sometimes wood surfaces are steamed by remediators.
      • Mold can grow more easily on soft wood such as pine than on hard wood such as oak. Mold grows more easily on unfinished surfaces than finished surfaces.
      • Change items stored in cardboard boxes to plastic boxes or plastic bags and bag and discard the boxes.
      • If there are antique or costly items you especially value and do not wish to discard, confer with your remediator or call a fine arts restorer or museum restoration department.
      • Some furniture can be preserved by cleaning and then encapsulating every square inch of unstained wood, including inner framing.
      • If you have no other place to store cleaned items, they may need to be stored in the basement. If so, set up a temporary plastic room (containment area) and remediate that room first. Then move cleaned items to that area. Cleaned items may also be covered with drop cloths.
      • Smaller items can be cleaned and transferred to plastic boxes for storage.
  • When the basement is cleared out, remove any insulation and place in plastic bags for proper disposal.
  • HEPA-vacuum as needed to prepare surfaces for encapsulation.
  • Apply two coats of encapsulant to every square inch of wood in the basement, including ceiling joists, subflooring, steps, backing of electric box, workbenches, and shelves. Apply encapsulant to surfaces not visible when standing in the basement, such as the surfaces of support wood that face upwards and the underside of steps.
  • Complete the cleaning process. One standard of care in the industry is the “black glove test.” A black glove wiped on a surface should come up clean. Of course, in a basement, that is next to impossible – but it does indicate how thorough the cleaning process should be. Mold particulates settle into dust, so dust must be removed.
  • Arrange for post-remediation testing, to consist of spore trap testing (with raw count results preferably in single digits) and a visual check.
  • If desired, apply a moisture retardant such as www.decoproducts.com or Thoroseal to foundation walls. Of course, take needed steps to reduce moisture intrusion into the basement.

Scenario 5: Mold in a finished basement 

This scenario will involve some demolition of building materials, or gutting of the basement.

General guidelines

  • After contents are moved, remove carpeting and wrap for proper disposal.
  • Make a judgment call on how much of the finished walls and ceiling need to be removed. If the basement is damp, consider removing all. If the basement has been dry and there was a recent flood, maybe you can get away with removing the bottom 4’ of drywall and any insulation. If you caught the water quickly, maybe you could remove the bottom 2” of paneling and cover the gap with composite base molding later, after drying and encapsulating inside the opening.
  • Send me tape samples from remaining materials as needed to rule out additional growth.
  • Finish demolition as needed.
  • HEPA-vacuum in wall cavities.
  • Apply two coats of encapsulant to wood surfaces, not to concrete.
  • Finish cleaning.
  • Arrange for post-remediation testing as needed.

Scenario #6: Mold in an attic

  • Attic mold typically has one of these patterns:
    • A dark sheen on sheathing due to condensation and lack of ventilation – this is typically Cladosporium but may be other fungi, too.
    • Green or white fuzz on rafters and sheathing, particularly where the rafters meet the sheathing – this is typically Aspergillus or Penicillium, due to trapped moisture and lack of ventilation.
    • Areas of black splotches on rafters – this is typically old Chaetomium, usually dead, left over from the time of construction – black stain may remain due to melanin in the mold.
    • Green or black mold that is heavy in the attic may call for professional remediation. Dark areas of mold may be sanded off or sprayed with Concrobium Mold Stain Remover. Dark mold on sheathing may be painted with a paint-like encapsulant. Explore options with your remediator. Sometimes replacement of sheathing is the best option.
    • Make sure bathroom exhaust fans extend through the roof to the exterior and are not dumping moisture in the attic.
    • Check the attic ventilation for adequate air exchange.
    • If you don’t have adequate insulation, including over the attic access, and if leak holes haven’t been sealed up from the 2nd floor, your heating bill is higher than it should be. Review the Energy tab.

Scenario 7: Elevated levels of mold in living areas

  • If no sources of mold growth have been found in living areas, then treat this as a dust-removal project. In-depth spring and fall cleanings are good practices to follow.
  • Make sure you have a quality HEPA vacuum cleaner.
  • Damp-dust or use a microfiber cloth.
  • If desired, get a room air purifier, such as the IQAir. Or, upgrade the furnace/AC filter to a good quality pleated filter – like the 2 3/4″ model.
  • Keep the premises ship-shape, with a minimum of dust collectors.
  • If possible, avoid carpeting which, from a health perspective, is one of the worst investments in a home.

Scenario 8: Mold in HVAC systems

  • If your system has had a fiberglass filter, there is a good chance the system could use a cleaning. The preferred filter is a pleated media filter.
  • Electrostatic and electronic cleaners are not recommended, both because they can lose efficiency as dust coats surfaces and with electronic cleaners, levels of AC electric fields are elevated throughout the house when the electronic cleaner runs, as demonstrated by an electrical engineer colleague with a frequency analyzer.
  • From a health perspective, the purpose of the filter is to protect the AC coils from dust and dirt. The coils are the site of condensation. If they are clean, there is no problem. If they are dirty, mold could grow.
  • Before contracting with a service, read the EPA brochure on duct cleaning. Go to www.epa.gov/iaq and search on “duct cleaning.” Another good place to check out is www.nadca.com, the website of the North America Duct Cleaners Association, and then click on the Residential tab.
  • Some duct cleaning companies do just that, clean ductwork. Avoid them. You need a company that will clean the whole system, especially AC coils.
  • If the AC coils cannot be cleaned in place, they should be removed for cleaning. If they are old, just replace them.
  • Flexduct (plastic tubular ductwork) cannot be adequately cleaned and should be replaced. The one exception is when the flexduct is not particularly dirty and then perhaps it can be air-puffed out. Discuss with the remediator or duct cleaner.
  • Avoid biocides. Just ask for mechanical cleaning, including vacuuming, puffing, and mechanical agitation. Regarding biocides, you may prove to be sensitive to these chemicals. Further, who knows, after the active ingredient is gone, whether the residual compounds may serve as food for mold, bacteria or viruses.

Scenario 9: Post-remediation testing

Post-remediation testing is typically done, both to protect you and to protect the remediator. If the job fails the test, many remediators will re-clean until it passes. The remediator may also use the post-remediation testing results against you if a future complaint is registered. “We don’t know what you did in the interim, but there was no mold when we finished the job. Look at the lab results. Sure, we’ll come back and clean more, but we have to charge you.” They may be more diplomatic than that – or maybe not.

Here are types of post-remediation testing:

  • The most common type of testing is a visual examination plus spore trap sampling, where air samples are taken in the work area, a control area, and outside. These samples must be submitted to a microbiology laboratory for analysis. There are no standards for what is acceptable, but I look for single digits in the raw count for Aspergillus/Penicillium, except for attic and crawlspace results which may be higher.
  • If a paper trail is not needed for legal purposes, I generally do culture plate testing, which can be studied in-house (and sent to a lab afterwards if needed). Depending on whether surfaces have been encapsulated yet or not, I may also do tape-testing. Once a surface has been encapsulated, it is not possible to tell how much mold was painted over. With Caliwel, that may not matter so much.
  • There are no “right” answers for exactly when to do post-remediation testing or for what levels of mold are within satisfactory limits. These things are debated in the industry and left up to individual inspectors.
  • I have long felt that a lot of post-remediation testing is little more than a test of how good the air scrubbers or negative air machines are. If the machine has just been turned off, or may still be on, the air is going to be artificially clean. Test a month later, and see what it’s like — only few inspectors or remediators would think that testing a month later was a good idea. Since we already know the limitations of the mold industry, the burden is even more on you to supervise this process and to know where the mold is and what you want done before you get involved with either mold inspectors or mold remediators. A word to the wise….

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